Low-alloy wear-resistant steel and preparation method thereof

Abstract

The invention discloses low-alloy wear-resistant steel and a preparation method thereof. The invention relates to low-alloy wear-resistant steel, which is prepared from the following chemical components in percentage by weight: 0.14 to 0.30 weight percent of C, 0.3 to 1.5 weight percent of Si, 1.0 to 2.5 weight percent of Mn, 0.10 to 0.50 weight percent of Cr, 0.05 to 0.35 weight percent of Mo, 0.01 to 0.08 weight percent of Nb, 0 to 0.050 weight percent of Ti, 0.030 to 0.080 weight percent of Al, 0.01 to 0.06 weight percent of M, less than or equal to 0.005 weight percent of P, less than or equal to 0.005 weight percent of S, 0.0010 to 0.0030 weight percent of B, less than or equal to 0.0030 weight percent of O, less than or equal to 0.0060 weight percent of N and the balance of iron and inevitable trace elements, wherein M comprises a rare earth element, and the rare earth element comprises one or more of Ce and La. According to the embodiment of the invention, good wear resistance and bending performance are achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of wear-resistant steel, and in particular, relates to a low-alloy wear-resistant steel and a preparation method thereof. Background Art

[0002] Low alloy wear-resistant steel is widely used in engineering, mining, agriculture, ports, electric power and other mechanical products, such as bulldozers, excavators, dump trucks, etc.

[0003] However, the harsh service environment often causes the steel to break and wear out. And with the complexity of engineering components, this type of steel is also required to have excellent bending and processing properties. Summary of the invention

[0004] The embodiment of the present application provides a low-alloy wear-resistant steel and a preparation method thereof, which has good wear resistance and bending performance.

[0005] In a first aspect, an embodiment of the present application provides a low alloy wear-resistant steel, wherein the chemical composition of the low alloy wear-resistant steel comprises, by weight percentage: C: 0.14wt% to 0.30wt%, Si: 0.3wt% to 1.5wt%, Mn: 1.0wt% to 2.5wt%, Cr: 0.10wt% to 0.50wt%, Mo: 0.05wt% to 0.35wt%, Nb: 0.01wt% to 0.08wt%, Ti: 0.0 .050wt%, Al: 0.030wt%~0.080wt%, M: 0.01wt%~0.06wt%, P≤0.005wt%, S≤0.005wt%, B: 0.0010wt%~0.0030wt%, O≤0.0030wt%, N≤0.0060wt%, and the rest are iron and inevitable trace elements; wherein M includes rare earth elements, and the rare earth elements include one or more of Ce and La.

[0006] In any embodiment of the present application, the chemical composition of the low alloy wear-resistant steel includes, by weight percentage: C: 0.15wt% ~ 0.25wt%, Si: 0.3wt% ~ 1.2wt%, Mn: 1.0wt% ~ 2.0wt%, Cr: 0.10wt% ~ 0.50wt%, Mo: 0.05wt% ~ 0.35wt%, Nb: 0.01wt% ~ 0.08wt%, Ti: 0 ~ 0.050wt%, Al: 0.030wt% ~ 0.080wt%, M: 0.01wt% ~ 0.04wt%, P ≤ 0.005wt%, S ≤ 0.005wt%, B: 0.0010wt% ~ 0.0030wt%, O ≤ 0.0030wt%, N ≤ 0.0060wt%, and the rest are iron and inevitable trace elements; wherein M includes rare earth elements, and the rare earth elements include one or more of Ce and La.

[0007] In any embodiment of the present application, the metallographic structure of the low alloy wear-resistant steel includes austenite and tempered martensite.

[0008] In any embodiment of the present application, based on the low alloy wear-resistant steel, the content of austenite accounts for 5% to 10%.

[0009] In any embodiment of the present application, the {112} <111> The α texture content accounts for 0.

[0010] In any embodiment of the present application, the inclusions in the low alloy wear-resistant steel include spherical inclusions.

