Long durability high performance steel for structural, machine and tooling applications

Abstract

To provide hot work steels having high toughness.SOLUTION: The invention relates to steels, in particular hot work steels having high toughness, even if taking high thickness thereof into account, including steels having long durability combined with mechanical, tribological and thermodynamic properties for applications requiring sophisticated technology, and steels which can achieve high environmental resistance and resistance to highly destructive media combined with other properties. These steels may also be manufactured at low cost. The invention also describes a method for processing steels having high thickness and methods for processing materials through multiple steps, including additive manufacturing to manufacture at least a part of an intermediate mold, a mold or a model, Cold Isostatic Pressing (CIP), elimination of the mold, densification, and other steps.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to steel, particularly steel that has high toughness even in large cross sections.

[0002] Additionally, the present invention relates to a long-lasting steel with the physical, tribological, and thermodynamic properties required for high-tech applications. The steel invention can be formulated to have high environmental resistance and resistance to aggressive media with a combination of other related properties. The invention also allows the steel to be produced inexpensively. [Background technology]

[0003] Hot work tooling materials have been known for a long time and we have classified them as AISI H. Those with the more favorable combination of mechanical properties associated with aluminum die casting are H11 and H13, which are often used.

[0004] Over the past few years, efforts have been made to improve the hardenability of these materials. In particular, attempts have been made to increase the alloying percentages of Mo and Cr. Also, the addition of small amounts of other elements such as N has been tried. These attempts have resulted in an increase in the cross-section that maintains stable strength at the processing temperature, but the effect on toughness has in all cases been negligible.

[0005] Also, attempts were made to reduce the %S and %P content to improve toughness. This was expanded to %Sn, %Sb, %Pb, %As, etc. Ultimately, these attempts led to an improvement in thermal conductivity by reducing the alloying content. In particular, trace elements (e.g., %Cu, %Ni, etc.) did not contribute to the fundamental mechanical properties. These attempts resulted in a by-product of improved crack resistance and some improvement in conductivity. However, in no case was it possible to obtain parameters related to toughness at high layer thicknesses.

[0006] Since Harry Brearley's development of stainless steels and his numerous patents, there have been numerous publications and scientific attempts to combine one property with another, usually a mechanical property, to achieve high application potential.

[0007] The strong effect of %P on ferrite strength, as well as its detrimental effects on forming performance and ductility, has long been known. For strength enhancement, and where ductility is not an issue, %P can be increased to 0.2%. Its pronounced effect on bake hardenability has been exploited industrially by increasing its content to 0.1%. Phosphorus is also known to significantly reduce core losses in motor laminates, and is exploited by increasing its content to 0.155%. It has also been widely published that the ductility of %P is significantly reduced by the presence of Mn, Si, Ti, Nb, V, Mo, Cr, and other carbide formers (see Figure 1 for %Ti). Due to concerns that the P content limits the purity of the steel at the expense of toughness, keeping the P content low is often desirable. However, when cost is a concern, ferroalloys with a P content as low as 0.1% may still be used, even though they have a high P content. Some inventors increase the P content for two reasons: one is to investigate improving the alloy's lubrication by forming phosphorus compounds; the other is to promote eutectic steadite and / or sulfides, or to induce liquid-phase sintering by lowering the liquidus temperature. In both cases, the alloy may also require wear resistance. To achieve this, carbide-forming elements, particularly Cr, Mo, W, and V, are added. In special cases, Zr, Ta, Ti, and Hf are sometimes used. In all cases, the carbide-forming elements form carbides or other hard molecules (especially nitrides, borides, or compounds), but they do not freely oxidize and passivate the surface, as in the present invention. Furthermore, the alloys may contain %Ni, %Mn, %Si, %Cu, or in the special case %Al, for various purposes, but primarily for hardenability, or in the case of %Al, for precipitation hardening. There are also papers investigating improved scale resistance. Comments are made on the most relevant records that deserve the inventor's attention.

[0008] US 1,707,364 is a record of a report of improved scale resistance in alloys (%C<1.5%; %P: 0.05-50%, %Cr: 3-30%; %Mo and %Si can also be included in the alloy). This alloy can contain %P well above its solubility limit in iron, meaning that the level of toughness is not suitable for the present invention. Furthermore, while this alloy promises improved resistance to scale formation, it lacks corrosion resistance due to the lack of a strong, insoluble, thin oxide former. Thus, it is completely incompatible with the results required by the present invention. If %Cr is considered the only protective oxide former, this report also fails to clarify that special considerations are required to utilize %Cr for oxidation at low levels of this element, as indicated by the present invention. A %P of 50% is almost impossible to achieve using the methods described in the present invention, and examples indicate that the maximum practical level is 0.157%. As usual, when %C is 0.4% and %Cr is 2-3%, there are no strong carbide formers, i.e., almost all of the %Cr is bound to carbides and not free to form a protective oxide layer.

[0009] US 4,909,843 is a wear-resistant alloy containing %P to obtain lubricant effects, all characterized by a high %C content and the absence of strong oxide builders: US 5,545,247, US 5,631,431, US 6,852,143 B2; DE 3,712,107; DE 3,712,108 A1; US ​​2,038,639; US 2,186,758; US 2,256,135; US 3,698,877; US 3,977,838; US 4,000,980; US 4,702,771; US ​​4,778,522; and US 4,836,848, all of which contain %Cr.

[0010] US3767386 describes a cast iron for brake shoe manufacture (%C: 2.7-3.5%; %Si: 1.0-2.0%; %Mn: 0.4-1.5%; %P: 1.0-3.0; s<0.15% and Ti: 0.3-0.7%), with %V, %Cr and %Mo containing up to 1.25%. Again, the lubricant effect is pursued, and Ti at a low content tightly binds carbides to control the grain size and provides additional wear resistance. In addition, the %C content is much higher than that of the present invention.

[0011] US 4,243,414 describes liquid phase sintered alloys in which the melting point is reduced by adding either %P, %B or %Si. The %C content is so high that the required strong, insoluble thin oxide is not present, let alone the characteristics of the active element. A similar case is US 4,790,875, where %Ti may be present. In this case, %C is mainly outside the scope of the present invention, and both %P and %Ti are bound. Therefore, the desired effect of the present invention cannot be expected. %Ti is bound to carbides and therefore cannot be oxidized, and %P is bound to steadite Fe-CP.

[0012] US 4,043,808 describes the use of %P additions to control the fragmentation behavior of steels: the %P content is too low and the appropriate oxide formers are not present at all in the correct form.

[0013] Within the scope of stainless steel inventions, replacements containing little or no chromium have been sought. One of the most notable advances in this regard is the so-called Fe-Mn-Al alloys. With manganese contents ranging from 15 to 40% and aluminum contents ranging from 5 to 15%, these alloys have been reported to exhibit good resistance to aggressive environments such as NACE solution (5% wt NaCl, 0.5% wt acetic acid, balance distilled water with HS bubbles), but perform less well in acidic chloride-bearing media. The metallurgical concept is quite different from that of the present invention. Large amounts of manganese are used to austenitize the alloy and limit the %Fe content, and large amounts of aluminum are also used to obtain a protective aluminum oxide layer. There is no need to stabilize the iron oxide. Much higher alloying, particularly in the %Al, is required in the present invention. Also, no improved mixed oxides have been used. This %Al content poses problems in terms of mechanical properties and alloy cost.

[0014] Another group of alloys worth considering are the so-called high-Mn TRIP and TWIP steels. Developed later than the previously mentioned Fe-Mn-Al corrosion-resistant steels, these steels are characterized by a high Mn content, which allows for high mechanical strength and elongation. While mechanical properties must be taken into account, corrosion resistance is not an issue, so the Al content is kept low, only increasing the stacking fault energy of austenite and suppressing the formation of ε / martensite. The aluminum in these alloys often forms precipitates with the iron. Numerous patents and publications exist on these alloys, such as JPH0483852(A) or EP0889144(A1). The use of P as a reinforcement in this group of alloys is particularly useful for improving castability (in terms of melt fluidity), as in WO2013124283A1, where P is newly used to improve the cold workability of TRIP and TWIP steels. Although the same authors made significant efforts to simultaneously achieve corrosion resistance and the TRIP / TWIP effect, as in DE 10 2010 026 808 A1 (where %Cr is used to make the alloy environmentally resistant), the environmental resistance of this alloy is not reported. The main reason is that %Al was not provided as a protective oxide former and %P was not provided as an iron oxide stabilizer. Thus, other steps and alloying rules required to ensure the alloying elements are present in the desired form were not observed as reported in this invention.

[0015] If the elements must be active and their presence is not worthless, then protective oxide formers, particularly those present in the form of carbides, borides, or nitrides, are of no use, and %P present in the form of steadies and phosphates is of little value. For this reason, it is very important to the practice of this invention that special care be taken to ensure that the critical elements are present in the correct form. It is essential to verify the presence of the elements in the correct form, not just add them. [Brief explanation of the drawings]

[0016] [Figure 1]Plot of d(dL / L) / dt (length-normalized length increment divided by time increment) versus temperature during cooling and detection for conventional H11 below 600°C. The curve is fairly flat and shows a sudden drop at temperature TD. [Figure 2] Plot of d(dL / L) / dt (normalized increase in length divided by the increment in time) versus temperature during cooling for 3356LAB-3 of the present invention below 600°C. The curve is fairly flat and shows a sudden drop at temperature TD. Number 1 in the circle in Figure 2 refers to the curve plot, and number 2 in the circle in Figure 2 refers to an example value of TD. [Figure 3] Taffel plot of the compositions in Table 3. [Figure 4] Examples of embossing plates. 1 - Inside the AM intermediate mold. 2 - Outside the intermediate mold. 3 - Elastic preform. 4 - Particulate matter. 5 - Pressure during CIP. DETAILED DESCRIPTION OF THE INVENTION

[0017] Commonly used hot work materials for applications with high mechanical demands are hot work tool steels. They are usually alloys of chromium, molybdenum, or tungsten. Often, these materials also contain other alloying elements such as vanadium, silicon, manganese, niobium, or aluminum. These materials exhibit a very good combination of creep strength and toughness at working temperatures.

[0018] The process for manufacturing tools using this type of material, or tools containing this type of material, involves softening mechanical treatment, heat treatment, and finishing and conditioning machining steps. Some material properties are highly sensitive to quenching. For these reasons, particular attention is paid to the homologation process during heat treatment. For this type of material, it is generally recognized that the time spent moving from 800 to 500 during the quenching process is very important, especially when considering properties related to toughness. Whether a structure different from martensite forms during the quenching process is also important.

[0019] The problem is that the cooling medium is limited to ensure fast enough quenching, and in most cases, these tools or dies have complex geometries, so rapid cooling would result in cracking or extreme distortion. Therefore, due to the limited maximum cooling rate, the critical rate of cooling can only be achieved if the cross section of the material being quenched is sufficiently small. This makes heat treatment of hot-worked materials for mechanically demanding applications (such as most light alloy pouring, casting, superelastic deformation of sheet, extrusion, copper / bronze / brass pouring, etc.) impossible in dies and large, thick tools.

[0020] In this paper, if a strip is defined by the orthogonal measures of its three sides in a Cartesian coordinate system, its thickness is the smallest measure of the three sides.

[0021] In this document, all percentages are by weight.

[0022] In this document, when the mass of an element is expressed below, 0% means that it is specifically included, or equivalently, that it is absent. When the mass of an element is given in a range starting from 0, this includes unintentional inclusion. It also includes the element being completely absent from the composition.

[0023] In this document, fracture toughness is measured according to the ASTM E399 standard.

[0024] A first aspect of the invention relates to a steel with high layer thickness but high toughness.

[0025] As mentioned above, it is possible to achieve high quench hardenability in hot worked materials, but achieving high toughness values ​​when quenched with high layer thicknesses is another matter. The inventors have found that this is possible with the correct alloying and heat treatment. This is possible with the following composition ranges:

[0026]

number

[0027] For the purposes of this document, unless otherwise specified, a trace element refers to any element present in an amount less than 2%. Depending on the application, a trace element may be present in an amount less than 1.4%, more preferably less than 0.9%, and ideally less than 0.78%. The following elements, whether elemental or compound, may be considered trace elements: H, Li, Na, K, Rb, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ac, Tc, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Au, Zn, Cd, Hg, B, Ga, In, Tl, Ge, Sn, Pb, P, As, Sb, Bi, O, S, Se, Te, Po, F, Cl, Br, I, At, He, Ne, Ar, Kr, Xe, Rn, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr. In some applications, trace elements, or trace elements in general, can be critical for certain relevant properties (e.g., thermal conductivity or toughness). In such applications, trace elements below 0.4% are appropriate. Alternatively, trace elements below 0.2%, or even 0.14%, are desirable, and ideally below 0.06%. Needless to say, being below a certain amount also includes the absence of an element. In many cases, it is obvious or desirable to have most or all of the trace elements absent. As mentioned above, all trace elements are considered to be a single substance. Therefore, very often, different trace elements have different maximum weight percentage allowances. Trace elements may be intentionally added to achieve specific functions, including cost reduction. Alternatively, their presence (if any) may be unintentional and primarily related to alloying element impurities and waste from alloy production. The reasons for the presence of different trace elements may vary for the same alloy production process.

[0028] The inventors have discovered that for some applications it is desirable for the total trace element content to be 2.0% or less, for other applications it is 1.4% or less, for other applications it is 0.8% or less, for other applications it is 0.2% or less, and for still other applications it is 0.1% or less or 0.06% or less.

[0029] The inventors have also discovered that it is desirable for the content of individual trace elements to be less than 2.0% in some applications, less than 1.4% in others, less than 0.8% in others, less than 0.2% in others, and less than 0.1% or even less than 0.06% in still other applications.

[0030] The inventors have found that in certain applications, it is required that trace elements such as Ca, P, and S are not present in the composition. In certain applications, it is required that Ca is not present as a trace element in the composition of the steel. In certain applications, it is also required that P is not present as a trace element in the composition of the steel. In other specific applications, it is also required that S is not present as a trace element in the composition of the steel.

[0031] The present inventors have found that Ti, Ta, Zr, Hf, Nb, La, Ce, and Cs are optional elements in the composition of the steel, and that in some embodiments, any or all of them may be absent from the composition.

[0032] The inventors have also found that in some applications, it is desirable for %Ti+%Ta+%Zr+%Hf+%Nb+%La+%Ce+%Cs=0-4.2%.

[0033] The inventors have also found that in some applications, it is desirable for %Ti+%Ta+%Zr+%Hf+%Nb+%La+%Ce+%Cs=0-3.7%.

[0034] The inventors have also found that in some applications, it is desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce+%Cs=0-2.2%.

[0035] The present inventors have also found that in some applications, it is desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce+%Cs=0.001-2.2%.

[0036] Carbon equivalent is very important in determining most of the relevant properties. When high mechanical resistance at high temperatures is required, %Ceq should not be too low. In some applications of this development, the inventors have found that %Ceq greater than 0.36% is desirable. In some applications of this development, the inventors have found that %Ceq greater than 0.38% is desirable. In some applications of this development, the inventors have found that %Ceq greater than 0.41% is desirable. When high toughness or high elongation, or both, are required, %Ceq should not be too high. In some applications of this development, the inventors have found that %Ceq less than 0.58% is desirable. In some applications of this development, the inventors have found that %Ceq less than 0.48% is desirable. In some applications of this development, the inventors have found that %Ceq less than 0.44% is desirable.

[0037] The inventors have found that in some applications it is desirable for the %Ceq to be between 0.32% and 0.54%, usually between 0.34% and 0.51%, or even between 0.35% and 0.48%.

[0038] For carbon equivalent materials, %C is very important. When high mechanical resistance at high temperatures is required, %C cannot be too low. In some applications of this development, it has been found desirable for %C to be greater than 0.36%. In some applications of this development, it has been found desirable for %C to be greater than 0.38%. In some applications of this development, it has been found desirable for %C to be greater than 0.41%. Also, when high toughness and / or high elongation are required, %C cannot be too high. In some applications of this invention, it has been found desirable for %C to be less than 0.58%. In some applications of this invention, it has been found desirable for %C to be less than 0.48%. In some applications of this invention, it has been found desirable for %C to be less than 0.44%.

[0039] It has been found that for some applications, %C is desired to be between 0.32% and 0.54%, usually between 0.34% and 0.51%, or even between 0.35% and 0.48%.

[0040] For carbon equivalent materials, it is sometimes desirable that the %N content not be too high. In some applications of the present invention, %N less than 0.09% is desirable, in others. In some applications of the present invention, the inventors have found that %N less than 0.004% is desirable, and in others, no %N is desirable. In some applications, %N has been found to improve hardenability. In some applications, %N greater than 0.06% is desirable, and in other applications, %N greater than 0.11% is desirable.

[0041] It is also desirable that the %B content of the carbon equivalent material is not too high. In some applications of the present invention, %B is less than 0.03%. In some applications of the present invention, %B is less than 0.019%. In some applications of the present invention, %B is less than 0.009%. In other applications, it has been found that the absence of %B is desirable. It has been found that %B improves hardenability, particularly by inhibiting ferrite transformation. In this case, it is desirable that %B be greater than 0.002%. In this case, it is desirable that %B be greater than 0.0042%. In this case, it is desirable that %B be greater than 0.006%.

[0042] The presence of chromium in secondary carbides almost always plays a major role, and chromium content is therefore crucial in determining most of the relevant properties. It has been discovered that %Cr greater than 3.6% is desirable when high-temperature mechanical resistance is required without excessively compromising toughness. In some applications of this development, it has been found desirable for %Cr to be greater than 4.2%. In some applications of this development, it has been found desirable for %Cr to be greater than 4.6%. Also, when high toughness and / or high elongation are required, it may be desirable for %Cr not to be too high. This is particularly important when the content of carbide formers, such as %V, %Mo, and %W, is high. In some applications of this invention, it has been found desirable for %Cr to be less than 5.8%. In some applications of this invention, it has been found desirable for %Cr to be less than 5.4%. In some applications of this invention, it has been found desirable for %Cr to be less than 4.9%.

[0043] It has been found that in some applications it is desirable for %Cr to be between 2.9% and 5.9%, and in many cases between 3.6% and 5.9%, or even between 4.1% and 5.9%.

[0044] It has been found that in some applications, it is desirable for %Cr-%Mn (which indicates the difference between %Cr and %Mn: %Cr-%Mn) to be greater than 1.2%, in certain applications it is normally greater than 1.6%, and in other applications it is greater than 1.9%.

[0045] It has also been found that in some applications it is desirable for %Cr+%Mn to be greater than 2.8%, and in certain applications it is usually greater than 3.4%, in other cases greater than 4.1%, and in certain other applications greater than 4.9%.

[0046] It has been found that in certain applications where %C is greater than 0.4%, %Cr is desired to be greater than 3.6%, in other applications greater than 3.9%, and in other cases greater than 4.1%.

[0047] The manganese content is very important in the present invention. It has been found that at a certain %Mn content, the material of the present invention has high toughness, even when machining thick layers. This is not a gradual effect, but if the %Mn is too low, this property is not observed. At a certain %Mn content, this property becomes observed. This critical content depends on the specific amounts of other elements in the alloy. For certain applications of the present invention, it has been found desirable to have %Mn greater than 0.8%. For certain applications of the present invention, it has been found desirable to have %Mn greater than 1.1%. For certain applications of the present invention, it has been found desirable to have %Mn greater than 1.6%. For certain applications of the present invention, it has been found desirable to have %Mn greater than 2.1%. For certain applications of the present invention, it has been found desirable to have %Mn greater than 2.6%. For certain applications of the present invention, it has been found desirable to have %Mn greater than 3.1%. Depending on the content of other elements in the alloy, a too high %Mn content has been found to adversely affect the ease of machining of the steel. In certain applications of the present invention, it has been found desirable for %Mn to be less than 4.8%. In certain applications of the present invention, it has been found desirable for %Mn to be less than 4.4%. In certain applications of the present invention, it has been found desirable for %Mn to be less than 3.9%. In other applications, it has been discovered that it is desirable for %Mn to be absent from the alloy composition.

[0048] For some applications of the present invention, %Mn is desired to be between 0.1% and 5.8%, typically between 2.1% and 4.9%, and for other applications, 2.2% and 4.9%. For still other applications, %Mn is desired to be between 2.3% and 4.9%, or even between 3.1% and 4.6%.

[0049] When %C is 0.38%, the inventors have discovered that in some applications of the present invention it is desirable for %Mn to be greater than 1.1%, and in other applications it is desirable for %Mn to be greater than 1.6%, or even greater than 2.1%.

[0050] It has also been found that when %C is less than 0.55%, it is desirable for %Mn to be greater than 1.6% for some applications of the present invention, typically greater than 2.1% for other applications, or greater than 2.2% for certain applications.

[0051] It has also been found that when %C is between 0.45% and 0.55% and %Cr is between 4.4% and 4.6%, it is desirable for some applications of the present invention for %Mn to be greater than 0.3%, for other applications typically greater than 1.1%, or for certain applications greater than 2.1%.

[0052] It has also been found that when %C is greater than 0.45% and %Cr is less than 3.9%, for some applications of the present invention it is desirable for %Mn to be greater than 0.5%, for other applications typically greater than 1.3%, or for certain applications greater than 2.1%.

[0053] It has also been found that when %C is less than 0.45%, it is desirable for %Mn to be greater than 0.6% for some applications of the present invention, typically greater than 0.8% for other applications, or greater than 2.1% for certain applications.

[0054] It has also been found that when %C is less than 0.45% and %Cr is less than 3.6%, for some applications of the present invention it is desirable for %Mn to be greater than 0.7%, for other applications typically greater than 1.3%, or for certain applications greater than 2.1%.

[0055] It has also been found that when %C is less than 0.65%, it is desirable for %Mn to be greater than 1.1% for some applications of the present invention, typically greater than 1.3% for other applications, or greater than 2.1% for certain applications.

[0056] It has also been found that when %C is greater than 0.45% and %Cr is greater than 2.8%, for some applications of the present invention it is desirable for %Mn to be greater than 0.8%, for other applications typically greater than 1.3%, or for certain applications greater than 2.1%.

[0057] It has been found that %Mn can be partially substituted for %B or %Ni, or both, in certain effects. In certain applications of the present invention, the inventors have discovered that it is desirable for %Mn and %Ni to be present simultaneously in the amounts described herein. In other applications, it has been found that it is desirable for %Mn, %B, and %Ni to be present simultaneously in the amounts described herein. In fact, it has been found that the presence of %Mn is essential when there is not a sufficient content of either %B or %Ni (values ​​described herein).

[0058] The nickel content plays a very important role, especially in its effect on hardenability. Nickel also plays an important role as a substitute for %Mn, which exhibits the unique effects reported in this paper. In some applications of the present invention, it has been found desirable for %Ni to be greater than 0.25%. In some applications of the present invention, it has been found desirable for %Ni to be greater than 0.32%. In some applications of the present invention, it has been found desirable for %Ni to be greater than 0.52%. When toughness is required, especially at high temperatures, it may be necessary for %Ni not to be too high. In some applications of the present invention, it has been found desirable for %Ni to be less than 1.8%. In some applications of the present invention, it has been found desirable for %Ni to be less than 0.78%. In some applications of the present invention, it has been found desirable for %Ni to be less than 0.49%.

[0059] In some applications of the present invention, it has been found that it is desirable that %Ni is not present in the composition. It has also been found by the inventors that when %Ni and %B are not present in the composition, it is desirable that %Mn>0.1%. In other applications where %Ni and %B are not present in the composition, it has been found that it is desirable that %Mn>1.6%, and in other applications under the same conditions, it is desirable that %Mn>2.6%.

[0060] It has been found that in some applications it is desirable for %Ni to be between 0% and 2.8%, and often between 0% and 2.4%, or even between 0.1% and 2.6%.

[0061] In some applications where %C may be less than 0.36% and %Cr less than 3.6%, it has been found desirable for %Ni to be less than 2.4%, and in many cases less than 2.3%, or in certain applications less than 2.2%.

[0062] In some compositions, the %Si can counteract the beneficial effects of the present invention and adversely affect toughness values ​​when working with thick layers. In some applications of the present invention, %Si is less than 0.4%. In some applications of the present invention, %Si is less than 0.18%. In some applications of the present invention, %Si is less than 0.08%. In some applications of the present invention, %Si is less than 0.04%. In other cases, the present inventors have found that the absence of %Si is desirable.

[0063] It has been found that in some applications it is desirable for %Si to be between 0% and 1.2%, and in many cases between 0% and 1.2% or even between 0% and 0.4%.

[0064] It has been found that in some applications where %C is less than 0.55%, %Si is desirable to be less than 0.95%, and in other applications under similar conditions it is usually desirable to be less than 0.8%, or even less than 0.6%.

[0065] It has been found that in some applications where %C is less than 0.55% and %Cr is less than 4.6%, %Si is desirable to be less than 1.4%, and in other applications under similar conditions it is usually desirable to be less than 0.95%, or even less than 0.7%.

[0066] It has been found that in some applications where %C is less than 0.36% and %Cr is less than 3.1%, %Si is desirable to be greater than 0.6%, and in other applications under similar conditions it is usually desirable to have %Si greater than 0.7% or even 0.8%.

[0067] It has been found that in certain applications where %C is less than 0.4% and %Cr is between 4.9% and 5.4%, %Si is desirable to be greater than 0.25%, and in other applications under similar conditions it is usually desirable to have greater than 0.3% or even 0.35%.

[0068] It has been found that in some applications where %C is less than 0.4% and %Cr is between 4.9% and 5.5%, %Si less than 1% is desirable, and in other applications under similar conditions it is usually desirable to have less than 0.9% or even less than 0.75%.

[0069] It has been found that in some applications where %C is less than 0.48% and %Cr is between 4% and 5.7%, %Si should be less than 0.75%, and in other similar applications it is usually desirable to have less than 0.65% or even less than 0.55%.

[0070] Also, in some applications it is desirable for %Si + %Mn + %V to be greater than 0.1%. It has been determined by the inventors that in some applications it is desirable for %Si + %Mn + %V to be greater than 0.26%, or in other cases it is desirable for %Si + %Mn + %V to be greater than 0.4%.

[0071] It has been found that in some compositions, certain values ​​of %Se + %Te + %As + %Pb + %Sb + %Sn can be advantageous for machining. In some applications of the present invention, it has been found that it is even more desirable for the alloy composition to contain %Se + %Te + %As + %Pb + %Sb + %Sn greater than 0.052%. However, certain values ​​of %Se + %Te + %As + %Pb + %Sb + %Sn can have a detrimental effect on the steel of the present invention. In particular, high %Mn contents can interfere with the desired effects of a high %Mn content. In some applications of the present invention, it has been found that %Se + %Te + %As + %Pb + %Sb + %Sn is less than 0.19%. In other cases, it has been found that it is desirable for %Se + %Te + %As + %Pb + %Sb + %Sn to be less than 0.09%. In some applications of the present invention, it is desirable for %Se + %Te + %As + %Pb + %Sb + %Sn to be less than 0.04%. It has been found that some applications of the present invention require %Se+%Te+%As+%Pb+%Sb+%Sn to be less than 0.008%, and other applications require %Se+%Te+%As+%Pb+%Sb+%Sn to be 0%.

[0072] It has been found that in some compositions, certain values ​​of %As + %Sb + %Sn can be advantageous for machining. In some applications of the present invention, it has been found that a %As + %Sb + %Sn content of greater than 0.052% is even more desirable in the alloy composition. However, certain values ​​of %As + %Sb + %Sn can have a detrimental effect on the steel of the present invention. In particular, high %Mn contents can interfere with the desired effect of a high %Mn content. In some applications of the present invention, it has been found that %As + %Sb + %Sn is desired to be less than 0.19%, in other cases less than 0.09%, in other cases less than 0.04%, and in other cases less than 0.008%. In some applications, it has been found that their absence is desired.

[0073] It has been found that in some compositions, certain values ​​of %Se + %Te can be advantageous for machining. In some applications of the present invention, it has been found that %Se + %Te greater than 0.052% is desirable in the alloy composition. However, certain values ​​of %Se + %Te can have a detrimental effect on the steel of the present invention. In particular, high %Mn contents can interfere with the desired effects of a high %Mn content. In some applications of the present invention, it has been found that %Se + %Te less than 0.19% is desirable. In some applications of the present invention, it has been found that %Se + %Te less than 0.09% is desirable. In some applications of the present invention, it has been found that %Se + %Te less than 0.04% is desirable. In some applications of the present invention, it has been found that %Se + %Te less than 0.008% is desirable. In some applications, their absence is desired.

[0074] It has been found that in some applications of the present invention, %P + %S is more present in the alloy composition. In some compositions, the value of %P + %S may have a detrimental effect on the steel of the present invention. In particular, a high %Mn content may interfere with the desired effect of a high %Mn content. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.028%. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.018%. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.008%. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.0004%. It has been found that in other applications, the compositional content of %P + %S is required to be 0%.

[0075] It has been found that in some applications of the present invention, P is more present in the alloy composition. In some compositions, the %P value may have a detrimental effect on the steel of the present invention. In particular, when the %Mn content is high, the expected effect of a high %Mn content may be impaired. It has been found that in some applications of the present invention, %P is desired to be less than 0.028%. It has been found that in some applications of the present invention, %P is desired to be less than 0.018%. It has been found that in some applications of the present invention, %P is desired to be less than 0.008%. It has been found that in some applications of the present invention, %P is desired to be less than 0.0008%. It has been found that in other applications, %P is desired to be 0%.

[0076] It has been found that in some applications of the present invention, S is more present in the alloy composition. In some compositions, the %S value may have a detrimental effect on the steel of the present invention. In particular, when the %Mn content is high, the expected effect of a high %Mn content may be impaired. It has been found that in some applications of the present invention, %S is desired to be less than 0.018%. It has been found that in some applications of the present invention, %S is desired to be less than 0.008%. It has been found that in some applications of the present invention, %S is desired to be less than 0.0008%. It has been found that in some applications of the present invention, %S is desired to be less than 0.0004%. It has also been found that in other applications, %S is required to be 0%.