[0011] In any embodiment of the present application, the level of inclusions in the low alloy wear-resistant steel is less than level 1.5 and the size is less than 2 microns.

[0012] In any embodiment of the present application, the Brinell hardness of the low alloy wear-resistant steel is 430-470 HB, the yield strength is greater than 1100 MPa, and the elongation is ≥12.0%.

[0013] In a second aspect, an embodiment of the present application provides a method for preparing a low alloy wear-resistant steel, comprising: casting a molten steel containing a preset element ratio to obtain a cast billet; rolling the cast billet under preset conditions and performing an offline heat treatment to obtain a low alloy wear-resistant steel; the chemical composition of the low alloy wear-resistant steel comprises, by weight percentage: C: 0.14wt% to 0.30wt%, Si: 0.3wt% to 1.5wt%, Mn: 1.0wt% to 2.5wt%, Cr: 0.10wt% to 0.50wt%, Mo: 0.05wt% to 0.10wt%; .35wt%, Nb: 0.01wt%~0.08wt%, Ti: 0~0.050wt%, Al: 0.030wt%~0.080wt%, M: 0.01wt%~0.06wt%, P≤0.005wt%, S≤0.005wt%, B: 0.0010wt%~0.0030wt%, O≤0.0030wt%, N≤0.0060wt%, and the rest are iron and inevitable trace elements; wherein M includes rare earth elements, and the rare earth elements include one or more of Ce and La.

[0014] In any embodiment of the present application, the temperature of the casting process is 1500-1550°C.

[0015] In any embodiment of the present application, rolling the ingot under preset conditions includes: performing a first rolling on the ingot at a first temperature, performing a second rolling on the ingot at a second temperature, cooling the ingot to a third temperature at a first cooling rate, and then cooling the ingot to a fourth temperature at a second cooling rate.

[0016] In any embodiment of the present application, the first temperature is 980-1120°C, the reduction rate of the first rolling is 70%-85%, the second temperature is 860-930°C, the reduction rate of the second rolling is 60%-90%, the third temperature is 400-500°C, the fourth temperature is 20-30°C, the first cooling rate is 320-420°C / s, and the second cooling rate is 200-300°C / s.

[0017] In any embodiment of the present application, the casting is further subjected to heating treatment before rolling, the heating temperature is 1180-1250° C., and the holding time is 120-180 min.

[0018] In any embodiment of the present application, the offline heat treatment includes quenching and tempering the ingot; the holding temperature of the quenching treatment is 880-930°C, the holding time is 20-40min, and the cooling rate is 300-500°C / s; the holding temperature of the tempering treatment is 190-230°C, the holding time is 15-45min, and the cooling rate is 300-500°C / s.

[0019] The low-alloy wear-resistant steel and preparation method thereof of the embodiments of the present application can adjust the elemental composition of the low-alloy wear-resistant steel so that the metallographic structure of the low-alloy wear-resistant steel has a specific content of tempered martensite and austenite. The specific ratio of tempered martensite and austenite can interact with each other to improve the hardness and toughness of the wear-resistant steel, thereby making the wear-resistant steel have good wear resistance and bending performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0021] Figure 1 This is a microstructure diagram of the martensite structure after heat treatment in Example 1 of the present application.

[0022] Figure 2 This is the microstructure diagram of inclusions in the low alloy wear-resistant steel of Example 1 of the present application.

[0023] Figure 3 This is the ODF diagram of texture distribution in low alloy wear-resistant steel in Example 1 of the present application.

[0024] Figure 4 This is a real photo of the low-alloy wear-resistant steel in Example 1 of the present application in a bent state. DETAILED DESCRIPTION

[0025] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the scheme of the present application will be further described below. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present application may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present application, rather than all of the embodiments.

[0027] Hereinafter, the low alloy wear-resistant steel and the method for preparing the same of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0028] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] If not otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0030] Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0031] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0032] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0033] Unless otherwise specified, this application adopts conventional test methods or test methods recommended by the instrument.