[0077] It has been found that in some applications of the present invention, O is more present in the alloy composition. In some compositions, the %O content may have a detrimental effect on the steel of the present invention. In particular, when the %Mn content is high, the expected effect of a high %Mn content may be impaired. It has been found that in some applications of the present invention, %O is desired to be less than 14 ppm. It has been found that in some applications of the present invention, %O is desired to be less than 9 ppm. It has been found that in some applications of the present invention, %O is desired to be less than 6 ppm. It has been found that in some applications of the present invention, %O is desired to be less than 4 ppm. It has also been found that in other applications, the absence of %O is desired in the composition.

[0078] In some applications of the present invention, it has been found that %H2 is more prevalent in the alloy composition. In some compositions, %H2 can have a negative impact on toughness. In some applications of the present invention, it has been found that %H2 less than 1.8 ppm is desired. In some applications of the present invention, it has been found that %H2 less than 0.9 ppm is desired. In some applications of the present invention, it has been found that %H2 less than 0.4 ppm is desired. In some applications of the present invention, it has been found that %H2 less than 0.08 ppm is desired. In other applications, it has been found that the absence of %H2 in the composition is desired.

[0079] The molybdenum content is almost always significant in determining most relevant properties, as it plays a major role in secondary carbides. When tempering resistance is desired, the molybdenum content should not be too low. In some applications of the present invention, it has been found desirable for %Mo to be greater than 0.6%. In some applications of the present invention, it has been found desirable for %Mo to be greater than 1.1%. In some applications of the present invention, it has been found desirable for %Mo to be greater than 1.6%. Also, when high toughness and / or high elongation are desired, the %Mo should not be too high. This is true even when the content of carbide formers such as %V, %Cr, or %W is high. In some applications of the present invention, it is desirable for %Mo to be less than 2.8%. In some applications of the present invention, it is desirable for %Mo to be less than 1.9%. In some applications of the present invention, it is desirable for %Mo to be less than 1.4%. In some applications of the present invention, it is desirable for %Mo to be less than 0.8%. In other applications, it has been found desirable for %Mo to be absent.

[0080] It has been found that in some applications it is desirable for %Mo to be between 0.01% and 4.1%, and in many cases between 0.5% and 3.9%, or even between 0.8% and 2.8%.

[0081] It has also been found that when %C is less than 0.45% and %Cr is between 4.9% and 5.5%, for some applications of the present invention it is desirable for %Mo to be greater than 1.6%, for other applications typically greater than 1.7%, or for certain applications greater than 1.8%.

[0082] It has also been found that when %C is 0.45% to 0.55% and %Cr is 4.4% to 4.6%, for some applications of the present invention it is desirable for %Mo to be less than 2.9%, for other applications typically less than 2.8%, or for certain applications less than 2.6%.

[0083] It has also been found that when %C is less than 0.44% and %Cr is less than 3.3%, for some applications of the present invention it is desirable for %Mo to be greater than 0.6%, for other applications typically greater than 0.7%, or for certain applications greater than 0.8%.

[0084] It has also been found that when %C is less than 0.55% and %Cr is less than 3.3%, for some applications of the present invention it is desirable for %Mo to be greater than 0.6%, for other applications typically greater than 1.6%, or for certain applications greater than 1.8%.

[0085] For the application of the present invention, it has been found that %Mo can be partially substituted with an amount twice the weight of %W. Also, in some applications, the above %Mo can be substituted with %W, but in that case, the amount must be twice the original %Mo value. In this sense, %Moeq is worthy of consideration as a partial substitute. When used as a substitute, the required amount to be added is expressed as %Moeq = %Mo + 1 / 2 %W. The required value of %Moeq corresponds to the description of %Mo above.

[0086] It has been found that in some applications, %W is desired to be between 0.01% and 6.1%, and in many cases between 0.5% and 4.1%, or even between 0.8% and 3.6%.

[0087] It has been found that in some applications, a %Moeq of 0.1% to 3.9%, often 0.18% to 3.9%, or even 0.8% to 2.8% is desirable.

[0088] The vanadium content is almost always significant in determining most of the relevant properties, as it plays a major role in secondary carbides. When tempering resistance is desired, %V should not be too low. In some applications of this invention, it has been found desirable for %V to be greater than 0.22%. In some applications of this invention, it has been found desirable for %V to be greater than 0.32%. In some applications of this invention, it has been found desirable for %V to be greater than 0.55%. In some applications of this invention, it has been found desirable for %V to be greater than 0.85%. Also, when high toughness and / or high elongation are desired, %V should not be too high. This is true even when the content of carbide formers such as %Mo, %Cr, or %W is high. In some applications of this invention, it is desirable for %V to be less than 1.8%. In some applications of this invention, it is desirable for %V to be less than 1.2%. In some applications of this invention, it is desirable for %V to be less than 0.8%. It has been found that in some applications of the present invention, a %V of less than 0.4% is desired, while in other applications, no %V is desired.

[0089] It has been found that in some applications, %V is desired to be between 0% and 2.4%, and in many cases between 0% and 1.3%, or even between 0.3% and 0.9%.

[0090] It has been found that in certain applications where %C is greater than 0.4%, a %V greater than 0.35% is desirable.

[0091] It has been found that in certain applications where %C is greater than 0.38%, it is desirable for %V to be less than 0.45%, typically less than 0.4%, and in other cases less than 0.35%.

[0092] It has been found that in certain applications where %C is less than 0.4% and %Cr is 4.9% to 5.4%, it is desirable for %V to be less than 0.9%, typically less than 0.8%, and in other cases less than 0.7%.

[0093] It has been found that in certain applications where %C is less than 0.4%, it is desirable for %V to be less than 0.8%, typically less than 0.7%, and in other cases less than 0.65%.

[0094] It has also been found that when %C is less than 0.55% and %Cr is less than 4.6%, it is desirable for %V to be less than 0.45% for some applications of the present invention, and typically less than 0.4% for other applications.

[0095] It has also been found that when %C is less than 0.65% and %Cr is greater than 5.6%, for some applications of the present invention it is desirable for %V to be less than 0.55%, for other applications it is typically less than 0.5%, and in other cases it is less than 0.45%. It has been found that in certain applications where %C is greater than 0.4%, it is desirable for %V+%Mo to be greater than 1.6%, typically greater than 1.7%, and in other cases greater than 1.8%.

[0096] It has been found that in certain applications where %C is greater than 0.38%, it is desirable for %V+%Nb to be less than 0.45%, and in other cases less than 0.4%. It has also been found that when %C is less than 0.48% and %Cr is between 4% and 5.7%, it is desirable for %V to be less than 0.75% for some applications of the present invention, and typically less than 0.65% for other applications.

[0097] It has been found that in some applications it is desirable for %V+%Mo+%W>0.01%, and in many cases %V+%Mo+%W>0.1%, or even %V+%Mo+%W>1.6%.

[0098] In some cases, it is desired that the %Ti content is not excessive. In some applications of the present invention, it is desired that %Ti is less than 1.8%. In some applications of the present invention, it is desired that %Ti is less than 1.3%. In other cases, it is desired that %Ti is absent. In other cases, %Ti helps improve the properties of the steel. In such cases, it has been found that %Ti is desired to be more than 0.001%. In such cases, it has been found that %Ti is desired to be more than 0.1%.

[0099] It has been found that in some applications it is desirable for the %Ti to be between 0% and 1.6%, typically between 0% and 0.9%, and in other cases between 0.3% and 0.1%.

[0100] In some cases it is desired that the %Co content is not excessive. In some applications of the present invention it is desired that %Co is less than 2.3%. In some applications of the present invention it is desired that %Co is less than 1.2%. In other cases some applications require that %Co is absent. In other cases %Co helps improve the properties of the steel. In such cases it has been found that %Co is desired to be more than 0.001%. In such cases it has been found that %Co is desired to be more than 0.1%.

[0101] It has been found that in some applications it is desirable for %Co to be between 0% and 2.1%, typically between 0% and 1.7%, and in other cases between 0.01% and 1.3%.

[0102] In some cases it is desired that the %Cu content is not excessive. In some applications of the present invention it is desired that %Cu is less than 1.1%. In some applications of the present invention it is desired that %Cu is less than 0.4%. In other cases some applications may require that %Cu is absent. In other cases %Cu may help improve the properties of the steel. In such cases it has been found that %Cu is desired to be more than 0.001%. In such cases it has been found that %Cu is desired to be more than 0.1%.

[0103] It has been found that in some applications it is desirable for the %Cu to be between 0% and 0.9%, typically between 0% and 0.7%, and in other cases between 0.01% and 0.6%.

[0104] It has been found that in some applications where %C is less than 0.46% and %Cr is between 4.65% and 5.6%, it is desirable for %Cu to be less than 0.28%, typically less than 0.2%, and in other cases less than 0.1%.

[0105] In some cases it is desired that the %Al content is not excessive. In some applications of the present invention it is desired that %Al is less than 0.35%. In some applications of the present invention it is desired that %Al is less than 0.2%. In other cases it is desired that %Al is absent. In other cases %Al helps to improve the properties of the steel. In such cases it has been found that %Al is more than 0.001% is desired. In such cases it has been found that %Al is more than 0.1% is desired.

[0106] It has been found that in some applications it is desirable for the %Al to be between 0% and 0.35%, typically between 0% and 0.25%, and in other cases between 0.01% and 0.25%.

[0107] It has been found that in some applications it is desirable for %Cu+%Co+%Al+%Ti>0.01%, typically %Cu+%Co+%Al+%Ti>0.1%, and in other cases %Cu+%Co+%Al+%Ti>0.2%.

[0108] It has been found that in some applications it is desirable for %Cu+%Co+%Al+%Ti to be between 0.01% and 4%, usually between 0.1% and 3%, and in other cases between 0.2% and 3%.

[0109] It has been found that in some applications it is desirable for %V+%Al+%Ti>0.001%, typically %V+%Al+%Ti>0.01, and in other cases %V+%Al+%Ti>0.1.

[0110] It has been found that in some applications it is desirable for %V+%Al+%Ti to be between 0.001% and 4%, typically between 0.01% and 3%, and in other cases between 0.1% and 3%.

[0111] The inventors have discovered that for some compositions, the sum of %Gd + %Nd + %Sm + %Y + %Pr + %Sc + %Pm + %Eu + %Tb + %Dy + %Ho + %Er + %Tm + %Yb + %Lu can be beneficial to the structure of certain inclusions. It has been found that in some applications of the present invention, a sum of %Gd + %Nd + %Sm + %Y + %Pr + %Sc + %Pm + %Eu + %Tb + %Dy + %Ho + %Er + %Tm + %Yb + %Lu greater than 0.2% is required. However, depending on the sum of %Gd + %Nd + %Sm + %Y + %Pr + %Sc + %Pm + %Eu + %Tb + %Dy + %Ho + %Er + %Tm + %Yb + %Lu, toughness may be adversely affected. In some applications, it has been found desirable for %Gd+%Nd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb+%Lu to be less than 0.04%. In some applications, it has been found desirable for %Gd+%Nd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb+%Lu to be less than 0.008%. In other applications, it has been found desirable for the sum of %Gd+%Nd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb+%Lu to be 0%.

[0112] In some applications of the present invention, it has been found that %Al, %Ti, %Ta, %Zr, %Hf, %Nb, %Cu, %Co, %La, %Ce, and %Cs have a detrimental effect on toughness. In such cases, %Al, %Ti, %Ta, %Zr, %Hf, %Nb, %Cu, %Co, %La, %Ce, and %Cs should be less than 0.38%. In other applications, it is desirable for %Al, %Ti, %Ta, %Zr, %Hf, %Nb, %Cu, %Co, %La, %Ce, and %Cs to be less than 0.18%. In other applications, it is desirable for %Al, %Ti, %Ta, %Zr, %Hf, %Nb, %Cu, %Co, %La, %Ce, and %Cs to be less than 0.08%. In still other applications of the present invention, it is desirable for all %Al, %Ti, %Ta, %Zr, %Hf, %Nb, %Cu, %Co, %La, %Ce, and %Cs to be absent.

[0113] It has been found that in some applications, processing is restricted to %Zr+%Hf+%Ta+%Nb>0.001%, or in many cases %Zr+%Hf+%Ta+%Nb>0.01%, or %Zr+%Hf+%Ta+%Nb>0.1%.

[0114] In some applications, we have found that %Zr+%Hf+%Ta+%Nb can be reduced to 0.001% to 4%, or in many cases to 0.01% to 3%, or even 0.1% to 3%.

[0115] A 350 mm thick steel having the above composition is heat treated using a method including the following steps: austenitizing at a temperature above 1020°C, after which the steel is subjected to a minimum of three tempering steps, at least one of which must be above 520°C, resulting in a fracture toughness at room temperature of above 51 MPa√m and a hardness of 42-44 HRc.

[0116] In this aspect of the invention, the inventors have demonstrated that a simple dilatometry experiment can select compositions useful in a range of applications involving large cross sections. A dilatometer with repeatability and accuracy better than 0.005%, the ability to resolve increment lengths of 5 nm or greater, and the ability to achieve constant cooling with temperature deviations not exceeding 5°C is desirable. This experiment involves austenitizing a candidate material at 1030°C for at least 20 minutes and cooling to 100°C at a constant cooling rate of 3 K / min. The plot shows d(dL / L) / dt (normalized increment length divided by increment time) versus temperature during cooling. Also, the curve below 600°C is very flat, with a sudden drop at temperature TD (see Figures 1-2: 1-curve plot and 2-TD value sample). In one embodiment, TD is 0.5*10 -4 min -1 is the temperature at which a drop in -4 min -1 In another embodiment, TD is the temperature at which a drop in -4 min-1 In another embodiment, the temperature at which the -4 min -1 The temperature at which a decrease in TD occurs. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is 360°C or less. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is 340°C or less. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is 318°C or less. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is 290°C or less. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is 2740°C or less. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is 260°C or less. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is 230°C or less.

[0117] Any of the above applications may be combined in any combination with any other implementation described herein, with different steel compositions, so long as the properties are compatible.

[0118] Another aspect of the present invention is high toughness and high thermal conductivity at high layer thicknesses.

[0119] As mentioned above, it is possible to achieve high quench hardenability in hot-worked materials, but achieving high toughness values ​​when hardened with high layer thicknesses is another matter. It seems impossible to achieve properties other than high thermal conductivity. The inventors have found that this is possible with the correct alloying and thermomechanical processing. This is possible with the following composition ranges:

[0120]

number

[0121] For the purposes of this document, unless otherwise specified, a trace element refers to any element present in an amount less than 2%. Depending on the application, a trace element may be present in an amount less than 1.4%, more preferably less than 0.9%, and ideally less than 0.78%. The following elements, whether elemental or compound, may be considered trace elements: H, Li, Na, K, Rb, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ac, Tc, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Au, Zn, Cd, Hg, B, Ga, In, Tl, Ge, Sn, Pb, P, As, Sb, Bi, O, S, Se, Te, Po, F, Cl, Br, I, At, He, Ne, Ar, Kr, Xe, Rn, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr. In some applications, trace elements, or trace elements in general, can be critical for certain relevant properties (e.g., thermal conductivity or toughness). In such applications, trace elements below 0.4% are appropriate. Alternatively, trace elements below 0.2%, or even 0.14%, are desirable, and ideally below 0.06%. Needless to say, being below a certain amount also includes the absence of an element. In many cases, it is obvious or desirable to have most or all of the trace elements absent. As mentioned above, all trace elements are considered to be a single substance. Therefore, very often, different trace elements have different maximum weight percentage allowances. Trace elements may be intentionally added to achieve specific functions, including cost reduction. Alternatively, their presence (if any) may be unintentional and primarily related to alloying element impurities and waste from alloy production. The reasons for the presence of different trace elements may vary for the same alloy production process.

[0122] The inventors have discovered that for some applications it is desirable for the total trace element content to be 2.0% or less, for other applications it is 1.4% or less, for other applications it is 0.8% or less, for other applications it is 0.2% or less, and for still other applications it is 0.1% or less or 0.06% or less.

[0123] The inventors have also discovered that it is desirable for the content of individual trace elements to be less than 2.0% in some applications, less than 1.4% in others, less than 0.2% in others, less than 0.8% in others, and less than 0.1% or even less than 0.06% in still other applications.

[0124] The inventors have found that in certain applications, it is required that trace elements such as Ca, P, and S are not present in the composition. In certain applications, it is required that Ca is not present as a trace element in the composition of the steel. In certain applications, it is also required that P is not present as a trace element in the composition of the steel. In other specific applications, it is also required that S is not present as a trace element in the composition of the steel.

[0125] The present inventors have found that Ti, Ta, Zr, Hf, Nb, La, Ce, and Cs are optional elements in the composition of the steel, and that in some embodiments, any or all of them may be absent from the composition.

[0126] The inventors have also found that in some applications, it is desirable for %Ti+%Ta+%Zr+%Hf+%Nb+%La+%Ce+%Cs=0-4.2%.

[0127] The inventors have also found that in some applications, it is desirable for %Ti+%Ta+%Zr+%Hf+%Nb+%La+%Ce+%Cs=0-3.7%.

[0128] The inventors have also found that in some applications, it is desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce+%Cs=0-2.2%.

[0129] It has been found that in some applications it is desirable for %Ti+%Ta+%Zr+%Hf+%Nb+%La+%Ce+%Cs to be greater than 0.001%, in many cases greater than 0.01%, and in other applications greater than 0.1%.

[0130] It has also been found that in some applications it is desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce+%Cs=0.001-2.2%.

[0131] Carbon equivalent is very important in determining most of the relevant properties. When high mechanical resistance at high temperatures is required, %Ceq should not be too low. In some applications of this development, the inventors have found that %Ceq greater than 0.26% is desirable. In some applications of this development, the inventors have found that %Ceq greater than 0.31% is desirable. In some applications of this development, the inventors have found that %Ceq greater than 0.41% is desirable. When high toughness or high elongation, or both, are required, %Ceq should not be too high. In some applications of this development, the inventors have found that %Ceq less than 1.4% is desirable. In some applications of this development, the inventors have found that %Ceq less than 0.8% is desirable. In some applications of this development, the inventors have found that %Ceq less than 0.44% is desirable. In some applications of this development, the inventors have found that %Ceq less than 0.39% is desirable. In some applications of this development, the inventors have found that it is desirable for the %Ceq to be less than 0.34%.

[0132] It has been found that in some applications a %Ceq of 0.31% to 0.59%, in many applications 0.28% to 0.59%, and in other applications 0.31% to 0.39% is desirable.

[0133] For carbon equivalent materials, %C is very important. When high mechanical resistance at high temperatures is required, %C should not be too low. In some applications of this invention, it has been found desirable for %C to be greater than 0.26%. In some applications of this invention, it has been found desirable for %C to be greater than 0.31%. In some applications of this invention, it has been found desirable for %C to be greater than 0.41%. Also, when high toughness and / or high elongation are required, %C should not be too high. In some applications of this invention, it has been found desirable for %C to be less than 1.4%. In some other applications of this invention, it has been found desirable for %C to be less than 0.8%. In some applications of this invention, it has been found desirable for %Ceq to be less than 0.44%. In some applications of this invention, it has been found desirable for %Ceq to be less than 0.39%. In some applications of this invention, it has been found desirable for %Ceq to be less than 0.34%.

[0134] It has been found that in some applications a %C of 0.31% to 0.59%, in many applications 0.28% to 0.59%, and in other applications 0.31% to 0.39% is desirable.

[0135] For carbon equivalent materials, it may be desirable that the %N content is not too high. In some applications of the present invention, %N less than 0.09% is desirable. In some applications of the present invention, the inventors have found that %N less than 0.004% and in other cases no %N is desirable. In some applications, %N has been found to improve hardenability. In some applications, %N greater than 0.06% has been found to be desirable. In some applications, %N greater than 0.11% has been found to be desirable.

[0136] It is also desirable that the %B content of the carbon equivalent material is not too high. In some applications of the present invention, %B is less than 0.03%. In some applications of the present invention, %B is less than 0.019%. In some applications of the present invention, it has been found that %B is less than 0.009%, and in other applications, %B is absent. It has been found that %B improves hardenability, particularly by inhibiting ferrite transformation. In this case, it is desirable that %B be greater than 0.002%. In this case, it is desirable that %B be greater than 0.0042%. In this case, it is desirable that %B be greater than 0.006%.

[0137] The chromium content is very important in determining most of the relevant properties. If corrosion resistance is required, the %Cr should not be too low. In some applications, it has been found that %Cr greater than 0.6% is desirable. In some applications, it has been found that %Cr greater than 1.2% is desirable. In some applications, it has been found that %Cr greater than 2.1% is desirable. Also, if high toughness, high elongation, tempering resistance, and / or high thermal conductivity are desired, it may be desirable not to have too high a %Cr. This is especially important when the content of carbide formers such as %V, %Mo, and %W is high. In some applications, it has been found that %Cr less than 1.9% is desirable. In some applications, it has been found that %Cr less than 0.9% is desirable. In some applications, it has been found that %Cr less than 0.78% is desirable. In some applications, it has been found that %Cr less than 0.4% is desirable. In some applications, it has been found that %Cr less than 0.09% is desirable. Also, in other applications it has been found desirable to have no %Cr present in the composition.

[0138] It has been found that in some applications %Cr is desirable to be between 0% and 1.9%, in many cases 0% to 0.9%, and in other applications 0.01% to 0.4%.

[0139] In this section of the invention, the manganese content is essential. It has been found that at certain %Mn contents, the materials of the invention have high toughness, even when machining thick layers. This is not a gradual effect; if the %Mn is too low, this property is not observed. At certain %Mn contents, this property becomes observed. This critical content depends on the specific amounts of other elements in the alloy. For certain applications of the invention, %Mn is greater than 1.4%. For certain applications of the invention, %Mn is greater than 1.8%. For certain applications of the invention, %Mn is greater than 2.1%. For certain applications of the invention, %Mn is greater than 2.6%. For certain applications of the invention, %Mn greater than 3.1% and for other applications, greater than 3.6% has been found to be desirable. Depending on the content of other elements in the alloy, too high a %Mn content has been found to adversely affect the ease of machining of the steel. For certain applications of the invention, it has been found desirable to have %Mn less than 4.8%. For certain applications of the invention, it has been found desirable to have %Mn less than 4.4%. It has been found that in certain applications of the present invention, it is desirable for %Mn to be less than 3.9%.

[0140] It has been found that in some applications a %Mn of at least 1.7% is desired, in other applications a %Mn of 2.2% to 4.9% is desired, and in many applications a %Mn of 2.9% to 4.1%, or even 3.1% to 3.9% is desired.

[0141] It has been found that %Mn can be partially substituted for %B or %Ni, or both, in certain effects. In certain applications of the present invention, the inventors have discovered that it is desirable for %Mn and %Ni to be present simultaneously in the amounts described herein. In other applications, it has been found that it is desirable for %Mn, %B, and %Ni to be present simultaneously in the amounts described herein. In fact, it has been found that the presence of %Mn is essential when there is not a sufficient content of either %B or %Ni (values ​​described herein).

[0142] The nickel content plays a very important role, especially in its effect on hardenability. Nickel also plays an important role as a substitute for %Mn, which exhibits the unique effects reported in this paper. In some applications of the present invention, it has been found desirable for %Ni to be greater than 0.25%. In some applications of the present invention, it has been found desirable for %Ni to be greater than 0.32%. In some applications of the present invention, it has been found desirable for %Ni to be greater than 0.52%. When toughness is required, especially at high temperatures, it may be desirable for %Ni not to be too high. In some applications of the present invention, it has been found desirable for %Ni to be less than 1.8%. In some applications of the present invention, it has been found desirable for %Ni to be less than 0.78%. In some applications of the present invention, it has been found desirable for %Ni to be less than 0.49%. In other cases, the present inventors have determined that the absence of %Ni in the composition is desirable.

[0143] It has been found that in some applications of the present invention, it is desirable that %Ni is not present in the composition. For some applications of the present invention where %Ni and %B are not present in the composition, it is desirable that %Mn>0.1. It has also been found by the inventors that for other applications of the present invention under similar conditions regarding %Ni and %B, it is desirable that %Mn>1.6 or %Mn>2.6.

[0144] It has been found that in some applications %Ni is desired to be between 0% and 2.8%, and in many other applications %Ni is desired to be between 0% and 2.6%, or even between 0.1% and 2.6%.

[0145] In some cases where %Cr + %B + %Ni is too low, %Mo may not be present. It has been found that for some applications of the present invention, when %Cr + %B + %Ni < 0.7, it is desirable that %Mn > 2.2. For other applications of the present invention, when %Cr + %B + %Ni < 0.6, it is desirable that %Mn > 2.3. For other applications, it has been found by the inventors that when %Cr + %B + %Ni < 0.7, it is desirable that %Mn > 2.1.

[0146] In some compositions, %Si can counteract the beneficial effects of the present invention and adversely affect toughness values ​​when working with thick layers. In some applications of the present invention, %Si is less than 0.4%. In some applications of the present invention, %Si is less than 0.18%. In some applications of the present invention, %Si is less than 0.08%. In some applications of the present invention, it has been determined by the inventors that %Si is less than 0.04% and in other cases, no %Si is desired.

[0147] Some applications require a low %Si content, and it has been found that for these applications, %Si is desired to be between 0% and 0.39%, and in many cases between 0.001% and 0.23%, or even between 0.001% and 0.1%.

[0148] It has been found that in some compositions, certain values ​​of %Se + %Te + %As + %Pb + %Sb + %Sn may be advantageous for machining. For some applications of the present invention, it has been found that alloy compositions containing %Se + %Te + %As + %Pb + %Sb + %Sn greater than 0.052% are even more desirable. However, certain values ​​of %Se + %Te + %As + %Pb + %Sb + %Sn may have a detrimental effect on the steel of the present invention. In particular, high %Mn contents may interfere with the desired effects of a high %Mn content. For some applications of the present invention, it has been found that it is desirable for %Se + %Te + %As + %Pb + %Sb + %Sn to be less than 0.19%. For some applications of the present invention, it has been found that it is desirable for %Se + %Te + %As + %Pb + %Sb + %Sn to be less than 0.09%. It has been found that in some applications of the present invention it is desirable for %Se+%Te+%As+%Pb+%Sb+%Sn to be less than 0.04%, in some applications it is desirable for %Se+%Te+%As+%Pb+%Sb+%Sn to be less than 0.008%, and in other applications it is found that it is desirable for %Se+%Te+%As+%Pb+%Sb+%Sn to be 0%.

[0149] It has been found that in some compositions, certain values ​​of %As + %Sb + %Sn may be advantageous for machining. In some applications of the present invention, it has been found that it is even more desirable for the alloy composition to contain %As + %Sb + %Sn greater than 0.052%. However, certain values ​​of %As + %Sb + %Sn may have a detrimental effect on the steel of the present invention. In particular, high %Mn contents may interfere with the desired effects of a high %Mn content. In some applications of the present invention, it has been found that it is desirable for %As + %Sb + %Sn to be less than 0.19%. In some applications of the present invention, it has been found that it is desirable for %As + %Sb + %Sn to be less than 0.09%. In some applications of the present invention, it has been found that it is desirable for %As + %Sb + %Sn to be less than 0.04%. In some applications of the present invention, it has been found that it is desirable for %As + %Sb + %Sn to be less than 0.008%. It is also known that in other applications, %As+%Sb+%Sn is required to be 0%.

[0150] It has been found that in some compositions, certain values ​​of %Se + %Te can be advantageous for machining. In some applications of the present invention, it has been found that alloy compositions containing %Se + %Te greater than 0.052% are even more desirable. However, certain values ​​of %Se + %Te can have a detrimental effect on the steel of the present invention, particularly at high %Mn contents, which can interfere with the desired effects of a high %Mn content. It has been found that in some applications of the present invention, it is desirable for %Se + %Te to be less than 0.19%. It has also been found that in some applications of the present invention, it is desirable for %Se + %Te to be less than 0.09%. It has also been found that in some applications of the present invention, it is desirable for %Se + %Te to be less than 0.04%. It has also been found that in some applications of the present invention, it is desirable for %Se + %Te to be less than 0.008%. It has also been found that in other applications, it is desirable for %Se + %Te to be 0%.

[0151] It has been found that in some applications of the present invention, %P + %S is more present in the alloy composition. Depending on the value of %P + %S in a certain composition, it may have a detrimental effect on the steel of the present invention. In particular, when the %Mn content is high, it may interfere with the expected effect of a high %Mn content. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.028%. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.018%. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.008%. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.0004%. It has been found that in other applications, %P + %S is required to be 0%.

[0152] It has been found that in some applications of the present invention, P is more prevalent in the alloy composition. Some values ​​of %P may have a detrimental effect on the steel of the present invention. In particular, high %Mn contents may interfere with the desired effect of a high %Mn content. It has been found that in some applications of the present invention, %P less than 0.028% is desired. It has been found that in some applications of the present invention, %P less than 0.018% is desired. It has been found that in some applications of the present invention, %P less than 0.008% is desired. It has been found that in some applications of the present invention, %P less than 0.0008% is desired. It has been found that in other applications, %P is required to be 0%.

[0153] It has been found that in some applications of the present invention, S is more prevalent in the alloy composition. Depending on the value of %S, this may have a detrimental effect on the steel of the present invention. In particular, when the %Mn content is high, it may interfere with the expected effect of a high %Mn content. It has been found that in some applications of the present invention, %S is desired to be less than 0.018%. It has been found that in some applications of the present invention, %S is desired to be less than 0.008%. It has been found that in some applications of the present invention, %S is desired to be less than 0.0008%. It has been found that in some applications of the present invention, %S is desired to be less than 0.0004%. It has been found that in other applications, %S is required to be 0%.

[0154] It has been found that in some applications of the present invention, O is more prevalent in the alloy composition. The %O content of a given composition can adversely affect the toughness of the present invention. It has been found that in some applications of the present invention, %O less than 14 ppm is desired. In some applications of the present invention, %O less than 9 ppm is desired. In some applications of the present invention, %O less than 6 ppm is desired. In some applications of the present invention, %O less than 4 ppm is desired. In other applications, %O less than 0% is desired.

[0155] It has been found that in some applications of the present invention, more H2 is present in the alloy composition. The %H2 value of a certain composition can adversely affect the toughness of the present invention. It has been found that in some applications of the present invention, %H2 less than 1.8 ppm is desired. In some applications of the present invention, %H2 less than 0.9 ppm is desired. In some applications of the present invention, %H2 less than 0.4 ppm is desired. In some applications of the present invention, %H2 less than 0.08 ppm is desired. In other applications, %O is found to be 0%.