[0034] Low alloy wear resistant steel

[0035] An embodiment of the present application provides a low-alloy wear-resistant steel. The chemical composition of the low-alloy wear-resistant steel includes, by weight percentage: C: 0.14wt%~0.30wt%, Si: 0.3wt%~1.5wt%, Mn: 1.0wt%~2.5wt%, Cr: 0.10wt%~0.50wt%, Mo: 0.05wt%~0.35wt%, Nb: 0.01wt%~0.08wt%, Ti: 0~0.050wt%, Al: 0.030wt%~0.080wt%, M: 0.01wt%~0.06wt%, P≤0.005wt%, S≤0.005wt%, B: 0.0010wt%~0.0030wt%, O≤0.0030wt%, N≤0.0060wt%, and the rest are iron and inevitable trace elements; wherein M includes rare earth elements, and the rare earth elements include one or more of Ce and La.

[0036] In the related art, the carbon concentration and alloy content are high, and a martensitic low alloy wear-resistant steel is obtained. The wear-resistant steel has high strength and hardness, and thus has excellent wear resistance. However, the toughness and bending forming performance of the wear-resistant steel are reduced.

[0037] The elemental composition of the low alloy wear-resistant steel in the embodiment of the present application can be affected by the phase transition temperature to obtain tempered martensite and austenite with a specific content ratio. The tempered martensite is harder, has very high hardness and strength, and also has good toughness and ductility; the austenite has a face-centered cubic (fcc) structure, which makes its octahedral gap larger and can accommodate more carbon atoms, so that it can have good plasticity and toughness. Thereby, the wear resistance and bending performance of the low alloy wear-resistant steel are improved. And the bending angle of the low alloy wear-resistant steel is 90°, and the steel plate does not crack when the bending diameter d=4a. At the same time, the elemental composition of the low alloy wear-resistant steel can also reduce {112} <111> The α texture and the content of impurity elements can also regulate the morphology and level of inclusions, thereby further improving the wear resistance and bending properties of low alloy wear-resistant steel.

[0038] Carbon (C): C affects the strength and welding performance of steel. C mainly plays a role in solid solution strengthening. C interacts with carbide-forming elements such as Nb and Ti to form carbides, which plays a role in precipitation strengthening. In order to ensure the lath martensite in low-alloy wear-resistant steel, the C content is generally designed not to exceed 0.30wt%, so as to ensure that the wear-resistant steel has high strength and certain plasticity and toughness. In addition, too high a C content will reduce the welding performance of the steel.

[0039] Silicon (Si): Si is an important reducing agent and deoxidizing agent. Si within this range dissolves in ferrite and austenite and can play a role in solid solution strengthening.

[0040] Manganese (Mn): Mn and Fe can form an infinite solid solution, which has a solid solution strengthening effect and increases the hardenability of steel. However, Mn is easy to form inclusions MnS with S, which is not good for toughness. Mn within this range can improve the hardenability of steel while improving the toughness of steel.

[0041] Chromium (Cr): Cr can increase the hardenability of steel. Cr within this range can make the steel have better comprehensive mechanical properties after quenching and tempering.

[0042] Molybdenum (Mo): Mo within this range can improve the hardenability and tempering stability of steel and reduce temper brittleness.

[0043] Niobium (Nb): Nb is a strong carbide-forming element. Nb within this range can cause the undissolved NbCN in the hot rolling stage to hinder the migration of austenite grain boundaries to refine the grains, and can also cause nano-sized NbCN to precipitate during the cooling process of austenite to strengthen the austenite.

[0044] Titanium (Ti): Ti has a strong affinity with N, O, and C, and a stronger affinity with S than Fe, making it a good deoxidizer and degasser. Ti within this range can make the undissolved TiCN in the hot rolling stage hinder the migration of austenite grain boundaries to refine the grains, and can also make nano-sized TiCN precipitate during the cooling process of austenite to strengthen the effect.