[0156] The molybdenum content is almost always significant in determining most of the relevant properties, as it plays a major role in secondary carbides. When tempering resistance is required, the molybdenum content should not be too low. In some applications of the present invention, it has been found desirable for %Mo to be greater than 1.6%. In some applications of the present invention, it has been found desirable for %Mo to be greater than 2.1%. In some applications of the present invention, it has been found desirable for %Mo to be greater than 3.1%. When wear resistance is required, even higher %Mo is desirable. In some applications of the present invention, it has been found desirable for %Mo to be greater than 3.6%. In some applications of the present invention, it has been found desirable for %Mo to be greater than 4.1%. In some applications of the present invention, it has been found desirable for %Mo to be greater than 4.6%. Also, when high toughness and / or high elongation are required, the %Mo should not be too high. This is true even when the content of carbide formers such as %V, %Cr, or %W is high. In some applications of the present invention, it has been found desirable for %Mo to be less than 5.4%. It has been found that in some applications of the present invention, %Mo is desired to be less than 4.8%. In some applications of the present invention, %Mo is desired to be less than 4.4%. In some applications of the present invention, %Mo is desired to be less than 3.9%. In some applications of the present invention, %Mo is desired to be less than 2.9%.

[0157] It has been found that in some applications %Mo is desired to be at least 1.4%, in other applications %Mo is desired to be between 1.6% and 5.3%, and in many applications %Mn is desired to be between 2.2% and 4.8%, or even %Mo is desired to be between 3.1% and 3.9%.

[0158] For the applications of the present invention, it has been found that %Mo can be partially replaced by an amount twice the weight of %W. Also, in some applications, the %Mo can be replaced by %W, but in that case, the amount must be twice the original %Mo value. In this sense, %Moeq is worthy of consideration as a partial substitute. The required amount of addition when used as a substitute is expressed as %Moeq = %Mo + 1 / 2 %W. The required value of %Moeq corresponds to the description of %Mo above. However, there are cases where the replacement of %Mo with %W is not desired. For some applications of the present invention, it is desirable for %W to be less than 0.8%. In other applications, it is desirable for %W to be absent.

[0159] It has been found that in some applications, %W is desired to be between 0% and 4.1%, and in many other applications, %W is desired to be between 0% and 2.9%, or even between 0.001% and 2.9%.

[0160] It has been found that in some applications, a %Moeq of 0.1% to 3.9% is desirable, and in many other applications, a %Moeq of 0.18% to 3.9%, or even 0.8% to 2.8% is desirable.

[0161] The vanadium content is almost always significant in determining most of the relevant properties, as it is almost always present in secondary carbides. When high-temperature hardness is required, %V should not be too low. In some applications of this invention, it has been found desirable for %V to be greater than 0.22%. In some applications of this invention, it has been found desirable for %V to be greater than 0.32%. In some applications of this invention, it has been found desirable for %V to be greater than 0.55%. In some applications of this invention, it has been found desirable for %V to be greater than 0.85%. Also, when high toughness and / or high elongation are required, %V should not be too high. This is true even when the content of carbide formers such as %Mo, %Cr, or %W is high. In some applications of this invention, it is desirable for %V to be less than 1.8%. In some applications of this invention, it is desirable for %V to be less than 1.2%. In some applications of this invention, it is desirable for %V to be less than 0.8%. In some applications of this invention, it is desirable for %V to be less than 0.4%. It has been found that in some applications of the present invention, it is desirable for %V to be less than 0.09%, while in other applications it is desirable for %V to be absent.

[0162] It has been found that in some applications, %V is desired to be between 0% and 1.2%, in many other applications %V is desired to be between 0% and 0.49%, or even 0% and 0.1%, and in some applications %V is desired to be at least 0.01%.

[0163] In some cases, it is desired that the %Ti content is not excessive. In some applications of the present invention, it is desired that %Ti is less than 1.8%. In some applications of the present invention, it is desired that %Ti is less than 1.3%. In other cases, it is desired that %Ti is absent. In other cases, %Ti helps improve the properties of the steel. In such cases, it has been found that %Ti is desired to be more than 0.001%. In such cases, it has been found that %Ti is desired to be more than 0.1%.

[0164] It has been found that in some applications it is desirable for the %Ti to be between 0% and 1.6%, typically between 0% and 0.9%, and in other cases between 0.3% and 0.1%.

[0165] In some cases it is desired that the %Co content is not excessive. In some applications of the present invention it is desired that %Co is less than 2.3%. In some applications of the present invention it is desired that %Co is less than 1.2%. In other cases some applications require that %Co is absent. In other cases %Co helps improve the properties of the steel. In such cases it has been found that %Co is desired to be more than 0.001%. In such cases it has been found that %Co is desired to be more than 0.1%.

[0166] It has been found that in some applications it is desirable for %Co to be between 0% and 2.1%, typically between 0% and 1.7%, and in other cases between 0.01% and 1.3%.

[0167] In some cases it is desired that the %Cu content is not excessive. In some applications of the present invention it is desired that %Cu is less than 1.1%. In some applications of the present invention it is desired that %Cu is less than 0.4%. In other cases some applications may require that %Cu is absent. In other cases %Cu may help improve the properties of the steel. In such cases it has been found that %Cu is desired to be more than 0.001%. In such cases it has been found that %Cu is desired to be more than 0.1%.

[0168] It has been found that in some applications it is desirable for the %Cu to be between 0% and 0.9%, typically between 0% and 0.7%, and in other cases between 0.01% and 0.6%.

[0169] In some cases it is desired that the %Al content is not excessive. In some applications of the present invention it is desired that %Al is less than 0.35%. In some applications of the present invention it is desired that %Al is less than 0.2%. In other cases it is desired that %Al is absent. In other cases %Al helps to improve the properties of the steel. In such cases it has been found that %Al is desired to be more than 0.001%. In such cases it has been found that %Al is desired to be more than 0.1%.

[0170] It has been found that in some applications it is desirable for the %Al to be between 0% and 0.35%, typically between 0% and 0.25%, and in other cases between 0.01% and 0.25%.

[0171] It has been found that in some applications it is desirable for %Cu+%Co+%Al+%Ti>0.01%, typically %Cu+%Co+%Al+%Ti>0.1%, and in other cases %Cu+%Co+%Al+%Ti>0.2%.

[0172] It has been found that in some applications it is desirable for %V+%Al+%Ti>0.001%, typically %V+%Al+%Ti>0.01%, and in other cases %V+%Al+%Ti>0.1%.

[0173] The inventors have discovered that for some compositions, the sum of %Gd + %Nd + %Sm + %Y + %Pr + %Sc + %Pm + %Eu + %Tb + %Dy + %Ho + %Er + %Tm + %Yb + %Lu can be beneficial to the structure of certain inclusions. It has been found that in some applications of the present invention, a sum of %Gd + %Nd + %Sm + %Y + %Pr + %Sc + %Pm + %Eu + %Tb + %Dy + %Ho + %Er + %Tm + %Yb + %Lu greater than 0.2% is required. However, certain values ​​of the sum of %Gd + %Nd + %Sm + %Y + %Pr + %Sc + %Pm + %Eu + %Tb + %Dy + %Ho + %Er + %Tm + %Yb + %Lu can have a detrimental effect on toughness. In some applications of the present invention, it has been found desirable for %Gd+%Nd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb+%Lu to be less than 0.04%. In other applications of the present invention, it has been found desirable for %Gd+%Nd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb+%Lu to be less than 0.008%. In still other applications of the present invention, it has been found desirable for the sum of %Gd+%Nd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb+%Lu to be 0%.

[0174] It has been found that for some compositions %Al, %Ti, %Ta, %Zr, %Hf, %Nb, %Cu, %Co, %La, %Ce and %Cs have a detrimental effect on toughness, in which case it is desirable for %Al, %Ti, %Ta, %Zr, %Hf, %Nb, %Cu, %Co, %La, %Ce and %Cs to be less than 0.38%, in other applications less than 0.18%, in other applications less than 0.08%, and in other applications it is desirable for all %Al, %Ti, %Ta, %Zr, %Hf, %Nb, %Cu, %Co, %La, %Ce and %Cs to be absent.

[0175] In this aspect of the invention, the inventors have demonstrated that a simple dilatometry experiment can select compositions useful in a range of applications involving large cross sections. A dilatometer with repeatability and accuracy better than 0.005%, the ability to resolve increment lengths of 5 nm or greater, and the ability to achieve constant cooling with temperature deviations not exceeding 5°C is desirable. This experiment involves austenitizing a candidate material at 1030°C for at least 20 minutes and cooling to 100°C at a constant cooling rate of 3 K / min. The plot shows d(dL / L) / dt (normalized increment length divided by increment time) versus temperature during cooling. Also, the curve below 600°C is very flat, with a sudden drop at temperature TD (see Figures 1-2: 1-curve plot and 2-TD value sample). In one embodiment, TD is 0.5*10 -4 min -1 is the temperature at which a drop in -4 min -1 In another embodiment, TD is the temperature at which a drop in -4 min -1 In another embodiment, the temperature at which the -4 min -1 The temperature at which a decrease in TD occurs. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is equal to or less than 460°C. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is equal to or less than 419°C. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is equal to or less than 360°C. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is equal to or less than 340°C. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is equal to or less than 318°C. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is equal to or less than 290°C. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is equal to or less than 2740°C. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is equal to or less than 260°C. In some embodiments, the steel composition and thermomechanical treatment are effective when TD is equal to or less than 230°C.

[0176] In the steels of the present invention, it has been found that the microstructure no longer needs to be martensite (tempered martensite), which is much more effective than initially thought. In fact, it is possible to achieve high thicknesses without a martensite structure that provides high toughness. In particular, a bainitic structure is of great interest if the hardness after quenching is at least 8HRc lower than the target hardness after tempering. Therefore, in some embodiments of the present invention, a bainitic microstructure is of great interest (by bainitic is understood the microstructure below the temperature at which existing ferrite or pearlite forms, or above the temperature at which existing martensite forms. For example, Whitmanstatten ferrite is considered bainite in this paper).

[0177] The tool steel of the present invention lends itself to surface heat treatments (superficial tempering, carburizing, nitriding, boriding, etc.) and coatings (PVD, CVD, TD, thermal spray, cold spray, ion implantation, liquid batch, electrochemical, etc.) applicable to AISI H13 steel.

[0178] A 350 mm thick steel having the above composition is heat treated using a method including the following steps: austenitizing at a temperature above 1020°C, after which the steel is subjected to a minimum of three tempering steps, at least one of which must be above 520°C, resulting in a fracture toughness at room temperature of above 51 MPa√m and a hardness of 42-44 HRc.

[0179] The steel of the present invention is particularly useful in additive manufacturing, meaning that the production of powder forms of the steel of the present invention is contemplated.

[0180] The steels of the invention are particularly worthy of consideration for the manufacture of dies and large tools for applications with high thermomechanical demands. Existing methods include aluminum die casting (in the presence of a solid phase (thixotropy) and gravity on a shell at low or high pressure), heavy alloy injection such as Cooper, brass or bronze, as well as all extrusion methods in the case of alloys, forging in open or closed dies, polymer forming (either thermoplastic or thermostable), hot stamping, sheet hot stamping, superplastic deformation of sheets or other low-thickness structures, and many others.

[0181] Another aspect of the present invention is a method for manufacturing a hot work tool. In one implementation, the present invention refers to a method for manufacturing a hot work tool having a layer thickness of more than 303 mm.

[0182] The method is as follows.

[0183] A hot work tool steel having any of the compositions disclosed above is selected.

[0184] If necessary, one or more machining steps and / or heat treatments are applied below the austenitic temperature of the material (including cryogenic treatments).

[0185] A tempering treatment is applied at a temperature above 980°C, which includes at least partial austization.

[0186] If necessary, the material is subjected to a heat treatment below the austenitic temperature of the material and / or one or more machining steps (including cryogenic treatments).

[0187] The material is tempered at least once at a temperature above 520°C.

[0188] If necessary, the material is subjected to a heat treatment below its austenitic temperature and / or one or more machining steps (including cryogenic treatments), and optionally a surface treatment or coating is applied.

[0189] A hardness of over 40 HRc and a fracture toughness of over 51 MPa√m at room temperature are obtained.

[0190] The present invention also has an aspect relating to a method for producing a hot work tool steel, which includes the following steps:

[0191] a) providing a tool steel according to any one of claims 1 to 6.

[0192] b) subjecting the tool steel to a tempering treatment involving at least partial austenitization at a temperature above 980°C;

[0193] c) The material is tempered at least once at a temperature of 520°C or higher.

[0194] This resulted in a hardness of over 40HRc and a fracture toughness of over 51MPa·√m at room temperature.

[0195] If necessary, between a) and b) heat treatment of the material below its austenitic temperature and / or one or more machining steps (including cryogenic treatments) may be applied.

[0196] If necessary, after c), the material may be subjected to a heat treatment below the austenitic temperature of the material and / or one or more machining steps (including cryogenic treatment).

[0197] Deterioration and failure of structures, machine parts, tools and other components is extremely costly. Materials play a crucial role in the long-term durability of many structures and components for machine tools and the like. There has been much research and invention into improved materials for several applications.

[0198] Most applications require only a few specific properties to be high. In many mechanically demanding applications, the environmental, tribological, and thermodynamic requirements are easily met. Even when the mechanical requirements dictate high mechanical strength, a lower level of fracture toughness is acceptable. With technological advances over the past few decades, there has been an ever-increasing need for materials that can simultaneously withstand high mechanical, tribological, environmental, or thermal loads. Price is also a major factor in determining serviceability, and may need to be included as an additional fundamental demand on the material.

[0199] Iron-based alloys or steels, such as so-called high-speed steels and supercarburizing steels, have very high wear resistance. However, they also have limited thermal conductivity, very low resistance to tempering, and do not have high resistance to most oxidizing and corrosive environments, so these materials may lack the ability to withstand high thermal and environmental loads. The high thermal conductivity and achievable tempering resistance of hard metals or other metal matrix carbide composites give them a higher thermal load capacity than other materials within their material family. However, their environmental resistance to oxidizing and corrosive environments remains poor, and cost prohibits them in many cases.

[0200] Although there are iron-based alloys with very high mechanical strength, such as so-called maraging steels, they have poor wear resistance, limited environmental resistance, and limited thermal conductivity.

[0201] Some materials have been developed that have high environmental resistance for certain environments, such as Monel alloys and stainless steels. These present challenges when high friction loads are present and high thermal conductivity is required. In many cases, their cost is also an issue.

[0202] In some cases, the thermal loads require the lowest possible thermal conductivity in the metal. In these cases, titanium-based alloys are sometimes used. However, they lack wear resistance and oxidation resistance at high temperatures, and the associated costs make them unacceptable.

[0203] Over the past few decades, enormous development efforts have been made in the field of multi-materials to satisfy systems that can withstand this complex combination of simultaneous high demands, but in many cases, only the bulk material is required to possess such properties.

[0204] When looking for environmental resistance in steels, there is a strong tendency to rely on a renewable protective film of chromium oxide, which implies a high chromium content (generally more than 10% by weight). However, a high chromium content in steel means a decrease in the achievable compromise between mechanical hardness and toughness. Furthermore, a high chromium content can be associated with a decrease in electrical and thermal conductivity. Furthermore, a high chromium content in an alloy does not result in the desired magnetic, electrical, mechanical and tribological behavior.

[0205] The problem in many cases is that even if one of the highly required resistances is well above par (although sometimes excessive), there are clear shortcomings in other properties required for the application.

[0206] For this reason, bulk materials must simultaneously cope with two or more types of loads: mechanical (mechanical strength, yield strength, fracture toughness, etc.), tribological (adhesion, abrasiveness, corrosion, wear, etc.), mechanical (high thermal conductivity, low thermal conductivity, resistance to softening at high temperatures, etc.) and environmental, especially when environmental requirements must be taken into account.

[0207] The inventors have discovered that a combination of effects can be used to obtain alloys that are resistant to certain destructive environments while maintaining a low chromium content or intentionally eliminating chromium. One method is to add a sufficiently high amount of an iron oxide stabilizer, ideally phosphorus. The second method is to add at least one element that produces a highly insoluble oxide. Suitable elements for providing hard oxides are Ti and Al, but they can be partially or completely replaced by Cr, Zr, Ta, or Hf. Because different oxides behave differently in different media, the choice of insoluble oxide is usually based on the medium to be resisted. A third key element, such as a metal like Cu, Ni, or Mn, may also be added to control the microstructure. This invention can enhance the resistance to certain destructive environments of almost any type of steel and its microstructure. Therefore, key elements are added to the composition in addition to the primary elements to impart specific properties (e.g., mechanical, tribological, electrical, magnetic, thermal, or nuclear properties). When %C (as well as %N and %B) is added to an alloy, the affinity of this element for Ti is so strong that once bound, Ti cannot form a protective titanium oxide. Therefore, to take the behavior into account, either the level of %Ti must be increased or a stronger carbide former must be added to bind the %C. Stronger carbide formers than Ti are Zr, Hf, and Ta.

[0208] Another aspect of the present invention is that it allows for low or even no %Cr while maintaining environmental resistance to certain gases and media. This has a dramatic impact on cost as well as a strong impact on the trade-off between environmental resistance and other properties. When corrosion resistance is also required, most state-of-the-art property combinations do not achieve the highest level. Over the last few years, much development has been done on the bainite structure and the excellent property combinations possible with this microstructure. Higher %Cr amounts either eliminate the bainite domain in the TTT diagram or make it industrially impractical.

[0209] The most widely used solution for obtaining corrosion resistance while maintaining mechanical properties through Cr addition is austenitic stainless steels with approximately 18% Cr, 8% Ni, low C content, and other interstitial atoms. The cost of such alloys is an order of magnitude higher than that of other irons. High-strength sheets can be obtained with the same or better properties, but at a cost that is not as high as that of other irons. With this invention, the minimum cost required to meet environmental resistance requirements can be maintained at the same order of magnitude as other irons.

[0210] The resistance to a particular environment is evaluated electrochemically. In the present invention, a 5% NaCl solution cell and an Ag / AgCl reference electrode are used, with a scan rate of 0.16 mV / s. In the examples in Table 4, various compositions are evaluated against a conventional stainless steel, AISI 316 (example 3.3). All compositions of the present invention exhibit corrosion resistance behavior similar to that of conventional stainless steels, and some (examples 3.1 and 3.5) are even better. Corrosion resistance is evaluated by Taffel plots, where the combination of anodic and cathodic plots allows for direct evaluation of the corrosion rate.

[0211] The inventors have observed that by utilizing a combination of harder and more stable oxides and iron oxide stabilizers, environmental resistance to different environments can be achieved. The key to this invention is ensuring that the desired protective oxide forms on the surface as desired, and for this purpose, it is important that the key elements are present in the desired form. A counterexample illustrates this: if %Ti and %Al are present as the primary protective oxide formers, the alloy contains %C and %Ni, and the alloy is placed in a destructive medium where nearly all of the %Ti and %C combine to form titanium carbides and nearly all of the %A combines with %Ni to form interstitials (NiAl or NiAl), i.e., the alloy is not readily incorporated into the protective oxide film, the alloy will not exhibit the environmental protection properties desired by this invention. Unless special care is taken, the alloy's fortuitous acquisition of these properties is purely coincidental.

[0212] The inventors observed that once iron oxide is stabilized, it becomes easier to build up a protective oxide layer with another oxide that is harder and more stable. Starting with the most economical candidates, Cr, Al, and Ti, the inventors made the following observations:

[0213] The inventors have found that when %C is required to obtain a particular property, special care must be taken to avoid Ti oxidation.

[0214] Sheets, tubes, bars, parts of any shape, profiles, blocks, tubes, powders, wires, rods, etc.

[0215] The inventors have found that if %C is required to obtain the desired properties, care must be taken to ensure that the material used for oxidation of Ti is not affected. The inventors have carried out immersion tests in deionized water and tap water from Rubí, Spain. Resistance to oxidation at high temperatures, and resistance to different acid and basic aqueous solutions have also been investigated.

[0216] According to some literature, the incorporation of %Ti and %P into steels is not a good idea in terms of ductility and toughness. Especially when other elements are present in the composition, with %C and %Ti being typical among those reported, %P promotes strong solid solution strength, but at the same time effectively reduces ductility. Given this fact, the challenge in this invention is to achieve both ductility and toughness, and the alloys of this invention can only be used when the ductility requirement is low. However, if certain rules are observed, this does not necessarily apply, and even very high ductility and toughness values ​​can be reached.

[0217] Both %Ti and %P are strong ferrite stabilizers and if an austenitic microstructure or a microstructure resulting from the decomposition of austenite is desired, other austenite stabilizers must be used. %C is often a powerful agent for this purpose, however, its presence or concentration in the composition is fixed by other criteria (as are %N and %B), and so it often needs to be adjusted with other gamma stabilizers.

[0218] Depending on the nature of the destructive environment, different oxide formers are required to form the protective layer. The types of oxides required are known to be titanium oxide, aluminum oxide, zirconium oxide, chromium oxide, molybdenum oxide, or tungsten oxide. Mixed oxides can also be very effective in compensating for the specific shortcomings of each simple oxide.

[0219] Also, the color obtained with each oxide by anodizing or simple passivation (by natural or artificially obtained weathering) can be a criterion for selecting the oxide-forming elements.

[0220] In applications where the appearance and brightness of stainless steel is to be replicated, the addition of chromium for the formation of a protective oxide is desirable. While no practical limit to chromium addition has been observed in the present invention, it is certainly desirable to practice with lower chromium additions.

[0221] A sufficient amount of oxide former is clearly an amount that allows the formation of a protective oxide layer. Furthermore, in terms of the percentage by weight of the total, iron oxide stabilization is no longer necessary. Depending on the amount required, iron oxide stabilization may not be necessary. However, this depends on the nature of the oxide former. Not requiring iron oxide stabilization means that much less phosphorus is required. Here, low phosphorus includes cases where phosphorus is not present or is present as an impurity. Chromium may be the primary oxide former.

[0222] Most machining applications require high hardness and wear resistance, two of the major drawbacks of Al or Mn alloys. The inventors have discovered that this can be overcome by applying several compositional rules and heat treatments. It is not possible to succinctly describe the applicable heat treatments. Fortunately, however, because microstructural features are at a scale that can be visualized with a microscope, it is more appropriate to define the solution in terms of compositional rules and microstructural characteristics. Generally, a high %Ceq is required to achieve the desired hardness and hard particle volume fraction.

[0223] In some applications the environmental resistance of this alloy can be obtained without the addition of %Al and %Si, while in other applications good oxidation resistance may be required.

[0224] Some applications require non-magnetic behavior, such as plastic injection molding, where the injected polymer contains magnetic particles. For these applications, a usable microstructure is desired, preferably greater than 82% austenite, ideally greater than 93% or even 99% austenite, and a minimum of 55% (not to mention 100%).

[0225] In some high-temperature applications, minimizing heat loss is important, as well as avoiding degradation due to environmental factors. One application where this is achieved is the so-called hot zone in hot stamping. When adapting this application and manufacturing tools from the material described in this invention, it is very important that the material have low thermal conductivity to avoid excessive heat extraction from the product. This low thermal conductivity requires low thermal diffusivity, low density, and low specific heat. In this regard, Al is an alloying element worth considering, as it has a very strong effect on density. For this purpose, to be effective, %Al should be greater than 6.2%, or 7.3%, and preferably greater than 8.3%. Even better, it should be greater than 9.3%, or even 10.4%. To reduce thermal diffusivity, it is desirable to avoid both photon and electron densities in the carbides, and it is even more important to maximize scattering effects in all phases. As described in the references, scattering can be significantly increased by obtaining structures with atomic-level defects. However, these microstructural features (related to the atomic arrangements that optimize carrier density of states and mobility at all stages) are on the sub-nanometer scale. And when we consulted Guideline C-11, 4.11 (current Guideline 2012, Part F, Chapter V, Section 4.11, "Parameters") in writing this application, we found that all available parameters describing these structural features on the sub-nanometer scale were unusual and inappropriate due to their lack of clarity. The only exceptionally clear description of these structural features on the sub-nanometer scale is the thermal conductivity. Therefore, we use this parameter to rationally describe the structural features. For this invention and its applications described above, we have discovered that it is necessary to use structures with thermal conductivities of 10 W / mK or less, or 7.34 W / mK or less, or 6.81 W / mK or less, and more preferably 5.4 W / mK or less. The key to low thermal conductivity in these types of alloys is low thermal diffusivity and, secondarily, low density.Heat capacity has the same effect, and it is recommended to make it as small as possible, but in the present invention it is considered to be kept sufficiently low. In the present invention, the thermal diffusivity is 3.5 mm. 2 / s or less, or 2.6 mm 2 / s, preferably 1.74mm2 / s or 1.46mm 2 / s, and in some applications, it is desirable to have a 2 / s, and the density is required to be less than 6.47 g / cm 3 or less, or 5.21 g / cm 3 or less, or 4.41 g / cm 3 or less, more preferably 3.74 g / cm 3 The values ​​below are required. Obtaining sufficient toughness with such high %Al and %C amounts is a major challenge. High toughness is not required for some applications, and in those cases, no special attention is required. Of course, there are also cases where higher toughness is required, and it has been found that these can be solved by applying the following two methods, either singly or simultaneously. One method is the compositional method, which restricts specific elements. In other words, when %C is greater than 0.74%, or greater than 0.85%, or greater than 0.93%, or greater than 0.96%, and preferably greater than 1.15%, it is required in such applications that %Al be kept at 10.11%, or less than 9.01%, or less than 8.34%, or less than 7.64%, and more preferably less than 6.54%.

[0226] Another approach is through microstructure, which involves minimizing or, if possible, avoiding the formation of weak microstructure. It is recommended that weak microstructure be kept below 38%, or below 24%, or below 13%, or, more preferably, below 8%. In particularly demanding applications, weak microstructure is kept below 5%, or eliminated if possible.

[0227] When designing an alloy, several considerations and alloying rules must be taken into account. Those most relevant to solving the technical problem are explained in the adjacent paragraphs. However, these usually must be compatible with other performance-related properties of the material. The inventors have discovered that, if the final requirements are met, it is possible to obtain a compromise between the other properties by taking some rules into account.

[0228] For the alloys listed above, it is possible to find generalized heat treatments that allow for a reasonable compromise between environmental destructive resistance, hardness, wear resistance, and low thermal conductivity. There are several heat treatments of this type that can be applied, particularly when certain properties are more important than others. That is, when low thermal conductivity is far more important than hardness or wear resistance, a completely different heat treatment is used, and the method selected in each case depends on the chemical composition of the alloy. Depending on the end use, these heat treatments require precipitation at at least 500°C, or above 550°C, or above 600°C, and preferably above 675°C. However, it is recommended to keep this temperature below 850°C, or below 750°C, or below 725°C, and more preferably below 700°C. To further increase hardness, a second precipitation at temperatures above 300°C, 350°C, or above 400°C, and preferably above 450°C, is worth considering. However, it is recommended that the temperature be kept below 700°C, or below 650°C, or below 600°C, and in some cases below 575°C. Depending on the process selected for the material, an annealing treatment is recommended after one of the thermomechanical processing steps, such as grinding or forging. Depending on the application, it may be desirable to carry out a high-temperature holding step above 850°C, or above 900°C, or above 960°C, or even preferably above 980°C. However, at the same time, this temperature must be kept below 1200°C, or below 1175°C, or below 1120°C, or even preferably below 1080°C.

[0229] Any of the above applications may correspond to different compositions of steel and may be combined with other compositional implementations described herein in any combination, provided that the respective properties are compatible.

[0230] Thus, in the suitable practice of the invention, the steel has the following composition, all proportions expressed in weight percent:

[0231]

number

[0232] It is worth noting that, metallurgically, the composition of steel is usually given in terms of Ceq, which is defined as carbon itself or nominal carbon, or all elements that have a carbon-like effect on the cubic structure of steel, usually B or N.

[0233] In the present context, other elements refer to any elements that may be added to the base composition of the present invention to obtain any relevant functionality while still providing the specific destructive environmental resistance provided by the present invention. Typically, such elements, singly or in combination, do not exceed 49% by weight of the alloy. Preferably, they are kept below 38%, or below 24%, or below 10%. This includes trace elements.

[0234] For the purposes of this document, unless otherwise specified, a trace element refers to any element present in an amount less than 2%. Depending on the application, a trace element may be present in an amount less than 1.4%, more preferably less than 0.9%, and ideally less than 0.78%. The following elements, whether elemental or compound, may be considered trace elements: H, Li, Na, K, Rb, CsFr, Be, Mg, Ca, Sr, Ba, Ra, Ac, Tc, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Au, Zn, Cd, Hg, Ga, In, Tl, Ge, Sn, Pb, As, Sb, Bi, O, Se, Te, Po, F, Cl, Br, I, At, He, Ne, Ar, Kr, Xe, Rn, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr. In some applications, trace elements, or trace elements in general, can be critical for certain relevant properties (e.g., thermal conductivity or toughness). In such applications, trace elements below 0.4% are appropriate. Alternatively, trace elements below 0.2%, or even 0.14%, are desirable, and ideally below 0.06%. Needless to say, being below a certain amount also includes the absence of an element. In many cases, it is obvious or desirable to have most or all of the trace elements absent. As mentioned above, all trace elements are considered to be a single substance. Therefore, very often, different trace elements have different maximum weight percentage allowances. Trace elements may be intentionally added to achieve specific functions, including cost reduction. Alternatively, their presence (if any) may be unintentional and primarily related to alloying element impurities and waste from alloy production. The reasons for the presence of different trace elements may vary for the same alloy production process.

[0235] The inventors have discovered that for some applications it is desirable for the total trace element content to be 2.0% or less, for other applications it is 1.4% or less, for other applications it is 0.8% or less, for other applications it is 0.2% or less, and for still other applications it is 0.1% or less or 0.06% or less.

[0236] The inventors have also discovered that it is desirable for the content of individual trace elements to be less than 2.0% in some applications, less than 1.4% in others, less than 0.8% in others, less than 0.2% in others, and less than 0.1% or even less than 0.06% in still other applications.