[0045] Boron (B): B within this range can increase the hardenability of steel and can reduce the addition amounts of Ni, Cr and Mo, thereby reducing costs.

[0046] Aluminum (Al): Al is a deoxidizer in steel. Within this range, Al can combine with N to form AlN to refine the grains, while also reducing the adverse effects of Al on the hot working properties, welding properties and cutting properties of steel.

[0047] Cerium (Ce) / Lanthanum (La): Rare earth elements Ce / La within this range can reduce the segregation of C, P, Mn, and Si between columnar crystals and equiaxed crystals in the continuous casting billet by affecting the solidification process and solidification structure, expand the equiaxed crystal area, and refine the grains. At the same time, rare earth elements Ce / La have strong deoxidation and desulfurization effects. Rare earth elements Ce / La within this range can reduce the segregation of S and P at the grain boundaries, change the morphology of sulfide inclusions, and thus reduce the impact of inclusions on the performance of wear-resistant steel.

[0048] Sulfur (S): S exists in steel in the form of FeS. At high temperatures, FeS forms low-melting-point compounds with Fe, which are prone to hot brittleness during hot rolling of steel. S combines with Mn to form MnS inclusions, which are detrimental to the plasticity and toughness of steel. S within this range can reduce the degree of deterioration of the hot brittleness of steel caused by low-melting-point compounds, and can also reduce the degree of deterioration of the plasticity and toughness of steel caused by MnS inclusions.

[0049] Phosphorus (P): P plays a role in solid solution strengthening in steel, increasing the strength and hardness of steel, but P tends to segregate at the grain boundaries, which will reduce the plasticity and impact toughness of steel. S within this range can improve the strength and hardness of steel, while also reducing the plasticity and impact toughness of steel.

[0050] Oxygen (O): O is a harmful element in steel, mainly existing in the form of inclusions such as SiO2 and Al2O3. O in this range can reduce the deterioration of steel strength and plasticity caused by inclusions such as SiO2 and Al2O3, especially the deterioration of fatigue performance and impact toughness.

[0051] Nitrogen (N): N within this range can improve the strength of steel and reduce the deterioration of welding performance and cold bending performance.

[0052] In some embodiments, in order to better improve the wear resistance and bending performance of low alloy wear-resistant steel, the chemical composition of low alloy wear-resistant steel includes, by weight percentage: C: 0.15wt% ~ 0.25wt%, Si: 0.3wt% ~ 1.2wt%, Mn: 1.0wt% ~ 2.0wt%, Cr: 0.10wt% ~ 0.50wt%, Mo: 0.05wt% ~ 0.35wt%, Nb: 0.01wt% ~ 0.08wt%, Ti :0~0.050wt%, Al:0.030wt%~0.080wt%, M:0.01wt%~0.04wt%, P≤0.005wt%, S≤0.005wt%, B:0.0010wt%~0.0030wt%, O≤0.0030wt%, N≤0.0060wt%, and the rest are iron and inevitable trace elements; wherein M includes rare earth elements, and the rare earth elements include one or more of Ce and La.

[0053] The wear-resistant steel in the related art has a metallographic structure of ferrite, ferrite plus martensite and tempered martensite from the surface to the core of the steel. When the steel plate is bent at 90°, the bending diameter d=na, n is 2-4, and the bending performance is good. However, the surface is ferrite, which is not conducive to the wear resistance of the steel plate.

[0054] In some embodiments, the metallographic structure of the low alloy wear resistant steel includes austenite and tempered martensite.

[0055] Austenite has a face-centered cubic (fcc) structure and is an interstitial solid solution of carbon dissolved in γ-Fe, also known as austenite or γ-Fe. It is usually a non-magnetic solid solution formed by a small amount of carbon dissolved in γ-Fe. Austenite has good plasticity, low strength, certain toughness, and is not ferromagnetic.