[0237] Depending on the application, the following elements may or may not be present in the composition: Nb, Co, Lu, La, Ce, Nd, Gd, Sm, Y, Pr, Sc, Pm, Eu, Tb, Dy, Ho, Er, Tm or Yb. One or more of these optional elements may be added to the steel in different weight percentages to improve certain properties, but it is not essential to have all of them in the steel's composition at the same time, nor to combine them at their maximum stated contents. In all cases, the sum of all elements in the steel's composition shall equal 100%.

[0238] Generally, in the steels of the present invention, %C is preferably greater than 0.41%, or greater than 0.51%, or greater than 0.59%, more preferably greater than 0.72%. Depending on the final application, %C is preferably greater than 0.82%, or greater than 0.95%, or greater than 1.12%, more preferably greater than 1.20%. If a high %C is required, for example, when wear resistance is more important than other properties, %C is preferably greater than 1.26%, or greater than 1.41%, or greater than 1.62%, more preferably greater than 1.72%. On the other hand, if the %C content is too high, other drawbacks will appear and must be balanced according to the final requirements. For example, if %C is too high, it will be impossible to obtain the desired properties or to completely form carbides (nitrides, borides, oxides or combinations thereof), regardless of the heat treatment applied. Thus, it may be desirable to maintain %C below 4.1%, or below 3.74%, or below 3.12%, and more preferably below 2.41%. In other cases, it may be desirable to maintain %C below 2.28%, or below 2.02%, or below 1.93%, and more preferably below 1.87%. In applications with high demands, such as those requiring high toughness, great care must be taken with the %C content. In such cases, it may be desirable to maintain %C below 1.81%, or below 1.79%, or below 1.63%, and more preferably below 0.52%.

[0239] In many applications, the allowable %C substitution is fairly small, so it is desirable for %C to be greater than 0.62%, preferably greater than 0.76%, more preferably greater than 1.02%, and even more preferably greater than 1.23%. The general %C and %Ceq limits above are directly applicable here.

[0240] A %Ceq of 0.42% to 3.6%, in many cases 0.42% to 2.9%, and in other applications 0.52% to 2.48% has been found to be desirable.

[0241] A %C of 0.42% to 3.6%, in many cases 0.42% to 2.9%, and in other applications 0.52% to 2.48% has been found to be desirable.

[0242] In such cases, the alloys of the present invention may require %N to be greater than 0.008%, or greater than 0.08%, or greater than 0.1%, or greater than 0.3%, depending on the final application. On the other hand, too high a %N may be undesirable in some applications. Therefore, in the present invention, %N must be kept below 0.45%, or less than 0.3%, or less than 0.1%, and more preferably below 0.01%. Also, in some implementations of the present invention, it may be required that %N is absent from the composition.

[0243] In such cases, applications of the alloys of the present invention may require %B to be greater than 0.08%, or greater than 0.3%, or greater than 1.2%, or greater than 2.1%, depending on the final application. On the other hand, in some applications, too high %B is undesirable. Therefore, in the present invention, %B must be kept below 2.8%, or less than 1.7%, or greater than 0.8%, more preferably less than 0.1%. Also, in some implementations of the present invention, it may be required that %B is absent from the composition.

[0244] In addition, %Mn is also an important element in controlling the application of the present invention. In the alloy of the present invention, %Mn is required to be greater than 10.1%, or greater than 12.22%, or greater than 13.68%, or greater than 14.35%. Depending on the final application, %Mn is required to be greater than 15.2%, or greater than 17.01%, or greater than 18.35%, or greater than 19.71%. In applications where the austenite domain needs to be stable over a wide temperature range, %Mn is required to be greater than 20.31%, or greater than 20.9%, or greater than 22.3%, or greater than 24.9%. On the other hand, %Mn has a strong influence on the processing of steels, so a special amount is required. Therefore, in the present invention, it has been found that %Mn is required to be less than 40.5%, or less than 398%, or less than 37.6%, or less than 36.1%. Depending on the end use, it has been found that %Mn must be kept below 35.3%, or below 32.8%, or below 30.2%, or below 29.3%. In cases where even lower contents are required, it has been found that %Mn must be kept below 28.01%, or below 27.7%, or below 26.9%, or below 26.0%. In some cases, it may be required that %Mn is absent from the composition.

[0245] It has been found that in some applications %Mn is desired to be between 10.1% and 36.4%, in some cases where a higher lower limit of %Mn content is required it may be between 10.6% and 36.4%, and in other cases it may be between 10.6% and 34.6%.

[0246] In applications where Cr and Ni are absent from the composition and %C is less than 1.1%, %Mn less than 34% is desired. Under similar conditions and in applications where %C is less than 0.8%, %Mn less than 16.5% is desired.

[0247] In the alloys of the present invention, %Ni is required to be greater than 0.18%, or greater than 0.59%, or greater than 1.01%, or greater than 1.53%. When quench hardenability is required in the end use, %Ni is required to be greater than 3.2%, or greater than 3.55%, or greater than 4.87%, or greater than 5.46%. Other applications require %Ni greater than 5.88%, or greater than 6.23%, or greater than 6.79%, or greater than 7.49%. On the other hand, too much %Ni is undesirable for some applications. Therefore, it has been found that the present invention requires %Ni to be less than 9.5%, or less than 8.8%, or less than 7.6%, or less than 7.1%. It has been found that the end use requires %Ni to be less than 6.3%, or less than 5.8%, or less than 4.3%, or less than 2.3%. In some applications, such as where thermal conductivity is required, it has been found that %Ni should be kept below 2.1%, or below 1.41%, or below 0.47%, or below 0.12%. In some cases, it may be required that %Ni is absent from the composition.

[0248] It has been found that in some applications %Ni is required to be between 0% and 9.3%, and in other cases %Ni is desired to be between 0.1% and 9.3%, and in other cases 0.1% and 8%, where a lower limit of %Ni is required to be at least 0.1%.

[0249] In some applications it may be desired that %Ni is greater than 0.01%, and in certain applications it is required that %C is less than 1.65% and %Al is between 0.4% and 6.1% and %Ni > 0.1. When %C is greater than 1% and %Si is less than 0.45%, it is desired that %Ni is greater than 0.1%.

[0250] When %C is less than 1.55% and %Al is greater than 2%, %Ni is desired to be greater than 0.1%. When %C is less than 0.65% and %V is greater than 1.1%, %Ni is desired to be greater than 2.1%. Also, in certain applications where %C is less than 1.65% and %Al is less than 6.1%, %Ni is desired to be greater than 4.1%.

[0251] Another element used as a carbide former is %Cr. When used for its final purpose, some implementations require %Cr to be greater than 0.85%, or greater than 2.4%, or greater than 3.6%. Even more demanding applications have been found to require %Cr to be at least 5.57%, or greater than 6.79%, or greater than 6.87%, and more preferably greater than 7.34%. Other implementations may require %Cr to be greater than 8.47%, or greater than 9.4%, or greater than 9.76%. On the other hand, some implementations of the present invention may require %Cr to be less than 9.4%, or less than 8.6%, or less than 8.76%, and more preferably less than 6.7%. Others may require %Cr to be absent from the composition.

[0252] Some applications require that %Cr be present in the composition at least 0.1%. In certain applications, %Cr is desired to be between 0.1% and 9.7%. Other applications may have a %Cr content at the lower or higher end of the desired range. In these cases, %Cr is usually desired to be between 2.3% and 9.3%, and in other applications, 4.1% and 9.1%. Some applications require at least 0.01%Cr, particularly when %Mn>23% or %C<1.3, or both, and in other applications, %Cr>0.1 or %Cr>1.2. In high manganese applications, such as when %Mn>23% or %C<1.3, or both, at least 0.01%Ni is required, and in certain applications, %Ni>0.1 or %Ni>1.2%.

[0253] In particular, in applications where %Cr>4.95% and %C<0.5%, it is desirable to keep the %V content low. In such cases, %V<1.16%, %V<0.9%, or %V<0.7% is sufficient.

[0254] It has been found that it is desirable for %Cr+%Ni to be greater than 0.1%, in other cases %Cr+%Ni > 1.3%, in other cases %Ni+%Cr > 3.8%, and in certain applications %Ni+%Cr > 7.3%.

[0255] It has been found that the desired values ​​of %Ni and %Cr vary depending on the %C content in the steel composition. For some applications where %C is less than 1%, %Cr + %Ni should be greater than 7.4% or even 7.8%. For %C between 1% and 2.2%, %Ni + %Cr should be greater than 0.1%, greater than 0.3% for certain applications, and greater than 1.3% for others.

[0256] When %W is used with other elements to combat wear, it is required that %W be at least 0.55%, or greater than 0.89%, or greater than 1.23%, and more preferably greater than 1.88%. In other implementations, %W is required to be at least 2.22%, or greater than 3.01%, or greater than 3.73%, and more preferably greater than 4.1%. Depending on the desired final properties, %W may be limited to less than 5.2%, or less than 4.6%, or less than 4.1%, and more preferably less than 3.5%, or may even be absent from the composition.

[0257] In some applications, a %W of 0% to 5.9% is desired, while in other applications the %W content may be at the lower or higher end of the desired range, and in such cases, a %W of 0.01% to 4.6%, or 0.1% to 3.9%, has typically been found to be desirable.

[0258] %Mo can also be used as a carbide former. Therefore, %Mo is required to be at least 0.35%, or greater than 0.48%, or greater than 0.99%, and more preferably greater than 1.3%. Other applications require %Mo to be at least 1.8%, or greater than 2.4%, or greater than 2.87%, and more preferably greater than 3.6%. Some applications require %Mo to be less than 6.2%, or less than 5.7%, or less than 4.3%, and more preferably less than 3.3%. Some applications require %Mo to be absent from the composition.

[0259] In some applications, it is desirable for %Mo to be between 0% and 8.4%, while in other applications the %Mo content may be at the lower or higher end of the desired range, and in such cases it has been found that %Mo is typically desirable between 0.01% and 7.6%, or even between 0.1% and 6.3%.

[0260] In some alloys of the present invention, %Co may be required. For example, when resistance to tempering at elevated temperatures is required, %Co may be required to be at least 0.14%, or greater than 0.29%, or greater than 0.54%, more preferably greater than 0.68%. Depending on the desired final properties, %Co may be required to be at least greater than 0.87%, or greater than 0.97%, or greater than 1.26%, more preferably greater than 1.57%. Other applications may require %Co greater than 1.9%, or greater than 2.7%, or greater than 3.2%, more preferably greater than 4.4%. On the other hand, %Co increases the critical cooling rate of the steel, accelerating the pearlitic transformation and thereby reducing the hardenability of the steel. Therefore, too high a %Co may be unsuitable for some applications. In these applications, %Co may be required to be less than 7%, or less than 5.9%, or less than 4.7%, more preferably less than 3.4%. Depending on the desired final properties, %Co may be required to be less than 2.8%, or less than 1.9%, or less than 1.4%, more preferably less than 1.1%. For even lower levels, %Co may be required to be less than 0.89%, or less than 0.6%, or less than 0.44%, more preferably less than 0.12%, or may even be absent from the composition.

[0261] In some applications it is desirable for %Co to be between 0% and 6.4%, while in other applications the %Co content may be at the lower or higher end of the desired range, in which case it has been found that %Co is typically between 0.01% and 5.3%, or 0.1% and 4.6%.

[0262] It has been found that some applications require %Cr+%Cu+%Co to be greater than 0.01%, or typically %Cr+%Cu+%Co>0.1%, while others require %Cr+%Cu+%Co>1.2%, and still others %Cr+%Cu+%Co>3.1%.

[0263] In some steels of the present invention, %Ti may be desired depending on the final requirements. In such cases, %Ti should be at least 0.49%, or greater than 0.68%, or greater than 0.82%, and more preferably greater than 0.99%. In other applications, %Ti should be at least 1.32%, or greater than 1.67%, or greater than 2.11%, and more preferably greater than 2.86%. In more sophisticated applications, %Ti should be greater than 3.5%, or greater than 3.75%, or greater than 4.33%, and more preferably greater than 4.8%. When %Ti is not required, %Ti should be kept below 6.4%, or less than 5.47%, or less than 4.66%, and more preferably less than 3.4%. In addition, in cases where there are high demands under similar conditions, Ti is required to be less than 2.4%, or less than 1.87%, or less than 0.87%, more preferably less than 0.24%, or may be required to be absent from the composition.

[0264] In some applications, it is desirable for the %Ti to be between 0% and 5.9%, while in other applications the %Ti content may be at the lower or higher end of the desired range, and in such cases it has been found that a %Ti of between 0.01% and 5.1%, or even between 0.1% and 3.6%, is typically desirable.

[0265] %Al may also be used in other applications. The inclusion of %Al in the steel of the present invention may be desirable depending on the final requirements. A moderate %Al content may be required, for example, when %Al is used as an enhancer for a characteristic that is more important than other properties, such as hardness. In such cases, %Al should be at least 0.26%, or greater than 0.33%, or greater than 0.43%, and more preferably greater than 0.53%. When low to moderate %Al content is required, such as when %Al is used as a protective coating against oxidation and decarburization at high temperatures, %Al should be maintained around 0.78%, or greater than 1.22%, or greater than 1.54%, and more preferably greater than 2.03%. When moderate %Al content is required, %Al should be at least 2.94%, or greater than 3.47%, or greater than 4.37%, and more preferably greater than 5.39%. When low electrical conductivity is required, a higher %Al content may be required. In such cases, maintaining a low density is effective. In such cases, %Al is required to be greater than 6.2%, 7.3%, 8.3%, or 9.3%, and preferably greater than 10.4%. In cases where Cr is present in the composition, %Al is required to be maintained at 5.4%, or greater than 6.7%, 7.88%, or more preferably greater than 9.01%. In applications where a moderate %Al content is required, such as when oxidation resistance at high temperatures is more important than other environmental resistance, a relatively high %Al content is required, and the presence of other elements such as Si or transition metals is required. In such cases, %Al is required to be greater than 7.64%, 8.27%, or 8.87%, and more preferably greater than 9.8%. In cases where a higher %Al content is required, %Al is required to be greater than 9.51%, 12.44%, or 14.7%, and more preferably greater than 16%. On the other hand, %Al may inhibit certain effects. In such cases, and when other aspects must be taken into consideration, %Al should be kept below 17.5%, 14.36%, or 10.47%, and preferably below 9.31%.In cases where the Al content needs to be moderate, such as when toughness is more important than other properties, Al should be kept to less than 7%, 5.4%, or 4.12%, preferably less than 2.8%. In cases where higher requirements are required, Al should be kept to less than 1.5%, 0.89%, or 0.43%, preferably less than 0.1%. In some cases, Al may be required to be absent from the composition.

[0266] If %C>0.9%, then %Al<10% The condition depends on the application. If %C>0.7%, then %Al<10% This can be replaced with the condition:

[0267] It has been found that for applications where %C is between 0.5% and 1.1% and %Al is greater than 7%, it is desirable for %Mn to be less than 24.8%, and for applications where %C is between 0.5% and 1.1%, %Al is greater than 7%, and %Mn is greater than 23%, it is desirable for %B to be greater than 0.001%.

[0268] Where %Al is required to be at least 0.1%, %Al is required to be 0.1% to 16.7%, or 0.1% to 16.3%, or 0.1% to 15.9%. In particular, for applications where %C<1.52% and %Mn>14.9%, %Al is required to be at least %Al>3.1, and in other cases %Al>3.4.

[0269] It is sometimes required that %Mn be higher than the %Al value. In such cases, when %C is less than 1.65%, it is desirable that %Mn-%Al<10.05%, or %Mn-%Al<9.7%, and in certain cases %Mn-%Al<9.3%.

[0270] Certain applications require %Cr+%Ni+%Al to be greater than 0.1%, and in certain cases greater than 6%, and in certain cases greater than 11%, or even 13%.

[0271] Certain applications require %Cr+%Ni-%Al to be greater than 0.01%, and in certain cases greater than 0.1%.

[0272] Certain applications require %Ni+%Cr+%Al-%Mn to be greater than 0.01% and in certain cases greater than 0.1%.

[0273] If the steel of the present invention requires %Si to achieve specific properties in its final application, %Si must be at least 0.34%, or greater than 0.87%, or greater than 1.06%, or greater than 1.57%. If a high %Si content is required, %Si must be at least 1.99%, or greater than 2.47%, or greater than 3.43%, or greater than 3.87%. If %Si is detrimental to the application, %Si must be less than 4%, or less than 3.4%, or less than 2.4%, or less than 1.8%. If more stringent requirements are made, such as to optimize the cleanliness of the steel or improve toughness, %Si must be less than 1.05%, or less than 0.73%, or less than 0.54%, or less than 0.22%. Or it may be required that %Si is absent from the composition.

[0274] In some applications, %Si is between 0% and 3.4%, and in some cases the lower limit of %Si required is higher, in which case it is known that %Si is desired to be between 0.01% and 2.8%, or 0.1% and 1.8%.

[0275] For applications where %C is greater than 1% and %Si is greater than 0.45%, %Mn-%Al<10 is required.

[0276] Some steels of the present invention require %Cu, and in these cases, %Cu is required to be at least 0.14%, or greater than 0.29%, or greater than 0.54%, and more preferably greater than 0.68%. Depending on the end use, %Cu is required to be at least greater than 0.87%, or greater than 0.97%, or greater than 1.26%, and more preferably greater than 1.57%. Other applications require %Cu to be greater than 1.9%, or greater than 2.7%, or greater than 3.2%, and more preferably greater than 4.4%. On the other hand, some applications do not require high %Cu, and in these cases, %Cu is required to be less than 5.9%, or less than 4.7%, or less than 3.4%. Depending on the end use, %Cu is required to be less than 2.8%, or less than 1.9%, or less than 1.4%, or less than 1.1%. In cases where a lower Cu content is required, Cu may be less than 0.89%, or less than 0.6%, or less than 0.44%, or less than 0.12%, or may even be absent from the composition.

[0277] Some applications require %Cu to be between 0% and 4.8%, and where a low %Cu content is required, it is generally found that %Cu between 0% and 3.1%, or even 0% and 2%, is desirable.

[0278] It has been found that in some applications it is desirable for %Cr+%Cu+%Si to be greater than 0.01%, or for %Cr+%Cu+%Si > 0.1%, in other cases it is desirable for %Cr+%Cu+%Si > 1.2%, and in certain specific applications it is desirable for %Cr+%Cu+%Si > 3.1%.

[0279] Regarding %V, in some applications, %V is required to be at least 0.14%, or greater than 0.57%, or greater than 0.61%, and more preferably greater than 0.69%. In applications with a moderate %V content, %V is required to be at least 0.72%, or greater than 0.83%, or greater than 1.34%, and more preferably greater than 2.46%. When a high %V content is required, in applications with a relatively high %V content, %V is required to be at least 4.11%, or greater than 4.8%, or greater than 5.68%, and more preferably greater than 7.61%. There is also an upper limit to this, and in some applications, %V is required to be less than 12%, or less than 10.98%, or less than 8.74%, or less than 7.36%. In other desired content ranges, %V is required to be less than 5.74%, or less than 3.68%, or less than 2.28%, or less than 1.32%. When a low %V content is required, %V is required to be less than 0.87%, or less than 0.63%, or less than 0.47%, or less than 0.24%. In special cases, %V is required to be less than 0.14%, or less than 0.05%. In implementations where the %C content is high (greater than 0.45%, or more than 0.46%, and more preferably greater than 0.57%), a relatively high value of %V is required. In such cases, %V is required to be at least greater than 0.62%, or more than 0.69%, or more than 0.72%, and more preferably greater than 0.83%. On the other hand, %V is required to be less than 12.3%, or less than 11.4%, or less than 9.47%, or less than 7.68%. When the %Cr content is relatively high, such as 2.71%, or more than 3.15%, or more than 3.87%, or more than 4.99%, or more than 5.21%, the %V is required to be low. In this case, the %V is required to be less than 0.58%, or less than 0.47%, or less than 0.34%, or less than 0.21%. In some cases, it may be required that the %V is absent from the composition.

[0280] The steels of the present invention require that %Al + %Si + %Cr + %V be at least 2%, or greater than 2.31%, or greater than 2.54%, and more preferably greater than 2.87%. In the presence of %Al, %Al + %Si + %Cr + %V be at least greater than 3.1%, or greater than 1.4%, or greater than 3.67%, and more preferably greater than 4%.

[0281] There are cases where Ta, Zr, Hf, Nb, La, and Ce are optional elements in the composition, and there are also cases where one or more of these elements do not need to be contained.

[0282] It may be desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce=0-4.2%.

[0283] Depending on the application, it may be desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce=0-4.2=0-3.7%.

[0284] Depending on the application, it may be desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce=0-4.2=0-2.2%.

[0285] Some applications require %Ta+%Zr+%Hf+%Nb+%La+%Ce to be greater than 0.001%, typically greater than 0.01% in other applications, and greater than 0.1% in other specific applications.

[0286] Depending on the application, it may be desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce=0.001-2.2%. In this case, %P is required to be more than 0.001%, or more than 0.01%, or more than 0.1%, or more than 0.3% depending on the final application. On the other hand, there are cases where too high %P is not desirable, and in such cases in the present invention, %P is required to be less than 1.6%, or less than 1.3%, or less than 0.8%, more preferably less than 0.1%. Or, in some cases, it is required that %P is not present in the composition.

[0287] In this case, %S is required to be more than 0.001%, or more than 0.01%, or more than 0.1%, or more than 0.2% depending on the final application. On the other hand, there are cases where too high %S is not desirable, and in such cases in the present invention, %S is required to be less than 1.6%, or less than 1.3%, or less than 0.8%, more preferably less than 0.1%. Or, in some cases, it is required that %S is not present in the composition.

[0288] It has been found that, depending on the application, values ​​within the following ranges are required:

[0289] %Nb+%Co+%Lu+%La+%Ce+%Nd+%Gd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb=0-10% %Nb+%Co+%Lu+%La+%Ce+%Nd+%Gd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb=0-8% %Nb+%Co+%Lu+%La+%Ce+%Nd+%Gd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb=0-6% It is known that depending on the application, values ​​within the following range are required. %V+%Nb+%Sn+%Si+%Ti+%Co+%W+%Mo=0-9.8% It has been found that some applications require the following minimum contents of elements: %V + %Nb + %Sn + %Si + %Ti + %Co + %W + %Mo = 0.1-9.8%.

[0290] It is common for two different steels to emulate different scientific techniques and therefore to be used in completely different applications. This can result in a range of compositions where one steel is not usable for the other. In most cases, these ranges can interfere with each other, but the actual compositions will never match. Even if such a match does occur, the thermomechanical processing will make a difference.

[0291] The above steels are particularly suitable for applications requiring low thermal conductivity while minimizing heat loss, avoiding hot zones or resisting hostile environments.

[0292] High thermal conductivity may also be required. Because high thermal conductivity is a challenging requirement for typical steels, the present invention is particularly suited to such applications. Because the %Cr content in the present invention is even lower than 10%, a different approach is adopted to achieve high thermal conductivity. Since %Al, a strong oxide former, significantly reduces thermal conductivity, Al content must be avoided as much as possible to maximize its potential. One possible way to achieve this is to limit the primary oxide formers to Zr, or Zr and Nb, or Zr, Nb, and Ti. While other oxide formers are available, their use should be minimized. In the present alloys, where environmental resistance and high thermal conductivity are required, thermal diffusivity is of primary concern, while density and heat capacity are largely negligible.

[0293] On the other hand, there are cases where low thermal conductivity is required. A thermal conductivity of less than 15 W / mK can be achieved with existing stainless steel, but a thermal conductivity of less than 10 W / mK becomes a difficult requirement.

[0294] In some cases, low thermal conductivity is required along with oxidation resistance at high temperatures, in which case a high %Al content is suitable, and for low thermal conductivity, further addition of %Si is recommended.

[0295] A drawback of existing steels that can be easily overcome by the present invention is the inability to combine wear resistance with high hardness, or both, and environmental resistance. Essentially, existing steels have difficulty achieving high wear resistance and a hardness of over 60 HRC. The present invention makes it possible to achieve both these properties and even higher hardness. The hardnesses achievable by the present invention are greater than 47 HRC, or greater than 52 HRC, or greater than 58 HRC, or even greater than 62 HRC.

[0296] The high %Cr content in existing steels makes it almost impossible to obtain a bainite microstructure. In the last few years, there has been progress in the research into this type of microstructure, which could be of advantage to the present invention.

[0297] In some implementations of the present invention, resistance to certain environments can be combined with other mechanical properties, such as high hardness. This hardness can be greater than 48 HRC, or greater than 52 HRC, or greater than 54 HRC, or greater than 58 HRC. These can also be combined with high toughness and wear resistance at carbon contents lower than those of the state of the art. The use of primary carbides, substitutional solid solutions, and / or intermetallic precipitation can be combined to achieve the desired properties. In this context, primary carbides are necessary for wear resistance. However, what is sought is the benefit of toughness from a precipitation-strengthened matrix, keeping %C as low as possible, utilizing carbon content from primary carbides, and achieving the best compromise between hardness and toughness, all of which are considered. In this case, carbides with stronger carbide-forming metals are selected to leave a tougher matrix. Also, harder carbides such as Ti carbides or Ti mixed carbides (mainly with V, W, or Mo) are more suitable here. Alternatively, Zr mixed carbides or Hf mixed carbides can be used instead. The use of minimal secondary carbides in the matrix is ​​also beneficial. With this in mind, precipitates offer a better compromise between hardness and toughness, without increasing %Ceq. Therefore, stronger carbide formers are desirable.

[0298] For the precipitation of intermetallic compounds, Ni3Ti, Ni3Mo, Ni3Al, NiTi, NiMo, or NiAl are well known, and some of these may be used. When Ti or Mo are used in this application, a stronger carbide former must be used to prevent bonding with these carbides. The strongest carbide formers are, in order of strength, Cr, W, Mo, V, Ti, Nb, Ta, Zr, and Hf. This makes it easy to see which is more effective at combining Ti or Mo with Ni while fixing carbon.

[0299] That is, the alloys of the present invention always contain one of the carbide formers, Cr, V, Mo or W.

[0300] Any of the above applications may correspond to different compositions of steel and may be combined with other compositional implementations described herein in any combination, provided that the respective properties are compatible.

[0301] Thus, in the proper practice of the invention, a steel is obtained with the following composition, all proportions expressed in weight percent:

[0302]

number

[0303] For the purposes of this document, unless otherwise specified, a trace element refers to any element present in an amount less than 2%. Depending on the application, a trace element may be present in an amount less than 1.4%, more preferably less than 0.9%, and ideally less than 0.78%. The following elements, whether elemental or compound, may be considered trace elements: H, Li, Na, K, Rb, Fr, Be, Mg, Sr, Ba, Ra, Sc, Y, La, Ac, Tc, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Au, Zn, Cd, Hg, Ga, In, Tl, Ge, O, Po, F, Cl, Br, I, At, He, Ne, Ar, Kr, Xe, Rn, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr. In some applications, trace elements, or trace elements in general, can be critical for certain relevant properties (e.g., thermal conductivity or toughness). In such applications, trace elements below 0.4% are appropriate. Alternatively, trace elements below 0.2%, or even 0.14%, are desirable, and ideally below 0.06%. Needless to say, being below a certain amount also includes the absence of an element. In many cases, it is obvious or desirable to have most or all of the trace elements absent. As mentioned above, all trace elements are considered to be a single substance. Therefore, very often, different trace elements have different maximum weight percentage allowances. Trace elements may be intentionally added to achieve specific functions, including cost reduction. Alternatively, their presence (if any) may be unintentional and primarily related to alloying element impurities and waste from alloy production. The reasons for the presence of different trace elements may vary for the same alloy production process.

[0304] The inventors have discovered that for some applications it is desirable for the total trace element content to be 2.0% or less, for other applications it is 1.4% or less, for other applications it is 0.8% or less, for other applications it is 0.2% or less, and for still other applications it is 0.1% or less or 0.06% or less.

[0305] The inventors have also discovered that it is desirable for the content of individual trace elements to be less than 2.0% in some applications, less than 1.4% in others, less than 0.8% in others, less than 0.2% in others, and less than 0.1% or even less than 0.06% in still other applications.

[0306] Depending on the application, the following elements may or may not be present in the composition: Ta, Zr, Hf, S, Se, Te, Bi, As, Sb, Ca, P, Pb, Cs, Sn or Cu. One or more of these optional elements may be added to the steel in different weight percentages to improve certain properties, but it is not essential to have all of them in the steel's composition at the same time, nor to combine them at their maximum stated contents. In all cases, the sum of all elements in the steel's composition shall equal 100%.

[0307] The required ranges for each element are further described below. For low-carbon applications, %C is preferably around 0.245%, or greater than 0.272%, or greater than 0.301%, and more preferably greater than 0.359%. At the same time, there is an upper limit: %C is required to be less than 0.449%, or less than 0.43%, or less than 0.397%, and more preferably less than 0.356%. For high-carbon applications, %C must be at least 0.451%, or more than 0.47%, or more than 0.54%, or more than 0.64% is more recommended. For other applications, %C is required to be greater than 0.72%, or greater than 0.89%, or greater than 1.21%, and more preferably greater than 1.55%. At the same time, there is a lower limit, and %C must be kept below 2.52%, or below 2.40%, or below 2.273%, preferably below 2.04%. In special cases, %C must be kept below 1.87%, or below 1.67%, preferably below 1.52%.

[0308] It has been found that in some applications it is desirable for the %C to be between 0.26% and 2.5%, typically between 0.31% and 2.5%, and in other cases between 0.35% and 2.5%.

[0309] Regarding %Ceq, in some applications, it is desirable for %Ceq to be maintained around 0.245%, or greater than 0.272%, or greater than 0.301%, and more preferably greater than 0.359%. At the same time, there is an upper limit, and %Ceq is required to be less than 0.449%, or less than 0.43%, or less than 0.397%, and more preferably less than 0.356%. In addition, in applications where %Ceq is high, %Ceq is required to be at least 0.451%, or more preferably greater than 0.47%, or greater than 0.54%, or greater than 0.64%. In other applications, %Ceq is required to be greater than 0.72%, or greater than 0.89%, or greater than 1.21%, and more preferably greater than 1.55%. At the same time, there is an upper limit, and %C is required to be less than 2.52%, or less than 2.40%, or less than 2.273%, preferably less than 2.04%. In special cases, %Ceq is required to be less than 1.87%, or less than 1.67%, preferably less than 1.52%.