[0056] Tempered martensite is formed by low-temperature tempering of quenched martensite. The lamellar martensite (body-centered tetragonal crystal structure) formed during quenching decomposes in the first stage of tempering, and the carbon therein is precipitated in the form of transition carbides. The resulting complex structure of extremely fine transition carbide flakes (the interface with the matrix is ​​a coherent interface) dispersed in the solid solution matrix (the crystal structure has become body-centered cubic) is tempered martensite. Tempered martensite has high hardness and strength as well as good toughness and ductility, and thus has good wear resistance and bending resistance.

[0057] The low-alloy wear-resistant steel with a suitable metallographic structure in the embodiment of the present application can have good wear resistance and bending resistance under the interaction of austenite and tempered martensite.

[0058] In some embodiments, in order to better improve the wear resistance and bending resistance of the low alloy wear-resistant steel, based on the low alloy wear-resistant steel, the content of austenite accounts for 5% to 10%.

[0059] The embodiment of the present application has a suitable content of austenite, and austenite has good bulk plasticity, so that the wear-resistant steel can have good wear resistance; at the same time, austenite is relatively soft and is generally distributed at the boundaries of martensite laths, which can relieve stress concentration during the bending or deformation of the steel, thereby improving the bending rate and elongation of the wear-resistant steel.

[0060] Optionally, the content of austenite is independently selected from any value of 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, or any range therebetween.

[0061] In some embodiments, the {112} <111> The α texture content accounts for 0.

[0062] In their natural state, the orientation of grains in a material is usually random. However, under the influence of certain processing techniques or external conditions, the grains may tend to have a specific orientation, a phenomenon called texture. {112} <111> α texture refers to a specific crystal plane ({112}) and crystal direction ( <111> ) presents an orderly arrangement in the material. Among them, {112} represents the crystal plane, <111> Compared with other wear-resistant steels, the low-alloy wear-resistant steel in the embodiment of the present application can suppress {112} under a specific element ratio and a special quenching process. <111> The formation of α texture reduces the {112} <111> The α texture deteriorates the bending performance of the steel plate, thereby improving the bending performance of the low alloy wear-resistant steel.

[0063] In some embodiments, the inclusions in the low alloy wear resistant steel include spherical inclusions.

[0064] In some embodiments, the inclusions in the low alloy wear resistant steel have a grade less than 1.5 and a size less than 2 microns.

[0065] In the wear-resistant steel of the related art, there are triangular calcium-magnesium-aluminum inclusions. The corners in the triangular morphology of the inclusions are easy to become the starting point of cracks, causing the steel to break easily when subjected to stress, thereby reducing its strength and toughness. The low-alloy wear-resistant steel of the embodiment of the present application can transform the inclusions into spherical inclusions and reduce their particle size by introducing a specific content of rare earth elements. Inclusions with this morphology and level have no stress concentration, and the steel is not easy to break when subjected to stress, thereby improving the strength and toughness of the steel.

[0066] In some embodiments, the low alloy wear-resistant steel has a Brinell hardness of 430-470 HB, a yield strength greater than 1100 MPa, and an elongation of ≥12.0%.

[0067] Optionally, the Brinell hardness of the low alloy wear-resistant steel is independently selected from any value among 430HB, 440HB, 450HB, 460HB, 470HB, or a range of values ​​between any two of them.

[0068] Optionally, the yield strength of the low alloy wear-resistant steel is independently selected from any value of 1100 MPa, 1110 MPa, 1120 MPa, 1130 MPa, 1140 MPa, 1150 MPa, 1160 MPa, 1170 MPa, 1180 MPa, 1190 MPa, 1200 MPa, 1210 MPa, 1220 MPa, 1230 MPa, 1240 MPa, 1250 MPa, or a range value between any two of them.

[0069] Optionally, the elongation of the low alloy wear resistant steel is independently selected from any value among 12.0%, 12.1%, 12.2%, 12.3%, 12.4%, 12.5%, 12.6%, 12.7%, 12.8%, 12.9%, 13.0%, 13.1%, 13.2%, 13.3%, 13.4%, 13.5%, 13.6%, 13.7%, 13.8%, 13.9%, 14.0%, or any range value therebetween.

[0070] Preparation method of low alloy wear-resistant steel

[0071] The present application provides a method for preparing low-alloy wear-resistant steel, comprising: S1, casting molten steel containing a preset element ratio to obtain a cast billet; S2, rolling the cast billet under preset conditions and performing an offline heat treatment to obtain a low-alloy wear-resistant steel; in terms of weight percentage, the chemical composition of the low-alloy wear-resistant steel comprises: C: 0.14wt% to 0.30wt%, Si: 0.3wt% to 1.5wt%, Mn: 1.0wt% to 2.5wt%, Cr: 0.10wt% to 0.50wt%, Mo: 0.05wt% to 0.1wt% .35wt%, Nb: 0.01wt%~0.08wt%, Ti: 0~0.050wt%, Al: 0.030wt%~0.080wt%, M: 0.01wt%~0.06wt%, P≤0.005wt%, S≤0.005wt%, B: 0.0010wt%~0.0030wt%, O≤0.0030wt%, N≤0.0060wt%, and the rest are iron and inevitable trace elements; wherein M includes rare earth elements, and the rare earth elements include one or more of Ce and La.

[0072] In the embodiment of the present application, molten steel containing a preset element ratio is rolled and heat treated under specific parameters to obtain tempered martensite and part of austenite, thereby reducing {112} <111> The content of α texture is reduced, and the inclusion level is less than 1.5, the inclusions are spherical, and the size is less than 2 microns. Thus, the wear-resistant steel with a hardness between 430 and 470 HB and no cracking when the bending angle is 90° and the bending diameter is d=4a is obtained.

[0073] In some embodiments, step S1 includes subjecting the molten steel to RH (vacuum cycle degassing) treatment and LF-VD (ladle refining furnace-vacuum degassing) treatment before casting to remove impurities and gases in the molten steel. In step S1, those skilled in the art can adjust the element ratio of the molten steel according to the element composition of the target wear-resistant steel.

[0074] In some embodiments, the temperature of the casting process is 1500-1550°C.

[0075] Optionally, the temperature of the casting process is independently selected from any value of 1500° C., 1510° C., 1520° C., 1530° C., 1540° C., 1550° C., or any range therebetween.

[0076] In some embodiments, rolling the ingot under preset conditions includes: performing a first rolling on the ingot at a first temperature, performing a second rolling on the ingot at a second temperature, cooling the ingot to a third temperature at a first cooling rate, and finally cooling the ingot to a fourth temperature at a second cooling rate.

[0077] In some embodiments, the first temperature is 980-1120°C, the reduction rate of the first rolling is 70%-85%, the second temperature is 860-930°C, the reduction rate of the second rolling is 60%-90%, the third temperature is 400-500°C, the fourth temperature is 20-30°C, the first cooling rate is 320-420°C / s, and the second cooling rate is 200-300°C / s.

[0078] Optionally, the first temperature is independently selected from any value of 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C, 1090°C, 1100°C, 1110°C, 1120°C, or any range therebetween.

[0079] Optionally, the second temperature is independently selected from any value of 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, or any range therebetween.

[0080] Optionally, the third temperature is independently selected from any value of 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, or any range therebetween.

[0081] Optionally, the fourth temperature is independently selected from any value of 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, or a range therebetween.

[0082] In some embodiments, the casting is further subjected to heating treatment before rolling, the heating temperature is 1180-1250° C., and the holding time is 120-180 min.

[0083] Optionally, the heating temperature is independently selected from any value of 1180°C, 1190°C, 1200°C, 1210°C, 1220°C, 1230°C, 1240°C, 1250°C, or any range therebetween.

[0084] Optionally, the holding time is independently selected from any value among 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min, or any range value between two of them.