[0310] It has been found that in some applications it is desirable for the %Ceq to be between 0.26% and 2.5%, typically between 0.31% and 2.5%, and in other cases between 0.35% and 2.5%.

[0311] Another steel of the invention for the above mentioned applications has the following characteristics:

[0312] When %Ceq=0.45-2.5, %V<0.6; Another steel of the invention for the above mentioned applications has the following characteristics:

[0313] When %Ceq=0.45-2.5, %V=0.01-0.57; If this %C is rather high, for better functionality the %V must be kept below a certain value, typically less than 0.84%, or less than 0.83%, or less than 0.81%, and preferably less than 0.8%.

[0314] In very low carbon implementations of the present invention, the following additions have been found by the inventors to be ideal, depending on the carbide formation required by the final improved characteristics:

[0315] %Cr=2.1-10% when %Ceq=0.25-0.44%; or %Cr=5-10% when %Ceq=0.25-0.44%; or %Ni>4% when %Ceq=0.25-0.44% and %Cr=0.5-5%; or When %Ceq=0.25-0.45%, %Ti+%Hf+%Zr+%Ta+%Al=0.1-4%. In some applications, where %Ceq is between 0.25% and 0.44%, %V must be at least greater than 0.18%, or greater than 0.26%, or greater than 0.43%, or greater than 0.53%. In other applications under similar conditions, the sum of %Ti + %Hf + %Zr + %Ta + %Al should be less than 0.1%, and in many cases less than 0.08%. In other applications where %Ceq is between 0.25% and 0.44%, %Cr should be greater than 5.1%, or greater than 5.49%, or greater than 6.43%, or more preferably 6.77%. In applications where %Cr is kept relatively low, such as between 2.5% and 5%, %Ni may be kept greater than 3.54%, or greater than 3.87%, or greater than 4.03%, or more preferably greater than 4.67%. In other implementations under the same conditions, the sum of %Ti+%Hf+%Zr+%Ta+%Al needs to be adjusted, preferably to 0.1%, or 0.34%, or 0.69%, or slightly more than 0.95%.

[0316] When %W is used as a carbide former, it is recommended that %W be at least 0.15%, or greater than 0.24%, or greater than 0.52%, and more preferably greater than 0.78%. In other embodiments, %W is at least 0.99%, or greater than 1.47%, or greater than 1.96%, and more preferably greater than 2.73%. When a higher %W content is desired, it is recommended that %W be at least 3.47%, or greater than 4.53%, or greater than 6.03%, and more preferably greater than 7.44%. It is also recommended that %W be less than 14.99%, or less than 13.74%, or less than 12.44%, and more preferably less than 11.5%. When the %W content is medium, it is desirable that it be kept below 9.7%, or below 8.64%, or below 7.34%, and more desirably below 6.28%. When the %W content is low, it is required to be below 4.3%, or below 2.7%, or below 1.22%, and more desirably below 0.43%. In some cases, it may be required that %W be below 0.2%, or absent from the composition.

[0317] It has been found that in some applications it is desirable for the %W to be between 0% and 6.8%, typically between 0.01% and 6.8%, and in other cases between 0.01% and 5.8%.

[0318] %Mo can also be used as a carbide former. Therefore, %Mo should be at least 0.14%, or greater than 0.23%, or greater than 0.43%, and more preferably greater than 0.71%. For other applications, %Mo should be at least 1.13%, or greater than 1.26%, or greater than 1.87%, and more preferably greater than 2.46%. When a high %Mo content is required, %Mo should be at least 3.22%, or greater than 4.34%, or greater than 5.23%, and more preferably greater than 6.77%. When a high %Mo content is required, %Mo should be kept below 10%, or less than 7.8%, or less than 6.2%, or less than 4.9%, and more preferably less than 3.31%. When low %Mo content is required, it is desirable that %Mo be kept below 2.8%, or below 1.43%, or below 0.66%, and more preferably below 0.43%. In other cases, %Mo is required to be below 0.24%, or even absent from the composition.

[0319] Some applications require a %Mo content of at least 0.1%, while other applications have found that %Mo is desired to be between 0.1% and 10%, typically between 0.3% and 6.4%, and in other cases between 0.8% and 2.9%.

[0320] Another element used as a carbide former is %Cr. When used for its final purpose, some implementations require a minimum %Cr of more than 2.85%, or more than 3.4%, or more than 5.1%. Even higher %Cr levels have been found to be required, such as at least 5.57%, or more than 6.79%, or more than 6.87%, and more preferably more than 7.34%. Other implementations require %Cr to be more than 8.47%, or more than 9.24%, or more than 9.76%. On the other hand, some implementations of the present invention require %Cr to be less than 13.2%, or less than 9.76%, or less than 8.76%, and more preferably less than 7.44%. When a moderate %Cr content is desired, %Cr may be less than 6.41%, or less than 5.24%, or less than 4.63%, and more preferably less than 3.47%.

[0321] Some applications require %Cr to be present in the composition at 2.5%. In certain applications, %Cr is desired to be between 2.5% and 9.7%. Other applications may have a %Cr content at the lower or higher end of the desired range. In these cases, %Cr is typically between 3.6% and 9.3%, while in other applications, %Cr is desired to be between 5.1% and 9.1%, or even 6.2% and 8.8%.

[0322] With respect to %Co, it has been found that a minimum %Co of greater than 0.13%, or greater than 0.37%, or greater than 0.59%, or greater than 0.87% is required. It has been found that certain end uses require a minimum %Co of greater than 1.33%, or greater than 1.57%, or greater than 1.72%, or greater than 1.92%. It has also been found that certain end uses require a minimum %Co of greater than 2.39%, or greater than 3.41%, or greater than 4.22%, or greater than 5.43%. On the other hand, certain implementations of the present invention may require a %Co of less than 7.89%, or less than 6.4%, or less than 4.92%, more preferably less than 3.82%. It has been found that certain end uses require a %Co of less than 2.43%, or less than 1.94%, or less than 1.53%, more preferably less than 1.07%. When even lower values ​​are required, %Co may be required to be less than 0.54%, or less than 0.43%, or less than 0.24%, or more preferably less than 0.11%, or may be required to be absent from the composition. At the minimum carbon limit, %Co is required to be present according to the following rules:

[0323] If %Ceq=0.25-0.44, then %Co=0.1-4 In applications where there is a minimum carbon limit, a relatively high lower limit for %Co is required. In such applications, the following composition rule applies: If %C=0.25-0.44, then %Co>1.1 It has been found that in applications where %C is between 0.36% and 0.44%, if %V is greater than 0.6%, %Co should be less than 1.9%.

[0324] It has been found that in applications where %C is between 0.25% and 2.5%, %Co is required to be greater than 1.3%, or even greater than 1.40%, and more preferably greater than 1.45%.

[0325] It has been found that in applications where %C is between 0.75% and 1.6%, if %Cr is greater than 4.8%, then %Co is required to be greater than 0.1%.

[0326] In some steels of the present invention, the inclusion of %Ti may be desired depending on the final requirements. In such cases, %Ti is required to be at least 0.08%, or more than 0.68%, or more than 0.82%, and more preferably more than 0.9%. In other applications, %Ti is required to be at least 1.3%, or more than 1.6%, or more than 2.1%, and more preferably more than 2.8%. In more sophisticated applications, %Ti is required to be more than 3.5%, or more than 3.7%, or more than 4.3%, and more preferably more than 4.8%. When %Ti is not required, %Ti should be kept below 6.4%, or less than 5.4%, or less than 4.6%, and more preferably less than 3.4%. In more demanding applications under similar conditions, %Ti should be kept below 2.4%, or less than 1.87%, or less than 0.8%, and more preferably less than 0.24%. Alternatively, it may be required that the compound is not present in the composition.

[0327] In some applications, it is desirable for the %Ti to be between 0% and 2.6%, while in other applications the %Ti content may be at the lower or higher end of the desired range, and in such cases it has been found that a %Ti of between 0% and 1.9%, or even between 0.1% and 1.6%, is usually desirable.

[0328] It has been found that %Al should be at least greater than 0.16%, or greater than 0.24%, or greater than 0.42%, or greater than 0.9%. When higher %Al levels are required, it has been found that %Al should be about 0.93%, with %Al being at least greater than 1.2%, or greater than 1.6%, or greater than 1.8%. In applications requiring even higher levels, it has been found that %Al should be greater than 2.1%, or greater than 2.9%, or greater than 3.53%, or greater than 4.1%. On the other hand, some implementations of the present invention may require %Al to be less than 5%, or less than 4.3%, or less than 3.1%, more preferably less than 2.63%. Some applications may require %Al to be less than 1.3%, or less than 0.9%, or less than 0.8%, more preferably less than 0.6%.

[0329] It has been found that in some applications it is desirable for the %Al to be between 0.5% and 4.8%, typically between 0.6% and 4.8%, and in other cases between 0.7% and 3.8%.

[0330] It has been found that some applications require %Cr-%Al greater than 3.8%, or Cr-%Al greater than 4.1%.

[0331] It has also been found that some applications call for %Co-%Al greater than 0.001% and in other cases typically %Co-%Al greater than 0.01%.

[0332] In certain applications, the following adaptations may be desirable:

[0333] When %Ceq=0.45-2.5, %Ti+%Hf+%Zr+%Ta+%Al=0.1-4. As in the example above, when %Ceq is between 0.25% and 0.45%, %Ti+%Hf+%Zr+%Ta may be kept between 0.1% and 4%.

[0334] On the other hand, in instances where there is a carbon minimum, the following adaptations may be desirable:

[0335] When %Ceq=0.25-0.44, %Ti+%Hf+%Zr+%Ta<0.1% As mentioned above, when %Ceq is between 0.25% and 0.45% and the vanadium content is less than 0.84%, or less than 0.8%, or less than 0.77%, or less than 0.74%, %Ti + %Hf + %Zr + %Ta may be limited to less than 0.1%, or less than 0.08%, depending on the application.

[0336] It has been found that some applications of the above alloys of the present invention require a minimum %Ni of more than 0.21%, or more than 0.48%, or more than 0.87%, or more than 1.28%. Depending on the end purpose of the application, it has been found that %Ni of more than 2.57%, or more than 3.85%, or more than 4.43%, or more than 5.13% is required. Yet other applications have been found to require %Ni of more than 5.97%, or more than 6.43%, or more than 6.93%, or more than 7.28%. On the other hand, some implementations of the present invention may require %Ni of less than 6.3%, more preferably less than 4.7%.

[0337] It has been found that some applications call for %Ni between 3.2% and 12%, or 3.7% and 10.3%, and in other cases %Ni between 4.2% and 9.5%.

[0338] It has been found that the steel of the present invention requires a minimum %Si content of more than 0.01%, or more than 0.13%, or more than 0.22%, or more than 0.38%. When higher contents are required, it has been found that a minimum %Si content of more than 0.67%, or more than 0.87%, or more than 12%, or more than 1.51% is required. In some cases, it may be required to be more than 1.63%. In some implementations of the present invention, where %Si is an inhibitor of the requirements, it may be required to have %Si less than 2%, or less than 1.67%, or less than 1.34%, more preferably less than 0.99%. In more sophisticated cases, %Si should be kept as low as possible. In such cases, it may be required to have %Si less than 0.53%, or less than 0.33%, or less than 0.24%, more preferably less than 0.12%, or even to be absent from the composition.

[0339] It has been found that some applications call for %Si between 0% and 1.8%, or 0% and 1.6%, and in other cases %Si between 0% and 1.4%.

[0340] It has also been found that in some applications where %Si content is required, %Si is required to be between 0.001% and 2%, or between 0.001% and 1.9%, and in other cases %Si is required to be between 0.01% and 1.7%.

[0341] Regarding %Mn, it has been found that certain applications of the alloys of this invention require a minimum %Mn of more than 0.12%, or more than 0.27%, or more than 0.46%, or more than 0.71%. When higher contents are required, it has been found that a minimum %Mn of more than 0.92%, or more than 1.41%, or more than 1.63%, or more desirably more than 2.57% is required. Other applications of this invention may require %Mn to be less than 3.01%, or less than 2.43%, or less than 1.97%, or more desirably less than 1.11%. Depending on the end use, it may require %Mn to be less than 0.94%, or less than 0.73%, or less than 0.62%, or more desirably less than 0.48%. When even lower amounts are required, such as when there is concern about the impairment of certain properties, %Mn may be required to be less than 0.37%, or less than 0.29%, or less than 0.17%, more preferably less than 0.14%, or even absent from the composition.

[0342] It has been found that some applications call for %Mn to be between 0.001% and 3%, or between 0.0015% and 2.7%, and in other cases %Mn to be between 0.01% and 2.4%, and that some applications when %C<0.3 call for %Mn+%Si to be greater than 0.2%, or greater than 0.25%, or greater than 0.3%.

[0343] In applications where the %V content is low, it is known that the %V must be at least 0.14%, or 0.57%, or 0.61%, or even 0.69%. When a medium content is required, the %V must be at least 0.72%.

[0344] If %C is less than 0.3%, it may be more suitable for %Ti to be less than 0.09%.

[0345] In applications where %C is between 0.75% and 1.6%, if %Cr is above 4.8%, %Ni above 5.1% may be more suitable.

[0346] Depending on the application, it may be desirable for %Cr+%V+%Mo+%W to be greater than 2.6%, or greater than 3%, or greater than 4.1%.

[0347] In some applications it is desirable for %Al+%Mo+%Ti to be greater than 0.7%, or greater than 0.9%, and in other cases greater than 1.1%, or even greater than 1.5%.

[0348] That is, the optimum practice of the present invention for the above applications calls for the following alloy compositions:

[0349] %Cr+%V+%Mo+%W>3% and %Al+%Mo+%Ti>0.7% In other applications mentioned above, the best practice is to %Cr+%V+%Mo+%W>3% and %Al+%Mo+%Ti>0.9% In other applications mentioned above, the best practice is to %Cr+%V+%Mo+%W>3% and %Al+%Mo+%Ti>1.1% In other applications mentioned above, the best practice is to %Cr+%V+%Mo+%W>3% and %Al+%Mo+%Ti>1.5% In applications where S and / or Te are present, it has been found desirable for Te / S to be less than 0.04%, and in other cases less than 0.02%.

[0350] In some applications, it has been found that %Si+%Ti+%P+%S+%Mn+%W+%Hf+%Ti+%Cu+%Sn+%Nb+%Pb+%Cs+%Ta=0-9.8% is optimal for the present invention.

[0351] In some applications, if %Ceq=0.25-0.44 and %Ti+%Hf+%Zr+%Ta<0.1, then %V<0.85 It can be replaced by the condition If the conditions are %Ceq=0.25-0.44 and %Ti+%Hf+%Zr+%Ta<0.08, then %V<0.80%.

[0352] If the conditions are %Ceq=0.25-0.44 and %Ti+%Hf+%Zr+%Ta<0.08, then %V<0.78%.

[0353] If the conditions are %Ceq=0.25-0.44 and %Ti+%Hf+%Zr+%Ta<0.08, then %V=0.01-0.80%.

[0354] If the conditions are %Ceq=0.25-0.44 and %Ti+%Hf+%Zr+%Ta<0.08, then %V=0.01-0.78%.

[0355] Some applications benefit from a %Cu content of more than 0.01%. In these cases, %Cu is required to be greater than 0.01%, or greater than 0.1%, or greater than 0.2%, or greater than 0.4%, or greater than 0.6%. In other similar cases, %Cu is required to be greater than 0.8%, or greater than 0.9%, and more preferably greater than 1.1%. More demanding applications require even higher %Cu contents. In these cases, %Cu is required to be at least greater than 1.6%, or greater than 2.4%, or greater than 2.9%, or greater than 3.1%. On the other hand, some applications within the present invention may require %Cu to be less than 3.7%, or less than 3.1%, or less than 2.6%, and more preferably less than 1.9%. Still other applications may require %Cu to be less than 1.4%, or less than 0.8%, or less than 0.6%, and more preferably less than 0.2%. In some cases it is required that %Cu is not present in the composition.

[0356] It has been found that some applications call for %Cu between 0% and 3.4%, or 0% and 1.8%, and in other cases %Cu between 0.01% and 1.6%.

[0357] It has been found that in some applications it is beneficial to have %Cu+%Co+%Al+%Ti>0.6, or %Cu+%Co+%Al+%Ti>0.8, and in other applications %Cu+%Co+%Al+%Ti>1.1.

[0358] Any of the above applications may correspond to different compositions of steel and may be combined with other compositional implementations described herein in any combination, provided that the respective properties are compatible.

[0359] Another suitable implementation of the invention corresponds to a steel having the following composition: All percentages are in weight percent.

[0360]

number

[0361] In the present context, unless otherwise specified, a trace element refers to any element present in an amount less than 2%. Depending on the application, a trace element may be present in an amount less than 1.4%, more preferably less than 0.9%, and ideally less than 0.78%. The elements or compounds H, Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Y, La, Ac, Tc, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Au, Zn, Cd, Hg, Ga, In, Tl, Ge, Sn, Pb, As, Sb, Bi, O, S, Se, Te, Po, F, Cl, Br, I, At, He, Ne, Ar, Kr, Xe, Rn, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr can be considered trace elements. In some applications, trace elements, or trace elements in general, can be critical for certain relevant properties (e.g., thermal conductivity or toughness). In such applications, trace elements below 0.4% are appropriate. Alternatively, trace elements below 0.2%, or even 0.14%, are desirable, and ideally below 0.06%. Needless to say, being below a certain amount also includes the absence of an element. In many cases, it is obvious or desirable to have most or all of the trace elements absent. As mentioned above, all trace elements are considered to be a single substance. Therefore, very often, different trace elements have different maximum weight percentage allowances. Trace elements may be intentionally added to achieve specific functions, including cost reduction. Alternatively, their presence (if any) may be unintentional and primarily related to alloying element impurities and waste from alloy production. The reasons for the presence of different trace elements may vary for the same alloy production process.

[0362] The inventors have discovered that for some applications it is desirable for the total trace element content to be 2.0% or less, for other applications it is 1.4% or less, for other applications it is 0.8% or less, for other applications it is 0.2% or less, and for still other applications it is 0.1% or less or 0.06% or less.

[0363] The inventors have also discovered that it is desirable for the content of individual trace elements to be less than 2.0% in some applications, less than 1.4% in others, less than 0.2% in others, less than 0.8% in others, and less than 0.1% or even less than 0.06% in still other applications.

[0364] Essentially, for the above-mentioned applications of the steel of the present invention, %C should be greater than 0.21%, or greater than 0.51%, or greater than 0.6%, more preferably greater than 0.72%. Depending on the final application, %C should be greater than 0.82%, or greater than 0.9%, or greater than 1.12%, more preferably greater than 1.20%. When a high %C is required, for example, when wear resistance is more important than other properties, %C should be greater than 1.6%, or greater than 2.1%, or greater than 2.8%, more preferably greater than 3.2%. On the other hand, a too high %C content can have other drawbacks, which must be balanced according to the final requirements. For example, a too high %C may make it impossible to obtain the desired properties or to completely form carbides (nitrides, borides, oxides, or a combination thereof), regardless of the heat treatment applied. Therefore, it may be required that %C be kept below 3.4%, or below 2.9%, or below 2.3%, and more preferably below 1.9%. In high-demand applications, such as those requiring high toughness, great care must be taken with the %C content. In such cases, it is required that %C be kept below 1.8%, or below 1.6%, or below 1.2%, and more preferably below 0.9%.

[0365] In general, for the above-mentioned applications of the steel of the present invention, %Ceq is preferably greater than 0.21%, or greater than 0.51%, or greater than 0.59%, more preferably greater than 0.7%. Depending on the end use, %Ceq is preferably greater than 0.8%, or greater than 0.9%, or greater than 1.1%, more preferably greater than 1.2%. When a high %Ceq is required, for example, when wear resistance is more important than other properties, %Ceq is preferably greater than 1.6%, or greater than 2.1%, or greater than 2.8%, more preferably greater than 3.2%. On the other hand, since a too high %Ceq content can cause other drawbacks, a balance must be struck depending on the end requirements. Therefore, it may be necessary to maintain %Ceq below 3.4%, or less than 2.9%, or less than 2.3%, more preferably less than 1.9%. In applications with high demands, such as those requiring high toughness, great care must be taken with the %Ceq content. In such cases, it is desirable to maintain %Ceq below 1.8%, or below 1.6%, or below 1.2%, more preferably below 0.9%.

[0366] In such cases, the composition of the alloy of the present invention described above may require %N to be greater than 0.008%, or greater than 0.08%, or greater than 0.1%, or greater than 0.3%, depending on the final application. On the other hand, too high a %N content may be undesirable in some applications. Therefore, in the present invention, %N must be kept below 0.6%, or less than 0.35%, or less than 0.1%, more preferably less than 0.01%. In addition, in some implementations of the present invention, it may be required that %N is absent from the composition.

[0367] In such cases, applications of the alloys of the present invention described above may require %B to be greater than 0.08%, or greater than 0.3%, or greater than 1.2%, or greater than 2.1%, depending on the final use. On the other hand, too high a %N content may be undesirable in some applications. Therefore, in the present invention, %N must be kept below 2.8%, or less than 1.7%, or greater than 0.8%, more preferably less than 0.1%. Also, in some implementations of the present invention, it may be required that %B is absent from the composition.

[0368] Another element used as a carbide former is %Cr. When used for the final purpose, certain implementations of the above compositions require a minimum %Cr of more than 1.3%, or more than 2.6%, or more than 3.4%. Even higher %Cr levels have been found to be required, such as at least 4.1%, or more than 4.6%, or more than 5.1%, with %Cr being more preferred. Other implementations of the present invention may require %Cr to be more than 6.1%, or more than 6.7%, or more than 7.2%. On the other hand, certain implementations of the present invention may require %Cr to be less than 9.4%, or less than 8.6%, or less than 7.9%, with %Cr being more preferred being less than 6.4%. Implementations requiring lower %Cr levels may require %Cr to be less than 4.4%, or less than 2.7%, or less than 1.9%, or even to be absent from the composition.

[0369] It has been found that certain applications call for %Cr between 0% and 9.7%, in other cases 0% and 8.6%, and in other cases 0% and 7.9%.

[0370] In these cases, applications of the alloys of the present invention require %Ni to be greater than 0.01%, or greater than 0.7%, or greater than 1.1%, or greater than 1.6%. If the end use requires properties such as hardenability, %Ni may be greater than 2.6%, or greater than 3.1%, or greater than 4.6%, or greater than 5.3%. Other applications require %Ni greater than 6.1%, or greater than 6.7%, or greater than 7.1%, or greater than 7.6%. On the other hand, excessively high %Ni may be undesirable for some applications. Therefore, applications of the alloys of the present invention have been found to require %Ni less than 9.8%, or less than 8.4%, or less than 7.3%, or less than 6.9%. Depending on the end use, %Ni may be required to be less than 6.3%, or less than 5.8%, or less than 4.3%, or less than 2.3%. In addition, when thermal conductivity is important, it is known that the Ni content must be kept below 2.1%, below 1.4%, below 0.4%, or below 0.1%. In some cases, it is required that Ni is not present in the composition.

[0371] It has been found that some applications call for %Ni between 0% and 9.6%, or 0% and 8.6%, and in other cases %Ni between 0.01% and 7.9%.

[0372] If the steel of the present invention requires %Si to achieve certain special properties in the final application, %Si is required to be at least 0.01%, or more than 0.1%, or more than 0.3%, or more than 0.6%. If a high %Si content is required, %Si is required to be at least 0.9%, or more than 1.1%, or more than 1.6%, or more than 1.8%. If %Si is detrimental to the application, %Si is required to be less than 2.1%, or less than 1.6%, or less than 1.2%, or less than 0.9%. If more stringent requirements are made, such as optimizing the cleanliness of the steel or improving toughness, %Si is required to be less than 0.8%, or less than 0.6%, or less than 0.2%, or less than 0.1%. Or it may be required that %Si is absent from the composition.

[0373] Some applications require %Si between 0% and 1.9%, while others typically require 0% to 1.4%. Sometimes the lower limit of %Si is required, and in such cases it has been found that %Si between 0.01% and 1.4%, or even 0.1% to 1.2%, is desirable.

[0374] Additionally, %Mn is also an important element in controlling the application of the present invention as described above. In some implementations of the present invention, %Mn is required to be greater than 0.001%, or greater than 0.1%, or greater than 0.3%, or greater than 0.6%. Depending on the end use, %Mn may be required to be greater than 1.2%, or greater than 1.6%, or greater than 2.2%, or greater than 3.1%. It has also been found that the present invention requires %Mn to be less than 5.6%, or less than 4.9%, or less than 4.3%, or less than 2.6%. Depending on the end use, it has been found that the present invention requires %Mn to be less than 1.9%, or less than 1.4%, or less than 0.8%, or less than 0.3%. In some cases, it may be required that %Mn is absent from the composition.

[0375] It has been found that some applications require %Mn between 0% and 4.6%, or between 0% and 3.8%, while other applications require a relatively high lower limit for %Mn, in which case %Mn between 0.01% and 3.9%, or between 0.1% and 3.4% is required.

[0376] %Al may also be used for other purposes. In the steels of the present invention, the inclusion of %Al may be desirable depending on the final requirements. For example, %Al may be used as a promoter of a characteristic that is more important than other properties, such as hardness, and a moderate content may be appropriate. In such cases, %Al should be at least 0.1%, or more than 0.3%, or more than 0.4%, and more preferably more than 0.6%. When a low to moderate content is required, such as when %Al is used as a protective coating against oxidation and decarburization at high temperatures, %Al should be kept around 0.7%, or more than 1.1%, or more than 1.6%, and more preferably more than 1.9%. On the other hand, %Al may hinder certain effects. In such cases, and when other aspects must be taken into consideration, %Al should be kept below 2.3%, or less than 1.9%, or less than 1.4%, and more preferably less than 0.9%. In cases where even higher requirements are made, Al must be kept to less than 0.7%, or less than 0.4%, or less than 0.3%, or more preferably less than 0.1%, or may be required to be absent from the composition.

[0377] It has been found that in some applications it is desirable for the %Al to be between 0% and 1.9%, typically between 0% and 1.6%, and in other cases between 0% and 1.4%. It has also been found that in some applications a %Al content of at least 0.01% is suitable. In these cases, %Al is required to be between 0.01% and 2.4%, or between 0.1% and 2.1%, or even between 0.1% and 1.8%.

[0378] %Mo may be used as a carbide former. In such cases, the steel composition of the present invention requires that %Mo be at least 0.1%, or greater than 0.3%, or greater than 0.9%, more preferably greater than 1.3%. In other applications, %Mo may be at least 1.8%, or greater than 2.4%, or greater than 2.8%, more preferably greater than 3.2%. Depending on the final application, %Mo may be desired to be less than 8.4%, or less than 7.6%, or less than 6.4%, more preferably less than 4.8%. In some cases, it may be desired that %Mo is absent from the composition.

[0379] It has been found that in some applications it is desirable for %Mo to be between 0% and 7.6%, typically between 0% and 6.4%, and in other cases between 0% and 5.6%. In some applications where a relatively high lower limit for %Mo is required, %Mo of 0.01% to 4.6%, or even 0.1% to 3.7% is required.

[0380] When %W is used as a carbide former to combat wear, it is required that %W be at least 0.01%, or greater than 0.3%, or greater than 0.8%, and more preferably greater than 1.1%. In other embodiments, it is required that %W be at least 1.3%, or greater than 1.6%, or greater than 1.9%, and more preferably greater than 2.3%. Depending on the end use, it is also desirable that %W be less than 4.3%, or less than 3.6%, or less than 2.9%, and more preferably less than 2.1%. When a low %W content is desired, it is desirable that %W be less than 1.8%, or less than 1.3%, and more preferably less than 0.8%. In some cases, it is desirable that %W be absent from the composition.

[0381] In some applications, it is desirable for the %W to be between 0% and 4.6%, or between 0% and 3.7%, and in other cases between 0% and 2.8%. Other applications may be at the lower or higher end of the desired range for %W content. In such cases, it has been found that a %W of between 0.01% and 4.6%, or between 0.1% and 3.7%, is typically desirable.

[0382] In some applications of the steel of the present invention, the inclusion of %Ti may be desired depending on the final requirements. In such cases, %Ti is required to be at least 0.01%, or more than 0.1%, or more than 0.3%, more preferably more than 0.6%. In other applications, %Ti is required to be at least 0.8%, or more than 1.1%, or more than 1.3%, more preferably more than 1.6%. When a high %Ti content is not required, %Ti should be kept below 1.8%, or less than 1.4%, or less than 1.1%, more preferably less than 0.8%. In other applications with high requirements under similar conditions, %Ti should be kept below 0.6%, or less than 0.4%, or less than 0.2%, more preferably less than 0.01%. In some cases, %Ti may be absent from the composition.

[0383] In some applications, it is desirable for the %Ti to be between 0% and 1.6%, and in other cases between 0% and 1.3%. Other applications may be at the lower or higher end of the desired range for the %Ti content. In such cases, it has been found that a %Ti of 0.1% to 1.3%, or 0.01% to 0.9% is typically desirable.

[0384] It has also been found that some applications require %Ti+%Nb+%Hf+%Zr+%Ta+%Al to be greater than 0.001%, or even greater than 0.01%, and preferably greater than 0.1%.

[0385] In addition, some applications require %Ti + %Nb + %Hf + %Zr + %Ta + %Al = 0-4, or %Ti + %Nb + %Hf + %Zr + %Ta + %Al = 0.01-4, or %Ti + %Nb + %Hf + %Zr + %Ta + %Al = 0.1-3%.

[0386] In some implementations of the present invention, it may be desired that no %Nb, %Hf, %Zr, or %Ta be present in the composition.

[0387] It has also been found that some applications require %Nb+%Hf+%Zr+%Ta to be greater than 0.001%, or even greater than 0.01%, and preferably greater than 0.1%.

[0388] In addition, in some applications, it is required that %Nb+%Hf+%Zr+%Ta=0-4, or %Nb+%Hf+%Zr+%Ta=0.01-4, or %Nb+%Hf+%Zr+%Ta=0.1-3%.

[0389] Regarding %V, some applications require a %V of at least 0.01%, or greater than 0.1%, or greater than 0.3%, and more preferably greater than 0.9%. For applications requiring a moderate %V content, a %V of at least 1.3%, or greater than 1.9%, or greater than 2.4%, and more preferably greater than 3.1% is required. For applications requiring a high %V content, a %V of at least 3.8%, or greater than 4.3%, or greater than 5.1%, and more preferably greater than 7.3% is required. For some applications, a %V of less than 9.1%, or less than 8.4%, or less than 7.6%, or less than 6.3% is required. For other desired content ranges, a %V of less than 4.9%, or less than 3.7%, or less than 2.8%, or less than 1.6% is required. When a low %V content is required, it may be less than 1.2%, or less than 0.8%, or less than 0.4%, or less than 0.2%. In other cases, it may be less than 0.1%, or less than 0.01%, or it may be required to be absent from the composition.

[0390] It has been found that in some applications, %V is desired to be between 0% and 7.9%, and in many other applications, %V is desired to be between 0% and 6.7%. In cases where a relatively high lower limit of %V is required, %V is desired to be between 0.1% and 8.3%, or 0.01% and 7.2%.

[0391] Depending on the final application, some of the above steel compositions require %Cu, and in such cases, %Cu is required to be at least 0.001%, or greater than 0.01%, or greater than 0.1%, and more preferably greater than 0.4%. In other applications, %Cu is required to be at least greater than 0.6%, or greater than 0.9%, or greater than 1.1%, and more preferably greater than 1.3%. On the other hand, in some applications, a high %Cu is undesirable, and %Cu is required to be less than 1.7%, or less than 1.3%, or less than 0.9%, or less than 0.8%. In even more demanding applications, %Cu is required to be less than 0.6%, or less than 0.3%, or less than 0.1%, or less than 0.09%, or even absent in the composition.

[0392] It has been found that in some applications %Cu is desired to be between 0% and 1.7%, and in many other applications %Cu is desired to be between 0% and 1.2%, and in some applications a relatively high lower limit of %Cu is desired, such as %Cu between 0.01% and 1.4%, or %Ti between 0.01% and 1.2%.

[0393] In some alloys of the present invention, %Co may be required. For example, when resistance to tempering at elevated temperatures is required, %Co may be required to be at least 0.14%, or greater than 0.29%, or greater than 0.54%, more preferably greater than 0.6%. Depending on the desired final properties, %Co may be required to be at least greater than 0.8%, or greater than 0.9%, or greater than 1.2%, more preferably greater than 1.6%. In other applications, %Co may be required to be greater than 1.9%, or greater than 2.7%, or greater than 3.2%, more preferably greater than 4.4%. On the other hand, %Co increases the critical cooling rate of the steel, accelerating the pearlitic transformation and thereby reducing the hardenability of the steel. For this reason, too high a %Co may be unsuitable for some applications. In this application of the present invention, %Co may be required to be less than 6.8%, or less than 5.9%, or less than 4.7%, more preferably less than 3.4%. Depending on the desired final properties, %Co may be required to be less than 2.8%, or less than 1.9%, or less than 1.4%, more preferably less than 1.1%. For even lower levels, %Co may be required to be less than 0.8%, or less than 0.6%, or less than 0.44%, more preferably less than 0.12%, or may even be absent from the composition.

[0394] In some applications it is desirable for %Co to be between 0% and 6.4%, while in other applications the %Co content may be at the lower or higher end of the desired range, in which case it has been found that %Co is typically between 0.01% and 5.3%, or 0.1% and 4.6%.

[0395] In implementing the above steel composition, %P is required to be at least greater than 1.6%, or greater than 1.8%, or greater than 2.1%, and more preferably greater than 2.3%. In other applications requiring a relatively high %P content, %P is required to be at least greater than 2.6%, or greater than 3.2%, or greater than 4.3%, and more preferably greater than 5.1%. In other applications, %P is required to be at least greater than 5.8%, or greater than 6.3%, or greater than 6.9%, and more preferably greater than 7.4%. On the other hand, a high %P is not desired for some applications. In this case, for applications of the above composition, %P is required to be less than 9.2%, or less than 8.6%, or less than 7.4%, or less than 6.8%. Depending on the end use, %P is required to be less than 6.2%, or less than 5.7%, or less than 4.4%, or less than 3.6%. In other cases, %P is required to be less than 2.9%, or less than 2.3%, or less than 2.1%, or less than 1.9%.

[0396] In some applications, a %P of 1.7% to 9.4% is desired, and in other applications, a %P of 1.7% to 8.6%, or 1.9% to 7.9% has typically been found to be desirable.

[0397] It has also been found that in some applications it is beneficial for %Co+%Cu+%V+%Ti+%P>1.6%, and in other cases for %Co+%Cu+%V+%Ti+%P>1.8%, or even %Co+%Cu+%V+%Ti+%P>2.1%.

[0398] It has been found that some applications require %Cu+%Co+%Al+%Ti>0.01%, in other cases %Cu+%Co+%Al+%Ti>0.1%, or even %Cu+%Co+%Al+%Ti>0.2%.

[0399] It has also been found to be beneficial for some applications to have %V+%Al+%Ti>0.001%, or %V+%Al+%Ti>0.01%, and for other applications to have %V+%Al+%Ti>0.1%.

[0400] Some of the above steels have been found to have corrosion resistance greater than or equal to conventional stainless steels.

[0401] Any of the above applications may correspond to different compositions of steel and may be combined with other compositional implementations described herein in any combination, provided that the respective properties are compatible.

[0402] Thus, in another suitable implementation of the invention, the steel has the following composition, all proportions expressed in weight percent:

[0403]

number

[0404] For the purposes of this document, unless otherwise specified, a trace element refers to any element present in an amount less than 2%. Depending on the application, a trace element may be present in an amount less than 1.4%, more preferably less than 0.9%, and ideally less than 0.78%. The following elements, whether elemental or compound, may be considered trace elements: H, Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ac, Tc, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Au, Zn, Cd, Hg, Ga, In, Tl, Ge, Sn, Pb, P, As, Sb, Bi, O, S, Se, Te, Po, F, Cl, Br, I, At, He, Ne, Ar, Kr, Xe, Rn, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, and Lr. In some applications, trace elements, or trace elements in general, can be critical for certain relevant properties (e.g., thermal conductivity or toughness). In such applications, trace elements below 0.4% are appropriate. Alternatively, trace elements below 0.2%, or even 0.14%, are desirable, and ideally below 0.06%. Needless to say, being below a certain amount also includes the absence of an element. In many cases, it is obvious or desirable to have most or all of the trace elements absent. As mentioned above, all trace elements are considered to be a single substance. Therefore, very often, different trace elements have different maximum weight percentage allowances. Trace elements may be intentionally added to achieve specific functions, including cost reduction. Alternatively, their presence (if any) may be unintentional and primarily related to alloying element impurities and waste from alloy production. The reasons for the presence of different trace elements may vary for the same alloy production process.

[0405] The inventors have discovered that for some applications it is desirable for the total trace element content to be 2.0% or less, for other applications it is 1.4% or less, for other applications it is 0.8% or less, for other applications it is 0.2% or less, and for still other applications it is 0.1% or less or 0.06% or less.

[0406] The inventors have also discovered that it is desirable for the content of individual trace elements to be less than 2.0% in some applications, less than 1.4% in others, less than 0.8% in others, less than 0.2% in others, and less than 0.1% or even less than 0.06% in still other applications.

[0407] Depending on the application, the following elements may or may not be present in the composition: Nb, Co, Lu, La, Ce, Nd, Gd, Sm, Y, Pr, Sc, Pm, Eu, Tb, Dy, Ho, Er, Tm or Yb. One or more of these optional elements may be added to the steel in different weight percentages to improve certain properties, but it is not essential to have all of them in the steel's composition at the same time, nor to combine them at their maximum stated contents. In all cases, the sum of all elements in the steel's composition shall equal 100%.

[0408] Essentially, for the above-mentioned applications of the steel of the present invention, %C should be greater than 0.21%, or greater than 0.51%, or greater than 0.6%, more preferably greater than 0.72%. Depending on the final application, %C should be greater than 0.82%, or greater than 0.95%, or greater than 1.12%, or greater than 1.20%. If a high %C is required, for example, where wear resistance is more important than other properties, %C should be greater than 1.26%, more preferably greater than 1.41%, or greater than 1.62%, more preferably greater than 1.72%. On the other hand, a too high %C content can have other drawbacks that must be balanced according to the final requirements. For example, a too high %C may make it impossible to obtain the desired properties or to completely form carbides (nitrides, borides, oxides, or a combination thereof), regardless of the heat treatment applied. Therefore, it may be required that %C be kept below 2.6%, or below 2.02%, or below 1.93%, and more preferably below 1.87%. In high demanding applications, such as those requiring high toughness, great care must be taken with the %C content. In such cases, it is required that %C be kept below 1.81%, or below 1.79%, or below 1.21%, and more preferably below 0.9%.

[0409] In general, for the intended use of the steel of the present invention, %Ceq is preferably greater than 0.21%, or greater than 0.51%, or greater than 0.59%, more preferably greater than 0.72%. Depending on the end use, %Ceq is preferably greater than 0.82%, or greater than 0.95%, or greater than 1.12%, more preferably greater than 1.20%. When a high %Ceq is required, %Ceq is preferably greater than 1.26%, or greater than 1.41%, or greater than 1.62%, more preferably greater than 1.72%. On the other hand, since a too high %Ceq content can cause other drawbacks, a balance must be struck depending on the end requirements. Therefore, %Ceq may need to be maintained below 2.6%, or less than 2.02%, or less than 1.93%, more preferably less than 1.87%. For applications with high demands, such as those requiring high toughness, great care must be taken with the %Ceq content. In such cases, it is desired that %Ceq be maintained below 1.81%, or below 1.79%, or below 1.21%, more preferably below 0.9%.

[0410] In many applications, the allowable %C substitution is fairly small, so it is desirable for %C to be greater than 0.42%, preferably greater than 0.76%, more preferably greater than 1.02%, and even more preferably greater than 1.23%. The general %C and %Ceq limits above are directly applicable here.

[0411] It has been found desirable for the %Ceq to be between 0.42% and 2.7%, in many cases between 0.46% and 2.7%, and in other applications between 0.53% and 2.4%.

[0412] It has been found desirable for the %C to be between 0.42% and 2.7%, in many cases between 0.46% and 2.7%, and in other applications between 0.53% and 2.4%.

[0413] In such cases, the composition of the alloy of the present invention may require %N to be greater than 0.008%, or greater than 0.08%, or greater than 0.1%, or greater than 0.3%, depending on the final application. On the other hand, too high a %N may be undesirable in some applications. Therefore, in the present invention, %N must be kept below 0.45%, or less than 0.3%, or less than 0.1%, more preferably less than 0.01%. In addition, in some implementations of the present invention, it may be required that %N is absent from the composition.

[0414] In such cases, applications of the alloys of the present invention may require %B to be greater than 0.08%, or greater than 0.3%, or greater than 1.2%, or greater than 2.1%, depending on the final application. On the other hand, too high a %N may be undesirable in some applications. Therefore, in the present invention, %B must be kept below 2.8%, or less than 1.7%, or greater than 0.8%, more preferably less than 0.1%. Also, in some implementations of the present invention, it may be required that %B is absent from the composition.

[0415] Additionally, %Mn is also an important element in controlling the application of the present invention. In the alloys of the present invention, %Mn is required to be greater than 0.1%, or greater than 1.2%, or greater than 2.8%, or greater than 3.6%. Depending on the end use, %Mn may be required to be greater than 4.8%, or greater than 6.4%, or greater than 8.4%, or greater than 9.3%. It has also been found that the present invention requires %Mn to be less than 11.2%, or less than 9.7%, or less than 8.6%, or less than 6.4%. It has also been found that depending on the end use, %Mn may be required to be less than 5.2%, or less than 4.8%, or less than 3.6%, or less than 2.8%.

[0416] It has been found that some applications require %Mn between 0% and 9.6%, while other applications require a relatively high lower limit for %Mn, in which cases %Mn between 0.01% and 8.4%, or even between 0.1% and 8.4% is required.

[0417] In the alloy of the present invention, %Ni is required to be greater than 0.18%, or greater than 0.59%, or greater than 1.1%, or greater than 1.53%. If the end use requires properties such as hardenability, %Ni is required to be greater than 3.2%, or greater than 3.6%, or greater than 4.8%, or greater than 5.46%. Other uses require %Ni to be greater than 5.8%, or greater than 6.23%, or greater than 6.79%, or greater than 7%. On the other hand, too much %Ni is undesirable for some applications. Therefore, it has been found that the present invention requires %Ni to be less than 9.6%, or less than 8.8%, or less than 7.6%, or less than 7.1%. It has been found that the end use requires %Ni to be less than 6.3%, or less than 5.8%, or less than 4.3%, or less than 2.3%. In applications where thermal conductivity is required, it has been found that %Ni should be kept below 2.1%, or below 1.41%, or below 0.47%, or below 0.12%. In some cases, it is required that %Ni is absent from the composition.

[0418] It has been found that in some applications %Ni is required to be between 0% and 9.3%, and in other cases %Ni is desired to be between 0.1% and 9.3%, and in other cases 0.1% and 8%, where a lower limit of %Ni is required to be at least 0.1%.

[0419] Another element used as a carbide former is %Cr. When used for the final purpose, certain implementations of the above compositions require a minimum %Cr of greater than 2.3%, or greater than 2.8%, or greater than 3.6%. Even higher %Cr has been found to be required, with %Cr being at least 5.6%, or greater than 6.7%, or greater than 6.8%, and more preferably greater than 7.34%. Other implementations of the present invention may require %Cr to be greater than 8.4%, or greater than 9.24%, or greater than 9.76%. On the other hand, certain implementations of the present invention may require %Cr to be less than 9.4%, or less than 8.6%, or less than 8.76%, and more preferably less than 6.7%.

[0420] Certain applications require %Cr to be between 2.4% and 9.7%. It has been found that in some cases a higher lower limit for %Cr content is suitable, %Cr between 2.8% and 9.3%, and in other cases %Cr between 4.1% and 9.1% is required.

[0421] When %W is used with other elements to combat wear, it is required that %W be at least 0.55%, or greater than 0.89%, or greater than 1.23%, and more preferably greater than 1.8%. In other implementations, %W is required to be at least 2.22%, or greater than 3.1%, or greater than 3.73%, and more preferably greater than 4.1%. Depending on the desired final properties, %W may be limited to less than 5.2%, or less than 4.6%, or less than 4.1%, and more preferably less than 3.5%, or may even be absent from the composition.

[0422] In some applications, a %W of 0% to 5.9% is desired, while in other applications the %W content may be at the lower or higher end of the desired range, and in such cases, a %W of 0.01% to 4.6%, or 0.1% to 3.9%, has typically been found to be desirable.

[0423] %Mo can also be used as a carbide former. Therefore, %Mo is required to be at least 0.35%, or greater than 0.48%, or greater than 0.96%, and more preferably greater than 1.3%. Other applications require %Mo to be at least 1.8%, or greater than 2.4%, or greater than 2.87%, and more preferably greater than 3.6%. Depending on the end use, %Mo may be desired to be less than 5.2%, or less than 4.7%, or less than 3.6%, and more preferably less than 2.8%. In some cases, %Mo may be required to be absent from the composition.

[0424] It has been found that in some applications, %Mo is desired to be between 0% and 5.4%. In some applications, a relatively high lower limit for %Mo is required, such as between 0.01% and 4.6%, or even between 0.1% and 3.7%.

[0425] In some alloys of the present invention, %Co may be required. For example, when resistance to tempering at elevated temperatures is required, %Co may be required to be at least 0.14%, or greater than 0.29%, or greater than 0.54%, more preferably greater than 0.68%. Depending on the desired final properties, %Co may be required to be at least greater than 0.8%, or greater than 0.97%, or greater than 1.26%, more preferably greater than 1.57%. Other applications may require %Co greater than 1.9%, or greater than 2.7%, or greater than 3.2%, more preferably greater than 4.4%. On the other hand, %Co increases the critical cooling rate of the steel, accelerating the pearlitic transformation and thereby reducing the hardenability of the steel. Therefore, too high a %Co may be unsuitable for some applications. In this case, applications of the present invention may require %Co to be kept below 7%, or less than 5.9%, or less than 4.7%, more preferably less than 3.4%. Depending on the desired final properties, %Co may be required to be less than 2.8%, or less than 1.9%, or less than 1.4%, more preferably less than 1.1%. For even lower levels, %Co may be required to be less than 0.89%, or less than 0.6%, or less than 0.44%, more preferably less than 0.12%, or may even be absent from the composition.

[0426] In some applications it is desirable for %Co to be between 0% and 6.4%, while in other applications the %Co content may be at the lower or higher end of the desired range, in which case it has been found that %Co is typically between 0.01% and 5.3%, or 0.1% and 4.6%.

[0427] In some steels of the present invention, %Ti may be desired depending on the final requirements. In such cases, %Ti should be at least 0.49%, or greater than 0.68%, or greater than 0.82%, more preferably greater than 0.99%. In other applications, %Ti should be at least 1.32%, or greater than 1.67%, or greater than 2.11%, more preferably greater than 2.86%. In more sophisticated applications, %Ti should be greater than 3.5%, or greater than 3.75%, or greater than 4.8%, more preferably greater than 4.8%. When %Ti is not required, %Ti should be kept below 6.4%, or less than 5.47%, or less than 4.66%, more preferably less than 3.4%. In addition, in cases where there are high demands under similar conditions, Ti is required to be less than 2.4%, or less than 1.87%, or less than 0.87%, more preferably less than 0.24%, or may be required to be absent from the composition.

[0428] In some applications, it is desirable for %Ti to be between 0% and 4.6%, while in other applications the %Ti content may be at the lower or higher end of the desired range, and in such cases it has been found that %Ti is typically desirable between 0.01% and 4.2%, or even between 0.1% and 3.6%.

[0429] %Al may also be used in other applications. The inclusion of %Al in the steel of the present invention may be desirable depending on the final requirements. A moderate %Al content may be required, for example, when %Al is used as an enhancer for a characteristic that is more important than other properties, such as hardness. In such cases, %Al should be at least 0.26%, or greater than 0.33%, or greater than 0.43%, and more preferably greater than 0.53%. When low to moderate %Al content is required, such as when %Al is used as a protective coating against oxidation and decarburization at high temperatures, %Al should be maintained around 0.78%, or greater than 1.22%, or greater than 1.54%, and more preferably greater than 2.03%. When moderate %Al content is required, %Al should be at least 2.94%, or greater than 3.47%, or greater than 4.37%, and more preferably greater than 5.39%. When low electrical conductivity is required, a higher %Al content may be required. In such cases, it is effective to keep the density low. In such cases, %Al is required to be more than 6.2% or more than 7.3%. On the other hand, %Al may hinder certain effects. In such cases, and when other aspects must be taken into consideration, %Al must be kept below 7%, or below 5.4%, or below 4.12%, more preferably below 2.8%. Furthermore, when even higher requirements are made, %Al must be kept below 1.5%, or below 0.89%, or below 0.43%, more preferably below 0.1%. Or, in some cases, it may be required that %Al is not present in the composition.

[0430] In cases where a minimum %Al of 0.1% is required, it has been found that %Al is required to be between 0.1% and 16.7%, or between 0.1% and 16.3%, or between 0.1% and 15.9%.

[0431] It is sometimes required that %Mn be higher than the %Al value. In such cases, when %C is less than 1.65%, it is desirable that %Mn-%Al<10.05%, or %Mn-%Al<9.7%, and in certain cases %Mn-%Al<9.3%.

[0432] If the steel of the present invention requires %Si to achieve specific properties in its final application, %Si must be at least 0.34%, or greater than 0.87%, or greater than 1.06%, or greater than 1.57%. If a high %Si content is required, %Si must be at least 1.99%, or greater than 2.47%, or greater than 3.43%, or greater than 3.87%. If %Si is detrimental to the application, %Si must be less than 4%, or less than 3.4%, or less than 2.4%, or less than 1.8%. If more stringent requirements are made, such as to optimize the cleanliness of the steel or improve toughness, %Si must be less than 1.05%, or less than 0.73%, or less than 0.54%, or less than 0.22%. Or it may be required that %Si is absent from the composition.

[0433] In some applications, %Si is between 0% and 3.4%, and in some cases the lower limit of %Si required is higher, in which case it is known that %Si is desired to be between 0.01% and 2.8%, or 0.1% and 1.8%.

[0434] Some steels of the present invention require %Cu, and in these cases, %Cu is required to be at least 0.14%, or greater than 0.29%, or greater than 0.54%, and more preferably greater than 0.68%. Depending on the end use, %Cu is required to be at least greater than 0.87%, or greater than 0.97%, or greater than 1.26%, and more preferably greater than 1.57%. Other applications require %Cu to be greater than 1.9%, or greater than 2.7%, or greater than 3.2%, and more preferably greater than 4.4%. On the other hand, some applications do not require high %Cu, and in these cases, %Cu is required to be less than 5.4%, or less than 4.7%, or less than 3.4%. Depending on the end use, %Cu is required to be less than 2.8%, or less than 1.9%, or less than 1.4%, or less than 1.1%. In cases where a lower Cu content is required, Cu may be less than 0.89%, or less than 0.6%, or less than 0.44%, or less than 0.12%, or may even be absent from the composition.

[0435] Some applications require %Cu to be between 0% and 4.8%, and where a low %Cu content is required, it is generally found that %Cu between 0% and 3.1%, or even 0% and 2%, is desirable.

[0436] Regarding %V, in some applications, %V is required to be at least 0.14%, or greater than 0.57%, or greater than 0.61%, and more preferably greater than 0.69%. In applications with a moderate %V content, %V is required to be at least 0.72%, or greater than 0.83%, or greater than 1.34%, and more preferably greater than 2.46%. When a high %V content is required, in applications with a relatively high %V content, %V is required to be at least 4.11%, or greater than 4.8%, or greater than 5.68%, and more preferably greater than 7.61%. There is also an upper limit to this, and in some applications, %V is required to be less than 12%, or less than 10.98%, or less than 8.74%, or less than 7.36%. In other desired content ranges, %V is required to be less than 5.74%, or less than 3.68%, or less than 2.28%, or less than 1.32%. When a low %V content is required, %V is required to be less than 0.87%, or less than 0.63%, or less than 0.47%, or less than 0.24%. In special cases, %V is required to be less than 0.14%, or less than 0.05%. In implementations where the %C content is high (greater than 0.45%, or more than 0.46%, and more preferably greater than 0.57%), a relatively high value of %V is required. In such cases, %V is required to be at least greater than 0.62%, or more than 0.69%, or more than 0.72%, and more preferably greater than 0.83%. On the other hand, %V is required to be less than 12.3%, or less than 11.4%, or less than 9.47%, or less than 7.68%. When the %Cr content is relatively high, such as 2.71%, or more than 3.15%, or more than 3.87%, or more than 4.99%, or more than 5.21%, the %V is required to be low. In this case, the %V is required to be less than 0.58%, or less than 0.47%, or less than 0.34%, or less than 0.21%. In some cases, it may be required that the %V is absent from the composition.

[0437] The steels of the present invention require that %Al + %Si + %Cr + %V be at least 2%, or greater than 2.31%, or greater than 2.54%, and more preferably greater than 2.87%. In the presence of %Al, %Al + %Si + %Cr + %V be at least greater than 3.1%, or greater than 3.4%, or greater than 3.67%, and more preferably greater than 4%.

[0438] It has been found that some applications require %Al+%Si+%Cr+%Ti+%Zr to be a minimum of more than 4.1%, or more than 5.2%, or more than 6.1%, and more preferably more than 8.2%.

[0439] There are cases where Ta, Zr, Hf, Nb, La, and Ce are optional elements in the composition, and there are also cases where one or more of these elements do not need to be contained.

[0440] Depending on the application, it may be desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce=0-4.2%.

[0441] Depending on the application, it may be desirable for the composition to be %Ta+%Zr+%Hf+%Nb+%La+%Ce=0-4.2=0-3.7%.

[0442] Depending on the application, it may be desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce=0-4.2=0-2.2%.

[0443] Some applications desire a minimum of 0.001% Ta + %Zr + %Hf + %Nb + %La + %Ce, others often require a minimum of 0.01%, and still others require Ta + %Zr + %Hf + %Nb + %La + %Ce to be at least 0.1%.

[0444] Depending on the application, it may be desirable for %Ta+%Zr+%Hf+%Nb+%La+%Ce=0.001-2.2%.

[0445] It has been found that some applications require %Cr+%Cu+%Co to be greater than 0.01%, or typically %Cr+%Cu+%Co>0.1%, while others require %Cr+%Cu+%Co>1.2%, and still others %Cr+%Cu+%Co>3.1%.

[0446] It has been found that, depending on the application, values ​​within the following ranges are required:

[0447] %Nb+%Co+%Lu+%La+%Ce+%Nd+%Gd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb=0-10% %Nb+%Co+%Lu+%La+%Ce+%Nd+%Gd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb=0-8% %Nb+%Co+%Lu+%La+%Ce+%Nd+%Gd+%Sm+%Y+%Pr+%Sc+%Pm+%Eu+%Tb+%Dy+%Ho+%Er+%Tm+%Yb=0-6% It has been found that, depending on the application, values ​​within the following ranges are required:

[0448] %V+%Nb+%Sn+%Si+%Ti+%Co+%W+%Mo=0-9.8%. It has been found that some applications require %V+%Nb+%Sn+%Si+%Ti+%Co+%W+%Mo=0-9.8% but at least 0.001%, and %V+%Nb+%Sn+%Si+%Ti+%Co+%W+%Mo=0-9.8% but at least 0.01%, and in other specific applications requires %V+%Nb+%Sn+%Si+%Ti+%Co+%W+%Mo=0-9.8% but at least 0.1%.

[0449] It is also recognized that there are cases where the following minimum values ​​for the following elements are required:

[0450] %V+%Nb+%Sn+%Si+%Ti+%Co+%W+%Mo=0.1-9.8%. Any of the above applications may correspond to different compositions of steel and may be combined with other compositional implementations described herein in any combination, provided that the respective properties are compatible.

[0451] It has been discovered that materials that can be significantly hardened by temperature treatment without quenching are useful in some applications. Furthermore, all temperatures required to harden materials after mechanical processing or molding (including partial molding in a hard state) can be kept below the temperature required for autensitization. This state can be achieved by applying a composition within the following ranges and appropriate heat treatment.

[0452]

number

[0453] %Ceq=%C+0.86*%N+1.2*%B; and %Zreq=%Zr+1 / 2%Hf; and %Moeq=%Mo+1 / 2%W; and %Mn+%Zr+%Ta+%Hf+%Ti>4%. In this document, trace elements refer to any element not specifically listed or present in an amount less than 0.9%. In some applications, trace elements must be present in an amount less than 0.4%, or less than 0.18%, or in other applications, less than 0.06%. As noted above, this includes the complete absence of any element from the composition. Trace elements may be considered to be H, Li, Na, K, Rb, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ac, Tc, Re, Ru, Os, Rh, Ir, Pd, Pt, Ag, Au, Zn, Cd, Hg, B, Ga, In, Tl, Ge, Sn, Pb, P, As, Sb, Bi, O, S, Se, Te, Po, F, Cl, Br, I, At, He, Ne, Ar, Kr, Xe, Rn, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, or compounds thereof. In many applications, the absence of most or all trace elements is evident or desired. As noted above, each trace element is considered a single entity, and therefore, for many applications of the present invention, each trace element has its own allowable amount. Trace elements may be added for functionality as described in the State of the Art section or for cost reduction. Alternatively, the presence of trace elements (if any) may be incidental and related to the lack of purity of the alloying or scrap elements used to produce the material. The reasons for the inclusion of trace elements can vary even within the same alloy.

[0454] The inventors have discovered that for some applications it is desirable for the total trace element content to be 2.0% or less, for other applications it is 1.4% or less, for other applications it is 0.8% or less, for other applications it is 0.2% or less, and for still other applications it is 0.1% or less or 0.06% or less.

[0455] The inventors have also discovered that it is desirable for the content of individual trace elements to be less than 2.0% in some applications, less than 1.4% in others, less than 0.2% in others, less than 0.8% in others, and less than 0.1% or even less than 0.06% in still other applications.

[0456] Carbon equivalent is very important in determining most of the relevant properties. When high wear resistance is required, %Ceq should not be too low. In some implementations of this development, the inventors have found that %Ceq greater than 0.31%, greater than 0.46%, greater than 0.61%, greater than 0.81%, or even greater than 0.92% may be desirable. When high toughness or high elongation, or both, are desired, %Ceq should not be too high. In some implementations of this development, the inventors have found that %Ceq less than 1.98%, or less than 1.48%, is desirable. Furthermore, in other cases, %Ceq less than 0.98%, or less than 0.59% is desired.

[0457] It has also been found that in some applications, %Ceq between 0.22% and 1.49%, in others between 0.22% and 0.88%, and in others between 0.25% and 0.38% is desirable.

[0458] If wear resistance is required, the %C content cannot be too low. In the practice of this invention, it has been found that %C is required to be greater than 0.31%. In the practice of this invention, it has been found that %C is required to be greater than 0.46%. In the practice of this invention, it has been found that %C is required to be greater than 0.61%. In the practice of this invention, it has been found that %C is required to be greater than 0.81%. In the practice of this invention, it has been found that %C is required to be greater than 0.92%. Also, if high toughness or high elongation, or both, are required, it is not required that %C be too high. In the practice of this invention, it is found that %C is required to be less than 1.98%. In the practice of this invention, it is found that %C is required to be less than 1.48%. In the practice of this invention, it is found that %C is required to be less than 0.98%. In the practice of this invention, it is found that %C is required to be less than 0.59%.

[0459] It has been found desirable for %C to be between 0.22% and 1.49%, in other cases between 0.22% and 0.88%, and in other applications between 0.25% and 0.38%.

[0460] For carbon equivalent materials, it may be desirable that the %N content is not too high. In some applications of the present invention, %N less than 0.09% is desirable. In some applications of the present invention, the inventors have found that %N less than 0.004% and in other cases no %N is desirable. In some applications, %N has been found to improve hardenability. In some applications, %N greater than 0.06% has been found to be desirable. In some applications, %N greater than 0.11% has been found to be desirable.