[0085] In some embodiments, the offline heat treatment includes quenching and tempering the ingot; the holding temperature of the quenching treatment is 880-930°C, the holding time is 20-40 min, and the cooling rate is 300-500°C / s; the holding temperature of the tempering treatment is 190-230°C, the holding time is 15-45 min, and the cooling rate is 300-500°C / s.

[0086] In the embodiment of the present application, when the quenching treatment is performed, the pearlite can be completely converted into austenite by adjusting the holding temperature and the holding temperature to perform austenitization, and at the same time, the {112} <111> Then, by adjusting the cooling rate to room temperature (20-30°C), most of the austenite is converted into martensite, and a specific content of austenite is retained. Then, tempering treatment is performed at 190-230°C to convert the martensite into tempered martensite, thereby obtaining a special ratio of tempered martensite and austenite.

[0087] Optionally, the holding temperature of the quenching treatment is independently selected from any value of 880° C., 890° C., 900° C., 910° C., 920° C., 930° C., or any range therebetween.

[0088] Optionally, the holding time of the quenching treatment is independently selected from any value among 20 min, 25 min, 30 min, 35 min, 40 min, or any range value therebetween.

[0089] Optionally, the cooling rate after quenching treatment is independently selected from any value of 300°C / s, 350°C / s, 400°C / s, 450°C / s, 500°C / s, or any range between two values.

[0090] Optionally, the holding temperature of the tempering treatment is independently selected from any value of 190° C., 200° C., 210° C., 220° C., 230° C., or any range therebetween.

[0091] Optionally, the holding time of the tempering treatment is independently selected from any value of 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, or any range value therebetween.

[0092] Optionally, the cooling rate after the tempering treatment is independently selected from any value of 300°C / s, 350°C / s, 400°C / s, 450°C / s, 500°C / s, or any range between two values.

[0093] Example

[0094] The chemical compositions of the examples are shown in Table 1.

[0095]

[0096] Example 1

[0097] According to the chemical composition of Example 1 in Table 1, the steel was smelted, RH and LF-VD were treated, the molten steel was cast into ingots, and the ingots were subjected to controlled rolling. The rough rolling temperature was 1150°C, the pass reduction rate was 15%, the finishing rolling temperature was 910°C, the pass reduction rate was 40%, the steel plate thickness was greater than 5 mm, and after finishing rolling, the laminar cooling was to 500°C, and then air cooling was to 25°C.

[0098] The rolled steel plate is subjected to offline heat treatment, kept at 900°C for 30 minutes for austenitization, then cooled to room temperature at 350°C / s, the austenite is basically converted into martensite, then kept at 200°C for 25 minutes for tempering martensite, and finally cooled to room temperature at 300°C / s to obtain low alloy wear-resistant steel.

[0099] Example 2

[0100] According to the chemical composition of Example 2 in Table 1, the steel was smelted, RH and LF-VD treated, the molten steel was cast into ingots, and the ingots were subjected to controlled rolling. The rough rolling temperature was 1160°C, the pass reduction rate was 20%, the finishing rolling temperature was 900°C, the pass reduction rate was 45%, the steel plate thickness was greater than 5 mm, and after finishing rolling, the laminar cooling was to about 480°C, and then air cooling was to 25°C.

[0101] The rolled steel plate is subjected to offline heat treatment, kept at 910°C for 20 minutes for austenitization, then cooled to room temperature at 360°C / s, the austenite is basically converted into martensite, then kept at 190°C for 30 minutes for tempering martensite, and finally cooled to room temperature at 300°C / s to obtain low alloy wear-resistant steel.

[0102] Example 3

[0103] According to the chemical composition of Example 3 in Table 1, the test steel was smelted, RH and LF-VD were treated, the molten steel was cast into ingots, and the ingots were subjected to controlled rolling. Among them, the rough rolling temperature was 1150°C, the pass reduction rate was 15%, the finishing rolling temperature was 890°C, the pass reduction rate was 45%, the steel plate thickness was greater than 5 mm, and after finishing rolling, the laminar cooling was performed to about 480°C, and then air cooling was performed to 20°C.