[0461] It is also desirable that the %B content of the carbon equivalent material is not too high. In some applications of the present invention, %B is less than 0.03%. In some applications of the present invention, %B is less than 0.019%. In some applications of the present invention, it has been found that %B is less than 0.009%, and in other applications, %B is absent. It has been found that %B improves hardenability, particularly by inhibiting ferrite transformation. In this case, %B is preferably greater than 0.002%. In this case, %B is preferably greater than 0.0042%. In this case, %B is preferably greater than 0.006%.

[0462] The presence of chromium in secondary carbides almost always plays a major role, and chromium content is therefore crucial in determining most of the related properties. It has been found that %Cr greater than 3.6% is desirable when high-temperature mechanical resistance is required without excessively compromising toughness. In other cases, %Cr greater than 5.2% and in other implementations greater than 6.5% are desired. When high toughness and / or high elongation are desired, it may be desirable to not have too high a %Cr. This is especially important when the content of carbide formers such as %V, %Mo, and %W is high. In some applications, it has been found desirable for %Cr to be less than 9.5%. In some applications, it has been found desirable for %Cr to be less than 8.5%. In some applications, it has been found desirable for %Cr to be less than 4.9%.

[0463] The manganese content is very important in the present invention. The inventors have found that certain %Mn contents, especially in combination with %Zr, %Ti, %Si, %V, or %Cr, can provide significant hardness improvements, even with low-temperature heat treatment. This critical content depends on the specific amounts of other elements in the alloy. For certain applications of the present invention, it has been found desirable for %Mn to be greater than 1.8%. For certain applications of the present invention, it has been found desirable for %Mn to be greater than 3.6%. For certain applications of the present invention, it has been found desirable for %Mn to be greater than 4.6%. For certain applications of the present invention, it has been found desirable for %Mn to be greater than 5.6%. For certain applications of the present invention, it has been found desirable for %Mn to be greater than 6.6%. For certain applications of the present invention, it has been found desirable for %Mn to be greater than 7.6%. Also, depending on the content of other elements in the alloy, it has been found that a high %Mn content can adversely affect the workability of the steel. For certain applications of the present invention, it has been found desirable for %Mn to be less than 9.8%. In certain applications of the present invention, it has been found desirable for %Mn to be less than 7.8%. In certain applications of the present invention, it has been found desirable for %Mn to be less than 5.8%.

[0464] The nickel content plays a very important role, especially in increasing hardness and controlling precipitation. In some applications of the present invention, it has been found desirable for %Ni to be greater than 0.25%. In some applications of the present invention, it has been found desirable for %Ni to be greater than 1.52%. In some applications of the present invention, it has been found desirable for %Ni to be greater than 2.52%. In some applications of the present invention, it has been found desirable for %Ni to be greater than 3.02%. It may be desirable for %Ni to not be too high, especially when toughness is more important than other properties. In some applications of the present invention, it has been found desirable for %Ni to be less than 4.8%. In some applications of the present invention, it has been found desirable for %Ni to be less than 2.78%. In some applications of the present invention, it has been found desirable for %Ni to be less than 0.49%.

[0465] In other cases, it has been found by the inventors that the absence of %Ni in the composition is required.

[0466] The silicon content plays a very important role, especially in increasing hardness and controlling precipitation. It has been found that in some applications of the present invention, %Si is preferably greater than 0.25%. It has been found that in some applications of the present invention, %Si is preferably greater than 1.52%. It has been found that in some applications of the present invention, %Si is preferably greater than 1.82%. It has been found that in some applications of the present invention, %Si is preferably greater than 2.52%. It has been found that in some applications of the present invention, %Si is preferably greater than 3.02%. It has also been found that in the case of the present compositions, too high a %Si content adversely affects the toughness of steels with high layer thicknesses. It has been found that in some applications of the present invention, %Si is preferably less than 0.4%. It has been found that in some applications of the present invention, %Si is preferably less than 0.18%. It has been found that in some applications of the present invention, %Si is preferably less than 0.08%. It has been found that in some applications of the present invention, %Si is preferably less than 0.04%. It has been found by the inventors that the absence of %Si in the composition is desired.

[0467] It has been found that in some compositions, certain values ​​of %Se + %Te + %S + %P + %As + %Pb + %Sb + %Sn can be advantageous for machining. For some applications of the present invention, it has been found that alloy compositions containing %Se + %Te + %S + %P + %As + %Pb + %Sb + %Sn greater than 0.052% are even more desirable. High values ​​of %Se + %Te + %S + %P + %As + %Pb + %Sb + %Sn can be detrimental to toughness. For some applications of the present invention, it has been found that it is desirable for %Se + %Te + %S + %P + %As + %Pb + %Sb + %Sn to be less than 0.04%. For some applications of the present invention, it has been found that it is desirable for %Se + %Te + %S + %P + %As + %Pb + %Sb + %Sn to be less than 0.008%. It is also known that in other applications, it is required that %Se+%Te+%S+%P+%As+%Pb+%Sb+%Sn be 0%.

[0468] In some compositions, it has been found that certain values ​​of %Ta + %Nb can be advantageous for achieving wear resistance. In some applications of the present invention, it has been found that alloy compositions containing %Ta + %Nb greater than 0.22% are desirable. In some applications of the present invention, it has been found that alloy compositions containing %Ta + %Nb greater than 0.54% are desirable. In some applications of the present invention, it has been found that alloy compositions containing %Ta + %Nb greater than 1.6% are desirable. In some applications of the present invention, it has been found that alloy compositions containing %Ta + %Nb greater than 2.04% are desirable. High values ​​of %Ta + %Nb can be detrimental to toughness. In some applications of the present invention, it has been found that %Ta + %Nb less than 0.4% is desirable. In some applications of the present invention, it has been found that %Ta + %Nb less than 0.08% is desirable. In other applications, it has been found that %Ta + %Nb is required to be 0%.

[0469] It has been found that in some compositions, certain values ​​of %Se + %Te can be advantageous for machining. In some applications of the present invention, it has been found that alloy compositions containing %Se + %Te greater than 0.052% are even more desirable. However, certain values ​​of %Se + %Te can have a detrimental effect on the steel of the present invention. In particular, high %Mn contents can interfere with the desired effects of a high %Mn content. In some applications of the present invention, it has been found that %Se + %Te less than 0.19% is desirable. In some applications of the present invention, it has been found that %Se + %Te less than 0.09% is desirable. In some applications of the present invention, it has been found that %Se + %Te less than 0.04% is desirable. In some applications of the present invention, it has been found that %Se + %Te less than 0.008% is desirable. In other applications, it has been found that %Se + %Te is 0%.

[0470] It has been found that in some applications of the present invention, %P + %S is more present in the alloy composition. Depending on the value of %P + %S in a certain composition, it may have a detrimental effect on the steel of the present invention. In particular, when the %Mn content is high, it may interfere with the expected effect of a high %Mn content. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.028%. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.018%. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.008%. It has been found that in some applications of the present invention, %P + %S is desired to be less than 0.0004%. It has been found that in other applications, %P + %S is required to be 0%.

[0471] It has been found that in some applications of the present invention, P is more prevalent in the alloy composition. Some values ​​of %P may have a detrimental effect on the steel of the present invention. In particular, high %Mn contents may interfere with the desired effect of a high %Mn content. It has been found that in some applications of the present invention, %P less than 0.028% is desired. It has been found that in some applications of the present invention, %P less than 0.018% is desired. It has been found that in some applications of the present invention, %P less than 0.008% is desired. It has been found that in some applications of the present invention, %P less than 0.0008% is desired. It has been found that in other applications, %P is required to be 0%.

[0472] It has been found that in some applications of the present invention, S is more prevalent in the alloy composition. Depending on the value of %S, this may have a detrimental effect on the steel of the present invention. In particular, when the %Mn content is high, it may interfere with the expected effect of a high %Mn content. It has been found that in some applications of the present invention, %S is desired to be less than 0.018%. It has been found that in some applications of the present invention, %S is desired to be less than 0.008%. It has been found that in some applications of the present invention, %S is desired to be less than 0.0008%. It has been found that in some applications of the present invention, %S is desired to be less than 0.0004%. It has been found that in other applications, %S is required to be 0%.

[0473] The molybdenum content is almost always significant in determining most relevant properties, as it plays a major role in secondary carbides. When tempering resistance is desired, the molybdenum content should not be too low. In some applications of the present invention, it has been found desirable for %Mo to be greater than 0.16%. In some applications of the present invention, it has been found desirable for %Mo to be greater than 0.21%. In some applications of the present invention, it has been found desirable for %Mo to be greater than 1.1%. Also, when high toughness and / or high elongation are desired, the %Mo should not be too high. This is true even when the content of carbide formers such as %V, %Cr, or %W is high. In some applications of the present invention, it is desirable for %Mo to be less than 0.8%. In some applications of the present invention, it is desirable for %Mo to be less than 0.19%. In some applications of the present invention, it has been found desirable for %Mo to be less than 0.04%, and in other applications, it is desirable for %Mo to be absent.

[0474] For the application of the present invention, it has been found that %Mo can be partially substituted with an amount twice the weight of %W. Also, in some applications, the above %Mo can be substituted with %W, but in that case, the amount must be twice the original %Mo value. In this sense, %Moeq is worthy of consideration as a partial substitute. When used as a substitute, the required amount to be added is expressed as %Moeq = %Mo + 1 / 2 %W. The required value of %Moeq corresponds to the description of %Mo above.

[0475] The zirconium content is almost always significant in determining most relevant properties, as it plays a major role in secondary carbides. When maximizing hardness is desired, the zirconium content should not be too low. In some applications of the present invention, it has been found desirable for %Zr to be greater than 0.22%. In some applications of the present invention, it has been found desirable for %Zr to be greater than 1.2%. In some applications of the present invention, it has been found desirable for %Zr to be greater than 2.55%. In some applications of the present invention, it has been found desirable for %Zr to be greater than 3.25%. Also, when high toughness and / or high elongation are desired, the %Zr should not be too high. This is true even when the content of carbide formers such as %V, %Cr, or %W is high. In some applications of the present invention, it is desirable for %Zr to be less than 6.8%. In some applications of the present invention, it is desirable for %Zr to be less than 4.8%. In some applications of the present invention, it is desirable for %Zr to be less than 2.8%. It has been found that in some applications of the present invention, it is desirable for %Zr to be less than 0.4%, while in other applications it is desirable for %Zr to be absent.

[0476] It has been found that some applications require %Zr to be between 0% and 5.4%, or between 1.2% and 4.4%, and / or between 2.1% and 4.4%.

[0477] For the application of the present invention, it has been found that %Zr can be partially substituted with twice the weight of %Hf. Also, in some applications, %Zr can be substituted with %Hf, but in that case, the amount must be twice the original %Zr value. In this sense, %Zreq is worthy of consideration as a partial substitute. The required amount of addition when used as a substitute is expressed as %Zreq = %Zr + 1 / 2%Hf. The required value of %Zreq corresponds to the description of %Zr above.

[0478] The vanadium content is almost always significant in determining most relevant properties, as it is present in secondary carbides. When hot hardness is desired, %V should not be too low. In some applications of this invention, it has been found desirable for %V to be greater than 0.22%. In some applications of this invention, it has been found desirable for %V to be greater than 0.32%. In some applications of this invention, it has been found desirable for %V to be greater than 0.55%. In some applications of this invention, it has been found desirable for %V to be greater than 1.1%. In some applications of this invention, it has been found desirable for %V to be greater than 2.05%. Also, when high toughness and / or high elongation are desired, %V should not be too high. This is true even when the content of carbide formers such as %Mo, %Cr, or %W is high. In some applications of this invention, it is desirable for %V to be less than 3.8%. In some applications of this invention, it is desirable for %V to be less than 2.8%. In some applications of this invention, it is desirable for %V to be less than 1.8%. It has been found that in some applications of the present invention, a %V of less than 0.4% is desired, while in other applications, no %V is desired.

[0479] The titanium content is almost always significant in secondary carbides and is therefore crucial in determining most of the relevant properties. When hot hardness is desired, %Ti should not be too low. In some applications of this invention, it has been found desirable for %Ti to be greater than 0.22%. In some applications of this invention, it has been found desirable for %Ti to be greater than 0.55%. In some applications of this invention, it has been found desirable for %Ti to be greater than 1.6%. In some applications of this invention, it has been found desirable for %Ti to be greater than 2.6%. In some applications of this invention, it has been found desirable for %Ti to be greater than 3.6%. Also, when high toughness and / or high elongation are desired, %Ti should not be too high. In some applications of this invention, it has been found desirable for %Ti to be less than 4.8%. In some applications of this invention, it has been found desirable for %Ti to be less than 2.8%, and in other applications, it has been found desirable for %Ti to be absent.

[0480] In some cases it is desired that the %Co content is not excessive. In some applications of the present invention it is desired that %Co is less than 2.3%. In some applications of the present invention it is desired that %Co is less than 1.2%. In other cases some applications require that %Co is absent. In other cases %Co helps improve the properties of the steel. In such cases it has been found that %Co is desired to be more than 0.001%. In such cases it has been found that %Co is desired to be more than 0.1%.

[0481] In some cases it is desired that the %Cu content is not excessive. In some applications of the present invention it is desired that %Cu is less than 1.1%. In some applications of the present invention it is desired that %Cu is less than 0.4%. In other cases some applications may require that %Cu is absent. In other cases %Cu may help improve the properties of the steel. In such cases it has been found that %Cu is desired to be more than 0.001%. In such cases it has been found that %Cu is desired to be more than 0.1%.

[0482] In some cases it is desired that the %Al content is not excessive. In some applications of the present invention it is desired that %Al is less than 0.8%. In some applications of the present invention it is desired that %Al is less than 0.2%. In other cases it is desired that %Al is absent. In other cases %Al helps to improve the properties of the steel. In such cases it has been found that %Al is desired to be more than 0.6%. In such cases it has been found that %Al is desired to be more than 1.1%.

[0483] When properly prepared and heat treated at low temperatures, the steel in certain embodiments of this aspect of the invention can achieve a hardness of greater than 8 HRc. When properly prepared and heat treated at low temperatures, the steel in certain embodiments of this aspect of the invention can achieve a hardness of greater than 16 HRc. When properly prepared and heat treated at low temperatures, the steel in certain embodiments of this aspect of the invention can achieve a hardness of greater than 22 HRc. When properly prepared and heat treated at low temperatures, the steel in certain embodiments of this aspect of the invention can achieve a hardness of greater than 32 HRc. When properly prepared and heat treated at low temperatures, the steel in certain embodiments of this aspect of the invention can achieve a hardness of greater than 42 HRc. When properly prepared, the steel in certain embodiments of this aspect of the invention can achieve a hardness of greater than 348 HB. When properly prepared, the steel in certain embodiments of this aspect of the invention can achieve a hardness of greater than 298 HB. When properly prepared, the steel in certain embodiments of this aspect of the invention can achieve a hardness of greater than 248 HB. When properly prepared, the steel in certain embodiments of this aspect of the invention can achieve a hardness of greater than 228 HB. When properly prepared, the steel in one embodiment of this aspect of the invention can achieve a hardness in excess of 348HB. In one embodiment, proper preparation refers to achieving a core temperature of 1020°C, followed by oil quenching, followed by 30 minutes of austenitizing at that temperature. In another embodiment, proper preparation refers to achieving a core temperature of 1020°C, followed by air cooling, followed by 30 minutes of austenitizing at that temperature. In another embodiment, proper preparation refers to achieving a core temperature of 1050°C, followed by oil quenching, followed by 30 minutes of austenitizing at that temperature. In another embodiment, proper preparation refers to achieving a core temperature of 1050°C, followed by air cooling, followed by 30 minutes of austenitizing at that temperature. In another embodiment, proper preparation refers to achieving a core temperature of 1080°C, followed by oil quenching, followed by 30 minutes of austenitizing at that temperature. In one implementation, this refers to achieving a core temperature of 1100°C and then applying air cooling followed by austenitizing at that temperature for 30 minutes.In another embodiment, proper conditioning refers to achieving a core temperature of 1150°C, followed by oil quenching, followed by austenitizing at that temperature for 30 minutes. In another embodiment, proper conditioning refers to achieving a core temperature of 1200°C, followed by air cooling, followed by austenitizing at that temperature for 30 minutes. In another embodiment, proper conditioning refers to achieving a core temperature of 1250°C, followed by oil quenching, followed by austenitizing at that temperature for 30 minutes. In one embodiment of the present invention, low-temperature heat treatment, such as tempering or a similar treatment at 480°C for 4 hours, promotes hardness improvement. The heating and cooling periods are not critical, but they do not need to be particularly rapid. In one embodiment of the present invention, low-temperature heat treatment, such as tempering or a similar treatment at 520°C for 2 hours, promotes hardness improvement. In one embodiment of the present invention, low-temperature heat treatment, such as tempering or a similar treatment at 540°C for 2 hours, promotes hardness improvement. The heating and cooling periods are not critical, but they do not need to be particularly rapid. In some embodiments of the present invention, low-temperature heat treatment, in the sense of tempering or similar treatment at 600°C for 4 hours, promotes hardness improvement. Heating and cooling are not critical, but they do not have to be done particularly quickly. In some embodiments of the present invention, low-temperature heat treatment, in the sense of tempering or similar treatment at 620°C for 4 hours, promotes hardness improvement. Heating and cooling are not critical, but they do not have to be done particularly quickly. In some embodiments of the present invention, low-temperature heat treatment, in the sense of tempering or similar treatment at 520°C for 8 hours, promotes hardness improvement. Heating and cooling are 50K / h.

[0484] In one aspect of the invention, the material of the invention can be formed by a manufacturing process comprising the steps of: -The use of additive manufacturing methods in the production of casting models, intermediate moulds or partial moulds.

[0485] - filling at least a portion of the mold with particulate matter containing at least one metallic phase.

[0486] - Use of cold isostatic pressing (CIP).

[0487] -Removal of the mold.

[0488] -Sintering, hot isostatic pressing (HIP), or other densification at sufficiently high temperatures.

[0489] This forming method is the inventor's best and newest method and the present invention itself. As noted above, the applicability of the present invention to a material must be determined on a case-by-case basis. In addition to the materials described herein, the present invention has been found to be effective with tool steels and high-speed steels. Maraging steels are also considered tool materials herein. In practicing certain aspects of the present invention, steels characterized by %Cr<2.9% and %Moeq>0.8% have been found to be particularly effective. In other cases, steels characterized by %Cr<1.9% and %Moeq>1.6% have been found to be particularly effective. In other cases, steels characterized by %Cr<1.9% and %Moeq>2.6% have been found to be particularly effective. In still other cases, steels characterized by %Cr<0.9% and %Moeq>2.1% have been found to be particularly effective. In still other cases, steels characterized by %Cr<0.3% and %Moeq>3.1% have been found to be particularly effective. It has also been found that this aspect of the invention is effective with bulk wear-resistant particles (tungsten carbide in Ni or Co or alloys of each) and most metal matrix composites (carbides, nitrides, borides, oxides, or mixtures thereof). What has been said herein is applicable to all subsequent aspects and implementations of the invention.

[0490] In this paper, whether the CIP process is dry bagging, wet bagging, warm isostatic pressing, or other similar methods is determined primarily by the actual application, such as the nature, geometry, and availability of the particulate material used. In some implementations, dry bagging is more appropriate, while in others, wet bagging at temperatures above 62°C is more appropriate. In other cases, warm isostatic pressing at temperatures above 82°C is more appropriate, while in other cases, warm isostatic pressing at temperatures above 160°C is more appropriate. In still other cases, warm isostatic pressing at temperatures above 220°C, or even above 450°C, is more appropriate.

[0491] Additive manufacturing processes can be part of the production of a model or mold. In some implementations, additive manufacturing techniques are used to create a model, which is then used in manufacturing of a flexible material (rubber, plastisol, neoprene, or other elastomers). In this case, a first step, additive manufacturing, is applied to produce at least part of the model, where an additional step is added between the first and second steps.

[0492] -The use of additive manufacturing methods in the manufacture of at least partial models.

[0493] - (if necessary) joining the manufactured part with other parts.

[0494] - Production of at least a part of a mould using the model or part of it produced in the previous step and a soft material.

[0495] - filling at least a portion of the mold with particulate matter containing at least one metallic phase.

[0496] - Use of cold isostatic pressing (CIP).

[0497] -Removal of the mold.

[0498] -Sintering, hot isostatic pressing (HIP), or other densification at sufficiently high temperatures.

[0499] In some implementations of the present aspect of the invention, molds are produced by dipping, pouring, painting, or other means where the highly flexible material is above its glass transition temperature. In such cases, it has been found that using a high-temperature resistant polymer in an additive manufacturing process to produce the model is worthy of consideration. In some implementations, it is important that the glass transition temperature be: in some implementations, greater than 85°C; in other cases, greater than 122°C; in other cases, greater than 162°C; in other cases, greater than 202°C; in other cases, greater than 252°C; in other cases, greater than 292°C; or in other cases, greater than 362°C. In some embodiments, the inventors have found that a 0.45 MPa heat distortion temperature is of concern. In some implementations, greater than 125°C; in other cases, greater than 152°C; in other cases, greater than 282°C; in other cases, greater than 232°C; in other cases, greater than 262°C; in other cases, greater than 282°C; or in other cases, greater than 342°C. As with previous sections of this paper, the different properties shown for different implementations can be combined for a given application unless otherwise noted. In this example, a polymer with a sufficiently high transition temperature and a sufficiently high deflection temperature under load at 0.45 MPa may be required. Poly(hydroxybutyl) methacrylate and poly(hydroxyethyl) methacrylate, polyimides, and aromatic polybenzimidazole derivatives are examples of materials that can be used in model fabrication.

[0500] In some implementations of this aspect of the invention, molds are made by dipping, pouring, applying paint, or combining two or more materials to form highly flexible composites followed by a curing process. In these implementations, models can be made using almost any type of material. Any two or more highly elastic materials can be used as components in the mold (e.g., two-component neoprene blends). Other implementations involve the same method as the previous implementation, but require the use of a single-component fluid in a low-temperature solution or emulsion. The solution or emulsion temperature is less than 140°C, or less than 109°C, or less than 98°C, or less than 74°C, and more preferably less than 40°C.

[0501] In one implementation, the mold can be directly manufactured by additive manufacturing using highly flexible materials as the starting material.

[0502] - Use of additive manufacturing methods, at least in part, using soft materials as the base material for the manufacture of moulds or parts thereof.

[0503] - (if necessary) joining the manufactured part with other parts.

[0504] -Pre-mold production using soft materials and models obtained in the previous stage.

[0505] - filling at least a portion of the mold with particulate matter containing at least one metallic phase.

[0506] - Use of cold isostatic pressing (CIP).

[0507] -Removal of the mold.

[0508] -Sintering, hot isostatic pressing (HIP), or other densification at sufficiently high temperatures.

[0509] In this aspect of the invention, a "highly flexible material" is defined as a material that has a high elongation at break. In some embodiments, this is greater than 55%, or greater than 76%, or greater than 92%, or greater than 110%. In other embodiments, this is greater than 160%, or greater than 210%, or greater than 360%, or greater than 576%. Also, when precise dimensions are required or when complex internal cooling or similar networks are desired, a lower hardness limit is required. In some embodiments, this is greater than 72 shore A, or greater than 81 shore A, or greater than 91 shore A, or greater than 102 shore A. In other embodiments, this is greater than 122 shore A, or greater than 181 shore A. Similarly, some applications may require an upper limit on elongation. In some embodiments, this is less than or equal to 390%, or less than or equal to 290%, or less than or equal to 190%, or less than or equal to 140%. In other embodiments, this is less than or equal to 98%. In some cases, the above requirements may be met simultaneously (for example, an elongation at break of greater than 76% but less than 140% and a hardness greater than 81 shore A; the suitability of these combinations varies depending on the application).

[0510] An important series of implementations of the present aspects relate to the fabrication of components with complex internal structures such as channels or other voids that may ultimately be filled with other materials (e.g., cooling channel networks, voids for structural lightening, copper networks for heat treatment, electrical conduction, or signal transmission, etc.). As is well known, the filling or occlusion of these voids is difficult to control with CIP or HIP, and typically requires a simple metal core or mandrel. In this invention, the inventors have shown that it is possible to utilize polymeric materials to create potentially very useful internal void geometries.

[0511] Complex cooling channels and channels filled with other materials can be precisely fabricated in this manner, allowing for conformal cooling strategies.

[0512] In an embodiment of this aspect of the invention, additive manufacturing methods are utilized to produce an intermediate mold or portion thereof, which is then filled with particulate matter comprising at least one metallic phase, followed by: The mold is coated with a mold made of a material with high elasticity (such as a highly elastic material above its glass transition temperature, a multi-component highly elastic material applied at low temperature, or a single-component low-temperature emulsion) produced by any of the methods described above to this effect. This is followed by at least a CIP or similar process and at least one consolidation process at a sufficiently high temperature. The intermediate mold produced by additive manufacturing incorporates most of the cooling channels or other internal features of the component. Because the intermediate mold is filled with particulate matter, it has a geometry similar to the original geometry obtained after solidification of the particulate matter. Shrinkage of the intermediate mold, molds made from highly elastic materials, or compaction of the particulate matter can be considered and corrected by the design process. In some implementations of this aspect of the invention, internal features are minimized or no mechanical processing is performed after consolidation.

[0513] In this aspect of the invention, when an intermediate mold is used, it may be useful to have different interior and exterior features. Here, the interior features are surrounded by the particulate material filling the interior, so they are not subjected to pressure during the CIP process, either directly from the fluid or directly through the preform made of a highly flexible material; this pressure always passes through the surrounding particulate material. Conversely, the exterior features have particulate material on only one side, so the opposite wall is in direct contact with a dry bag, CIP fluid, or the like, possibly through a preform made of a highly flexible material.

[0514] This implementation is diagrammed in Figure 4. The method is as follows.

[0515] - Use of additive manufacturing methods to manufacture intermediate moulds or parts thereof.

[0516] - (Optional) Combine this part of the intermediate mold with the other parts.

[0517] - filling at least a portion of the mold with particulate matter comprising at least one metallic phase.

[0518] - Production of a cover mould from a highly elastic material using the intermediate mould produced in the previous step.

[0519] - Use of cold isostatic pressing (CIP).

[0520] -Removal of the mold.

[0521] -Sintering, hot isostatic pressing (HIP), or other densification at sufficiently high temperatures.

[0522] The filling process and the pre-mold manufacturing process using highly flexible materials can be reversed.

[0523] In some implementations, the average outer layer thickness of the additively manufactured intermediate mold is 1.8 mm or less, in other cases 1.3 mm or less, or 0.8 mm or less, or in other cases 0.4 mm or less, and in other implementations, the average outer layer thickness of the additively manufactured intermediate mold is 1.8 mm or less, or in other cases 0.2 mm or less.

[0524] In some implementations, a sufficiently high temperature for densification means greater than 0.52 Tm, where Tm refers to the lowest melting point of the particulate material. In some implementations, a sufficiently high temperature for densification means greater than 0.62 Tm, where Tm refers to the lowest melting point of the particulate material. In some implementations, a sufficiently high temperature for densification means greater than 0.72 Tm, where Tm refers to the lowest melting point of the particulate material. In some implementations, a sufficiently high temperature for densification means greater than 0.82 Tm, where Tm refers to the lowest melting point of the particulate material. In other cases, it is greater than 0.52 Tm, where Tm refers to the melting point at the maximum volume fraction of the particulate material. In other cases, it is greater than 0.62 Tm, where Tm refers to the melting point at the maximum volume fraction of the particulate material. In other cases, it is greater than 0.72 Tm, where Tm refers to the melting point at the maximum volume fraction of the particulate material. In still other cases, this is greater than 0.82 Tm, where Tm refers to the melting point at the maximum volume fraction of particulate material. In still other cases, this is greater than 0.52 Tm, where Tm refers to the melting point at the maximum weight fraction of particulate material. In still other cases, this is greater than 0.62 Tm, where Tm refers to the melting point at the maximum weight fraction of particulate material. In still other cases, this is greater than 0.72 Tm, where Tm refers to the melting point at the maximum weight fraction of particulate material. In still other cases, this is greater than 0.82 Tm, where Tm refers to the melting point at the maximum weight fraction of particulate material. In still other cases, sufficiently high temperature for densification means greater than 980°C. In still other cases, sufficiently high temperature for densification means greater than 1055°C. In still other cases, sufficiently high temperature for densification means greater than 1120°C. In still other cases, sufficiently high temperature for densification means greater than 1160°C. In other cases, sufficiently high temperature for densification means temperatures above 1210°C.

[0525] In some embodiments, the maximum pressure during the CIP cycle is 110 MPa or greater. In some embodiments, the maximum pressure during the CIP cycle is 210 MPa or greater. In some embodiments, the maximum pressure during the CIP cycle is 310 MPa or greater. In some embodiments, the maximum pressure during the CIP cycle is 410 MPa or greater. In some embodiments, the maximum pressure during the CIP cycle is 510 MPa or greater. In some embodiments, the maximum pressure during the CIP cycle is 710 MPa or greater. In some embodiments, the maximum pressure during the CIP cycle is 810 MPa or greater. In some embodiments, the maximum pressure during the CIP cycle is 1010 MPa or greater.

[0526] In some embodiments, the additively manufactured material has 21% or more hardened filler material. In some embodiments, the additively manufactured material has 41% or more hardened filler material. In some embodiments, the additively manufactured material has 51% or more hardened filler material. In some embodiments, the additively manufactured material has 61% or more hardened filler material.

[0527] In some implementations, additive manufacturing materials are characterized by a bulk modulus of 1.1 GPa or greater. In some implementations, additive manufacturing materials are characterized by a bulk modulus of 2.1 GPa or greater. In some implementations, additive manufacturing materials are characterized by a bulk modulus of 3.1 GPa or greater. In some implementations, additive manufacturing materials are characterized by a bulk modulus of 3.6 GPa or greater. In some implementations, additive manufacturing materials are characterized by a bulk modulus of 4.1 GPa or greater.

[0528] In another implementation, the additive manufacturing material is characterized by an elastic strength of 45 MPa or greater. In another implementation, the additive manufacturing material is characterized by an elastic strength of 55 MPa or greater. In another implementation, the additive manufacturing material is characterized by an elastic strength of 65 MPa or greater. In another implementation, the additive manufacturing material is characterized by an elastic strength of 75 MPa or greater. In another implementation, the additive manufacturing material is characterized by an elastic strength of 85 MPa or greater.

[0529] In some implementations, the method is operated for die casting mold production. In some implementations, the method is operated for die casting mold production with internal cooling. In some implementations, the method is operated for die casting mold production with a method very similar to surface conformal cooling (described in the previous paragraph). In some implementations, the method is operated for die casting mold production with surface conformal cooling and internal heating to reduce thermal gradients.

[0530] In one embodiment, this method is used to make embossing plates. In one embodiment, this method is used in conjunction with internal cooling. In another embodiment, this method is used in conjunction with surface conformal cooling (described below) to make embossing plates. In one embodiment, this method is used in conjunction with conformal cooling to make embossing plates, with the surface temperature kept below 140°C throughout the process. In another embodiment, this method is used in conjunction with conformal cooling to make embossing plates, with the surface temperature kept below 79°C throughout the process. In another embodiment, this method is used in conjunction with conformal cooling to make embossing plates, with the surface temperature kept below 49°C throughout the process. In another embodiment, this method is used in conjunction with conformal cooling to make embossing plates, with the surface temperature kept below 29°C throughout the process. In another embodiment, this method is used to make embossing plates in conjunction with a method very similar to conformal cooling, with the surface temperature maintained below 19°C throughout the entire process. In another embodiment, this method is used to make embossing plates in conjunction with a method very similar to conformal cooling, with the surface temperature maintained below 14°C throughout the entire process. In another embodiment, this method is used to make embossing plates in conjunction with a method very similar to conformal cooling, with the surface temperature maintained above -10°C throughout the entire process. In another embodiment, this method is used to make embossing plates in conjunction with a method very similar to conformal cooling, with the surface temperature maintained above -9°C throughout the entire process, and with the surface temperature maintained above -4°C throughout the entire process. In another embodiment, this method is used to make embossing plates in conjunction with a method very similar to conformal cooling, with the surface temperature maintained above 0.5°C throughout the entire process. In another implementation, this method is used in embossing plate manufacturing with a method very similar to conformal cooling, with the surface temperature maintained above 6°C throughout the entire process.In another embodiment, this method is used in embossing plate making in conjunction with a method very similar to conformal cooling, with the surface temperature maintained above 11°C throughout the entire process. In another embodiment, this method is used in embossing plate making in conjunction with a method very similar to conformal cooling, with the mold surface covered with a uniform film of water prior to hot sheet placement in each cycle. In another embodiment, this method is used in embossing plate making in conjunction with a method very similar to conformal cooling, with the mold surface uniformly sprayed with water or an aqueous solution prior to hot sheet placement in each cycle. In another embodiment, this method is used in embossing plate making in conjunction with a method very similar to conformal cooling, with the mold surface uniformly sprayed with water and air or an aqueous solution prior to hot sheet placement in each cycle. In another embodiment, this method is used in embossing plate making in conjunction with a method very similar to conformal cooling, with the mold surface uniformly sprayed with a fluid or aqueous solution prior to hot sheet placement in each cycle. In another embodiment, this method is used in embossing plate manufacturing with a uniform spray using a nozzle system, in a manner very similar to conformal cooling. In another embodiment, this method is used in embossing plate manufacturing with a uniform spray using some mechanical system, in a manner very similar to conformal cooling. In another embodiment, this method is used in embossing plate manufacturing with a uniform spray using a specific nozzle system or some mechanical system, in a manner very similar to conformal cooling. In yet another embodiment, this method is used in embossing plate manufacturing with a uniform spray using a nozzle system or some mechanical system, in a manner very similar to conformal cooling, with the use of a nozzle system or some mechanical system being changed each cycle.

[0531] In some implementations, the method is used to manufacture forging dies. In some implementations, the method is used to manufacture forging dies with internal cooling. In some implementations, the method is used to manufacture forging dies with a method very similar to surface conformal cooling (described in the previous paragraph). In some implementations, the method is used to manufacture forging dies with surface conformal cooling and internal heating to reduce thermal gradients.

[0532] In some implementations, the method is used to fabricate plastic injection molds. In some implementations, the method is used to fabricate plastic injection molds with internal cooling. In some implementations, the method is used to fabricate plastic injection molds with a method very similar to surface conformal cooling (described in the previous paragraph). In some implementations, the method is used to fabricate plastic injection molds with both surface conformal cooling and internal heating to reduce thermal gradients.

[0533] In one implementation, the method is used to fabricate soft zone dies for internally heated hot stamping. In one implementation, the method is used to fabricate soft zone dies with cartridges for internally heated hot stamping. In another implementation, the method is used through an integrated Joule effect circuit to fabricate soft zone dies with cartridges for internally heated hot stamping. In another implementation, the method is used through an integrated eddy current system to fabricate soft zone dies with cartridges for internally heated hot stamping.

[0534] In some implementations, the particulate material refers to a powder, in some implementations, the particulate material refers to a spherical powder, and in other implementations, the particulate material refers to granules.

[0535] In some implementations, the steel and particulate material are suitable for use in powder form in a powder mixture. Unless otherwise specified, the particle size of the metal powder is D50. For some applications, fine powders are used with a d50 of 78 microns or less. This is preferably 48 microns or less, or 18 microns or less, and more preferably 8 microns or less. For other applications, coarser powders can be used. This requires a d50 of 780 microns or less, or 380 microns or less, or 180 microns or less, and more preferably 120 microns or less. In some implementations, the use of fine powders is not suitable. In these cases, the powders used must have a d50 of 12 microns or more, or 22 microns or more, or 42 microns or more, and more preferably 72 microns or more.

[0536] In some implementations, the powder must be fairly spherical and have a fairly narrow particle size distribution. The sphericity of a powder is a dimensionless number defined as the ratio between the surface area of ​​a sphere having the same volume as the particle and the surface area of ​​that particle. In some implementations, this is required to be greater than 0.53, or greater than 0.76, or greater than 0.86, and more preferably greater than 0.92. In the present invention, high metal particle compaction is required, which requires high sphericity of the metal powder. This is preferably greater than 0.92, or greater than 0.94, or greater than 0.98, or even greater than 1. Regarding sphericity, in some implementations, it can be evaluated by the average sphericity of the most spherical particles in only the majority of the powder. In this case, it is required that 60% or more, or 78% or more, or 83% or more, and more preferably 96% or more of the powder by mass be considered when calculating the average sphericity. In some implementations, it may be more advantageous to have a sphericity of less than 0.94, or less than 0.88, or less than 0.68, or less than 0.48.

[0537] In some embodiments, the steel produced according to the above composition can be produced in powder form. In other embodiments, the powder is spherical. In some embodiments, the spherical steel powder has a particle size (d50) of 200 micrometers or less, in other embodiments 190 micrometers or less, in other embodiments 180 micrometers or less, in other embodiments 90 micrometers or less, and in still other embodiments 45 micrometers or less.

[0538] The present invention employs a highly aggressive cooling method. This cooling method, as mentioned above, is achieved by cooling channels located very close to the surface, which is resistant to corrosion cracking and mechanical failure. This is true even when the channels are machined into rough surfaces. In addition to traditional manufacturing methods such as drilling, brazing, and shell construction, the present invention primarily considers additive manufacturing and other advanced manufacturing techniques, which may employ more aggressive cooling methods. This cooling method mimics the homeostasis of human body temperature, i.e., the blood circulation system, where a primary channel flows into a secondary channel with a final capillary channel that performs heat transfer very close to the body surface, and the cooling fluid is removed after the intended heat exchange. Numerous other highly effective, systematic, and individually tailored thermal regulation methods are also employed.

[0539] In temperature control systems, particularly those implemented with fluid assistance, it is important to achieve a homogeneous distribution of the temperature control fluid, close to the surface being temperature controlled. Channel applications allow for this. For some applications, a more effective temperature control is achieved with an average microchannel distance of less than 18 mm, preferably less than 8 mm, even more preferably less than 4.8 mm, and even more preferably less than 1.8 mm. For other applications, a distance that is too low can be counterproductive. In these cases, an average distance greater than 0.6 mm, or greater than 1.2 mm, or greater than 6 mm, or even more preferably greater than 16 mm, is required. Other applications require an average microchannel distance of 18 mm or less, or 9 mm or less, or 4.5 mm or less, and even more preferably less than 1.8 mm. Other applications, particularly those with high mechanical demands or where there is a risk of corrosion, require the material used to manufacture the component to have high fracture toughness. In such cases, the average diameter of the fine channels must be less than 38 mm, or less than 18 mm, or less than 8 mm, or even less than 2.8 mm. Other applications require an average equivalent diameter of the fine channels greater than 1.2 mm, or greater than 6 mm, or greater than 12 mm, or even greater than 22 mm. Some applications require a minimum average equivalent diameter of the fine channels less than 18 mm, or less than 8 mm, or even less than 2.8 mm. Other applications require an average equivalent diameter of the fine channels greater than 1.2 mm, or greater than 6 mm, or greater than 12 mm, or even greater than 22 mm. A minimum average equivalent diameter must be less than 18 mm, or less than 12 mm, or less than 9 mm, or even less than 4 mm, or less than 1.8 mm. The average equivalent diameter of the main channel must be greater than 12 mm, or greater than 22 mm, or greater than 56 mm, or greater than 108 mm.

[0540] In thermoregulation systems with primary mechanical forces driven by components, there is always a dilemma between the proximity and the channel through which the thermoregulation fluid circulates. A small channel increases the pressure drop and reduces head exchange capacity. A long distance to the thermoregulation surface results in ineffective thermoregulation. On the other hand, a large channel, located close to the thermoregulation surface, significantly increases the likelihood of mechanical failure. To resolve this dilemma, the present invention proposes a composite system that mimics the human body's blood transport (which also serves a thermoregulatory function). The human body has a large artery that carries oxygenated blood to secondary arteries and then to small capillaries. Deoxygenated blood is transported via capillaries to secondary veins and then to large veins. Similarly, as seen in Figure 1, in the proposed system, the thermoregulation fluid flows from the primary channel into secondary channels (the order of the channels can vary, and in some cases this means tertiary and quaternary channels) to regulate temperature very close to the surface, without being too small or too large. While this system may be useful in some applications, conventional cooling systems may be more effective. The smaller cross-section allows for easier control of pressure drop. Finite element simulations allow for the investigation of more advantageous configurations of secondary and primary channels for a given application, both in terms of fluid dynamics (cross-section, length, location, flow rate, pressure, fluid type, etc.) and temperature regulation effectiveness. Compared to conventional systems, the proposed system features separate channels for the inflow and outflow of temperature-regulating fluid within the same component. These channels are interconnected, and their individual cross-sections are very narrow, primarily due to the desired temperature regulation. It has been found that certain applications require the cross-section of the inflow channel (there may be two or more channels, in which case their cross-sections may be summed) to be more than three, six, 11, or even 110 times larger than the cross-section of the relatively small channel spanning the area where temperature regulation is required.

[0541] As seen in the schematic diagram of FIG. 1A, the temperature control fluid enters through a primary channel (or multiple channels; although the schematic shows one, there may be several similar primary inlet or inlet channels) and then splits into several secondary channels before reaching the microchannels where the desired heat exchange occurs. It has been found that in some implementations, this primary inlet channel is required to have several tributaries, preferably 3 or more, or 6 or more, or 22 or more, and more preferably 110 or more. As noted above, it has been found that secondary channels may have secondary channels (tertiary, quaternary, etc.), which may require a higher order of inlet channels. This number is preferably 3 or more, or 6 or more, or 12 or more. In some implementations, too many tributaries can be prohibitive. In this case, it is preferred that the order of the inlet channels be 18 or less, or 8 or less, or 4 or less, or 3 or less. In other implementations, it has been found that secondary channels are required to have multiple tributaries, preferably 3 or more, or 6 or more, or 22 or more, and more preferably 110 or more. As mentioned in the previous paragraph, heat exchange channels are often required to be close to the surface where temperature control is desired and to be spaced close to ensure uniform temperature control. Furthermore, in applications with high mechanical demands, it is desirable to have small channel cross sections to increase fluid pressure drop, but not to be too long. Figure 1B shows a schematic bird's-eye view of the distribution of secondary microchannels on the surface of a heat exchange area or working surface. In some applications, it is particularly desirable that the average length of each individual microchannel below the working surface is not excessive. (We refer to the effective length as the length of the cross section below the working surface where effective temperature control is desired. The inflow of fluid from the secondary channels, or ultimately from the main channel, into the cross section where heat exchange at the working surface is efficient is not taken into account; the average length of the ultrafine channels varies, and the arithmetic mean value is used as in the rest of this paper, unless otherwise specified.)In such cases, an average length of less than 1.8 m, or less than 450 mm, or less than 180 mm, or more preferably less than 98 mm, is required. Other applications require the use of fine cross sections or other methods to minimize pressure drop. In such cases, an average effective length of less than 240 mm, or less than 74 mm, or less than 48 mm, or more preferably less than 18 mm, is required. In other implementations, microchannels are required to behave as discontinuous channels. This, and other reasons, dictate a minimum average effective length of 12 mm or more, or greater than 32 mm, or greater than 52 mm, or even more preferably greater than 110 mm. Some applications require temperature control, which requires microchannels with a high minority surface below the working surface where this temperature control is required. Here, when a minority surface microchannel is cut at a point in the temperature-controlled region, evaluated in terms of a relatively high cross section and channel density in the presence of channels, this refers to the percentage of the total area that serves as the channel region (which in turn indicates the density of microchannels at the surface). Some applications require microchannels to be greater than 12%, or greater than 27%, or greater than 42%, and more preferably greater than 52%. Other applications require more uniform or concentrated heat exchange. In these cases, microchannel densities of 62% or greater, or greater than 72%, or greater than 77%, and more preferably greater than 86% are required. In some applications, excessive density at the surface of the microchannels can lead to mechanical failure or other problems in components. In these cases, the microchannel surface density should be 57% or less, or 47% or less, or 23% or less, and more preferably 14% or less. The ratio H, defined as the total effective length of the microchannels divided by the average effective length of the microchannels, has been found to be important when H is required to be 12 or greater, or 110 or greater, or 1100 or greater, and more preferably 11000 or greater. In other applications, excessive H values ​​are detrimental. In such cases, H should be less than 900, or less than 230, or less than 90, and more preferably less than 45.Additionally, some applications require a specific number of microchannels per square meter. In such cases, the number of microchannels per square meter is required to be 110 or more, or 1,100 or more, or 11,000 or more, or even more preferably 52,000 or more. It has also been found that some applications require a primary channel to have multiple outflow tributaries. In such cases, the primary outflow channel is required to have 3 or more, or 6 or more, or 22 or more, or even more preferably 110 or more outflow tributaries. As previously defined, it has been found that secondary channels may have secondary channels (tertiary, quaternary, etc.), and that these secondary outflow channels may require a higher order. This number is preferably 3 or more, or 6 or more, or 12 or more. In some applications, too many tributaries can be prohibitive. In this case, the order of the outflow channels is preferably 18 or less, or 8 or less, or 4 or less, or 3 or less. In other implementations, it has been found that the secondary outflow channel is required to have multiple tributaries, with this number being 3 or more, or 6 or more, or 22 or more, and more preferably 110 or more.

[0542] In some cases it may be desirable to forgo excessive branching of the channel, in which case the channel has no secondary channels, i.e. the fluid flows directly from the primary channel into the microchannel that provides thermal regulation.

[0543] For thermal conditioning applications, aqueous fluids are appropriate. In these cases, the fluid must be at least 42%, 52%, 86%, or 96% water by volume. For other applications, organic fluids primarily composed of mineral oils are also considered. These fluids must be at least 32%, 52%, 78%, or 92% mineral oil by volume. For other applications, organic fluids primarily composed of aromatic organic components are also considered. These fluids must be at least 32%, 52%, 78%, or 92% aromatic organic components by volume. For other applications, organic fluids primarily composed of vegetable oils are also considered. These fluids must be at least 32%, 52%, 78%, or 92% vegetable oil by volume. For other applications, organic fluids primarily composed of non-aromatic organic components are also considered. In this case, it is required that the total volume be at least 32%, or 52%, or 78%, or more, and more preferably 92% or more of the non-aromatic organic components. In other cases, it may be suitable for the thermal conditioning fluid to be a gas. It may be suitable for the thermal conditioning fluid to be a mist. It may be suitable for the mist or gas to enter the component at a certain pressure. In this case, an absolute inlet pressure of 2.2 bar or more, or 11 bar or more, or 110 bar or more, and more preferably 1100 bar or more is typically required. If the thermal conditioning fluid is a liquid, it is required that the absolute inlet pressure be 2.2 bar or more, or 5.5 bar or more, or 11 bar or more, and more preferably 22 bar or more.

[0544] In some applications, a rapid cooling rate of the component is desirable, such as when the component is a part or tool that cools a conforming part. This is accomplished by the present invention using conformal cooling, with near-surface channels and the system mentioned in the previous paragraph. In some applications, the present invention allows for the utilization of the latent heat of vaporization from a fluid for rapid cooling. This can be accomplished by simulating the sweating system of the human body. Metaphorically, this is referred to as a sweating element (specifically, when describing general applications for dies, molds, and tools, it is referred to as a sweating mold). This has small holes that deliver a small amount of fluid to an active evaporative surface. Some applications require a controlled dripping sequence. Other applications require a water supply of a jet or greater. Some applications require incomplete droplet formation at the active evaporative surface. Drip refers to the formation of droplets that do not shed from the evaporative surface without vaporization. To determine this sequence, control of fluid pressure, surface tension, and the geometry of the internal fluid-delivering channels and the exit holes at the active evaporative surface must be achieved. It is often suitable to implement a system with pressure drop control to balance the pressure in the different holes.

[0545] The fluid that vaporizes at the evaporation surface is often water, but an aqueous solution or suspension, or some other fluid, can be used, so this "water" can be replaced by other fluids that can vaporize with other latent heats of vaporization.

[0546] It has been found that in some applications, it is appropriate for the diameter of the tube used to deliver fluid to the active surface to be small. In such cases, it is desirable for this diameter to be less than 1.4 mm, or less than 0.9 mm, or less than 0.45 mm, and more preferably less than 0.18 mm. In some applications, it is undesirable for the diameter of the tube used to deliver fluid to the active evaporation surface to be too small. In such cases, it is desirable for this diameter to be greater than 0.08 mm, or greater than 0.6 mm, or greater than 1.2 mm, and more preferably greater than 2.2 mm. It has also been found that in some applications, the pressure applied to the fluid in the tube to transport the fluid to the active surface should not be too small. In such cases, it is desirable for there to be a pressure differential (difference from the pressure of the gas at the evaporation surface) that is less than 0.8 bar, or less than 0.4 bar, or less than 0.08 bar, and more preferably less than 0.008 bar. In some applications, it has been found useful to adjust the average number of droplets emerging from the tube holes through which fluid is delivered to the active evaporation surface. In other applications, it has been found that it is appropriate for this average number of drops not to be too high, in this case less than 80, or less than 18, or less than 4, and more preferably less than 0.8 drops per minute. As previously noted, it is desirable for droplets not to fall off at the end of the holes. In some applications, it has been found that it is appropriate for the average number of drops to emerge from the holes in the tubes through which fluid is transported to the active evaporation surface not to be too low. In such cases, it is desirable for the number of drops to emerge per minute to be greater than 80, or greater than 18, or greater than 4, and more preferably greater than 0.8. In some applications, control of the number of tubes delivering fluid to the active evaporation surface per unit of active evaporation surface is very important. In such cases, the number of cm 2More than 0.5, or more than 1.2, or more than 6, and more preferably more than 27 tubes per evaporator are required. In some applications, the percentage of the active evaporation surface that is porous is important. In such cases, the percentage of the contact surface that is porous is required to be at least greater than 1.2%, or greater than 28%, and more preferably greater than 62%. In some applications, the average distance between the centers of the holes in the active evaporation surface is required to be less than 12 times the hole diameter, or less than 8 times, or less than 4 times, and more preferably less than 1.4 times. In some applications, the surface tension of the vaporizing fluid is also important, and in these cases, it is required to be greater than 22 mM / m, or greater than 52 mM / m, or greater than 70 mM / m, and more preferably greater than 82 mM / m. Other applications require that the surface tension of the vaporizing fluid not be excessive, in this case less than 75 mm / m, or less than 69 mM / m, or less than 38 mM / m, and more preferably less than 18 mM / m.

[0547] In some applications, the way the evaporating fluid enters the tubes that deliver it to the active evaporative surface is important. This entry is often achieved through a network of channels within the component. These channels have different geometries and contain accumulation zones. Furthermore, as noted above, it may be useful to balance pressure drop zones with other zones. The goal of this channel configuration is to achieve the desired flow through each tube, as well as to equalize the pressure in the tube or its portion at the outlet. This technique, among others, was developed for drip irrigation systems and can be replicated for our purposes (though there are adaptations with scale, the concept will be primarily replicated here). It has been found that a pressure difference in the evaporating fluid may be required to reach the outlet tubes that lead to the active evaporative surface. In one representative group, this is required to be less than 8 bar, or less than 4 bar, or less than 1.8 bar, and even more preferably less than 0.8 bar. For tubes that do not require high pressure, less narrow tubes are often used, and in this case, the pressure difference is required to be less than 400 mbar, or less than 90 mbar, or less than 8 mbar, and more preferably less than 0.8 mbar. In a typical group of tubes, the vaporization at the surface is the same. This uniform pressure intensity is required for at least 35%, or more than 55%, or more than 85%, and more preferably more than 95% of the tubes in the above-mentioned area. In other cases, especially when pressure differences are required in different areas, the pressure difference in the vaporizing fluid when it reaches the tube for transport to the active evaporation surface is required. In this case, the difference between the high-pressure hole and the low-pressure hole is required to be more than 0.012 bar, or more than 0.12 bar, or more than 1.2 bar, and more preferably more than 6 bar.

[0548] One example of a sweating element is shown in Figure 2. These diagrams are intended to facilitate understanding of the embodiment and are not intended to be representative of its implementation. That is, they are presented as an example rather than a complete description of many other implementations. This example is not necessarily effective and was chosen solely for the purpose of general description, spreading the invention, and developing an implementation optimized for a particular application. Figure 2A shows a hypothetical or possible cross-section of a system of secondary microchannel surfaces through which a vaporized fluid is distributed, ultimately reaching an active evaporation surface where droplets form in the pores. It should be understood that outside the two-dimensional view of this figure are the tubes that transport the fluid to the active evaporation surface, creating the secondary surface. Figure 2B shows a bird's-eye view of the distribution of the tubes for outflow from a given active evaporation surface. Figure 2C shows a schematic representation of a portion of an additively manufactured mold, responsible for forming the tubes and corresponding pores that reach the active evaporation surface.

[0549] The cooling channels, outlet holes, and tubes for fluid delivery to the active evaporative surface are generally circular, although in some applications their cross-sections may have other or variable geometries, and this is true for all applications of the present invention unless otherwise specified.

[0550] A useful application for the temperature control systems described in this paper, as well as their combination with sweating dies, is hot stamping. All of the temperature control system and sweating die combinations described throughout this paper have utility in many applications other than hot stamping. Hot stamping also has applications in other applications, particularly those where cooling is performed using a cooling method that does not tolerate direct contact with water or steam.

[0551] In applications where water contact is not permitted, the tubes toward the active surface can be infiltrated with metals or high thermal conductivity alloys, such as Ag, Cu, or Al. These surface-facing tubes or channels then contribute to the heat transport of the active surface and the overall heat removal capacity of the component. In fact, this improves temperature control performance for both cooling and heating, and may be used in both heating and cooling applications. In some applications, metals or high thermal conductivity alloys exposed at least in some areas of the active surface are not suitable. In such cases, the tubes can lack holes and be finished below the active surface before being fully infiltrated, preventing the metal or high thermal conductivity alloy from reaching the surface.

[0552] In one implementation, the determination of cooling channel design, size, type, length, distance to effective surface, coolant flow rate, etc. is performed using available simulation software.

[0553] In the present invention, the distance between the effective surface of a tool, die, mold or part thereof and a channel refers to the shortest distance between any point of the surrounding channel and the effective surface.

[0554] In some implementations of the present invention, the shape of the channel does not have a constant cross section. In some implementations, the channel has a minimum shape and a maximum shape.

[0555] In the present invention, the average distance refers to the average value of the distance between the effective surface of the tool, die, mold or part thereof and the different channels surrounding the cross section (summed up and divided by the number of these distances), and the minimum average distance refers to the smallest average distance between the surrounding channels and the effective surface of the tool, die, mold or part thereof.

[0556] In some implementations, the channel is close to the working surface of the tool, die, mold or part thereof, and this distance may be less than 75 mm.

[0557] In another embodiment, the distance between the surrounding channel and the effective surface of the tool, die, mold, or portion thereof is less than 51 mm, in another embodiment less than 46 mm, in another embodiment less than 39 mm, in another embodiment less than 27 mm, in another embodiment less than 19 mm, in another embodiment less than 12 mm, in another embodiment less than 10 mm, in another embodiment less than 8 mm, in another embodiment less than 7.8 mm, in another embodiment less than 7.4 mm, in another embodiment less than 6.9 mm, in another embodiment less than 6.4 mm, in another embodiment less than 5.8 mm, in another embodiment less than 5.4 mm, in another embodiment less than 4.9 mm, in another embodiment less than 4.4 mm, in another embodiment less than 3.9 mm, and in another embodiment less than 3.4 mm.

[0558] In some implementations of the present invention, the shape of the cooling channels in the tool, die, mold or portion thereof can be selected from circular, square, rectangular, oval or semicircular.

[0559] In some implementations, the cooling channels in the tool, die, mold, or portion thereof include primary channels, secondary channels, or microchannels; in other implementations, the cooling channels are only primary channels; in other implementations, the cooling channels are only primary and secondary channels; in other implementations, the channels include all primary, secondary, and microchannels; in still other implementations, the cooling channels in the tool, die, mold, or portion thereof include only primary and microchannels; in still other implementations, the cooling channels are only secondary and microchannels; in still other implementations, the cooling channels are only secondary channels; and in still other implementations, only microchannels.

[0560] In one embodiment, the primary channel in a tool, die, mold, or portion thereof is 2041.8 mm for a given cross section of the primary channel. 2 In another embodiment, the area has a shape less than 1661.1 mm 2 In another implementation, 1194 mm 2 In another experiment, 572.3 mm 2 In another experiment, 283.4 mm 2 In another implementation, 213.0 mm 2In another implementation, 149 mm 2 In another implementation, 108 mm 2 In another implementation, 42 mm 2 In another implementation, 37 mm 2 In another implementation, 31 mm 2 In another implementation, 28 mm 2 In another implementation, 21 mm 2 In another implementation, 14 mm 2 less than 56mm in other implementations 2 from 21mm 2 while in yet another implementation 56 mm 2 from 14mm 2 The area has a shape ranging between .

[0561] In some implementations, when the cross section is not constant, the shape of the primary channel in the tool, die, mold, or portion thereof refers to the smallest shape of the channel.

[0562] Also, in some implementations, the secondary channel in the tool, die, mold, or portion thereof may be 122.3 mm 2 In another embodiment, the area has a shape less than 82.1 mm 2 Less than, and in another implementation, 68.4 mm 2 Less than, and in another implementation, 43.1 mm 2 Less than, and in another implementation, 26.4 mm 2 Less than, and in another implementation, 23.2 mm 2 less than, and in another implementation, 18.3 mm 2 less than, and in another implementation, 14.1 mm 2 less than, and in another implementation, 11.2 mm 2 less than, and in another implementation, 9.3 mm 2 less than, and in another implementation, 7.2 mm 2 less than, and in another implementation, 6.4 mm 2 less than, and in another implementation, 5.8 mm 2 less than, and in another implementation, 5.2 mm 2 less than, and in another implementation, 4.8 mm2 less than, and in another implementation, 4.2 mm 2 less than, and in another implementation, 3.8 mm 2 less than 7.8 mm in other implementations 2 from 3.8 mm 2 and in yet another implementation, 5.2 mm 2 from 3.8 mm 2 The area has a shape ranging between .

[0563] In some implementations, when the cross section is not constant, the shape of a secondary channel in the tool, die, mold, or portion thereof refers to the smallest shape of that channel.

[0564] Also, in some implementations, the microchannels in the tool, die, mold, or portion thereof may be 1.6 mm or less at a given cross section of the microchannel. 2 In another embodiment, the area has a shape less than 1.2 mm. 2 less than, and in another implementation, 0.8 mm 2 less than 0.45 mm in other implementations 2 less than 0.18 mm in other implementations 2 In other embodiments, the microchannels in the tool, die, mold, or portion thereof have areas with features that are less than 1.6 mm in size. 2 to 0.18 mm 2 and in yet another implementation 1.6 mm 2 from 0.45 mm 2 while in another experiment it was 1.2 mm 2 from 0.45 mm 2 The area has a shape ranging between .

[0565] In some implementations, when the cross section is not constant, the shape of a microchannel in the tool, die, mold, or portion thereof refers to the smallest shape of the channel.

[0566] In the present invention, equivalent diameter refers to the diameter of a sphere equivalent to square, rectangular, elliptical and other shapes, including more complex shapes such as semicircular.

[0567] In some implementations, for secondary channel shapes including circular, as well as squa...

Claims

1. A steel having the following composition: 【Chemistry 1】 where all percentages are by weight The balance consists of iron and trace elements, %Ceq=%C+0.86×%N+1.2×%B; %Al+%Si+%Cr+%V>2%; Steels where %Al<10% when %C>0.9%.

2. 2. The steel according to claim 1, wherein %Ni is between 0.1% and 8%.

3. 3. The steel according to claim 1 or 2, wherein %Cr is at least 0.1%.

4. 4. The steel according to any one of claims 1 to 3, wherein %Cr + %Ni is higher than 0.1%.

5. 5. A steel according to any one of claims 1 to 4, wherein %Cr + %Cu + %Si is greater than 0.1%.

6. 6. A steel according to any one of the preceding claims, wherein %Mo is between 0.01% and 7.6%.

7. 7. A steel according to any one of the preceding claims, wherein %C is lower than 1.93%.

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