[0104] The rolled steel plate is subjected to offline heat treatment, the rolled steel plate is subjected to offline heat treatment, kept at 900°C for 30 minutes for austenitization, then cooled to room temperature at 340°C / s, the austenite is basically converted into martensite, then kept at 200°C for 40 minutes for tempering martensite, and finally cooled to room temperature at 350°C / s to obtain low alloy wear-resistant steel.

[0105] Example 4

[0106] According to the chemical composition of Example 4 in Table 1, the test steel was smelted, RH and LF-VD were treated, the molten steel was cast into ingots, and the ingots were subjected to controlled rolling. Among them, the rough rolling temperature was 1140°C, the pass reduction rate was 20%, the finishing rolling temperature was 890°C, the pass reduction rate was 40%, the steel plate thickness was greater than 5 mm, and after finishing rolling, the laminar flow was cooled to about 450°C, and then air-cooled to 20°C.

[0107] The rolled steel plate is subjected to offline heat treatment, and is kept at 890°C for 30 minutes for austenitization, and then cooled to room temperature at 450°C / s, the austenite is basically converted into martensite, and then kept at 210°C for 45 minutes for tempering martensite, and finally cooled to room temperature at 320°C / s to obtain low alloy wear-resistant steel.

[0108] Example 5

[0109] According to the chemical composition of Example 5 in Table 1, the test steel was smelted, RH and LF-VD were treated, the molten steel was cast into ingots, and the ingots were subjected to controlled rolling. Among them, the rough rolling temperature was 1150°C, the pass reduction rate was 15%, the finishing rolling temperature was 880°C, the pass reduction rate was 45%, the steel plate thickness was greater than 5 mm, and after finishing rolling, the laminar cooling was performed to about 470°C, and then air cooling was performed to 25°C.

[0110] The rolled steel plate is subjected to offline heat treatment, and is kept at 910°C for 25 minutes for austenitization, and then cooled to room temperature at 360°C / s, the austenite is basically converted into martensite, and then kept at 200°C for 30 minutes for tempering martensite, and finally cooled to room temperature at 340°C / s to obtain low alloy wear-resistant steel.

[0111] Example 6

[0112] The experimental steps are basically the same as those in Example 1, except that the austenitizing holding temperature is changed to 1050° C. and the holding time is changed to 60 min.

[0113] Example 7

[0114] The experimental steps are basically the same as those in Example 1, except that the cooling rate after austenitization is changed to 660°C / s.

[0115] The steel plates of Examples 1-7 were subjected to microstructure analysis and room temperature tensile test for mechanical properties, according to the standard GB / T228.1-2010, and the hardness test was measured according to the method of GB / T231.1-2009. The results are shown in Table 2:

[0116]

[0117] The above is only a specific implementation of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the protection scope of this application.

Claims

1. A low alloy wear-resistant steel, characterized in that: The chemical composition of the low alloy wear-resistant steel includes, by weight percentage: C: 0.14wt%~0.30wt%, Si: 0.3wt%~1.5wt%, Mn: 1.0wt%~2.5wt%, Cr: 0.10wt%~0.50wt%, Mo: 0.05wt%~0.35wt%, Nb: 0.01wt%~0.08wt%, Ti: 0~0.050wt%, Al: 0.030wt%~0.080wt%, M: 0.01wt%~0.06wt%, P≤0.005wt%, S≤0.005wt%, B: 0.0010wt%~0.0030wt%, O≤0.0030wt%, N≤0.0060wt%, the rest are iron and inevitable trace elements; Wherein, M includes rare earth elements, and the rare earth elements include one or more of Ce and La.

2. The low alloy wear-resistant steel according to claim 1, characterized in that: The chemical composition of the low alloy wear-resistant steel includes, by weight percentage: C: 0.15wt%~0.25wt%, Si: 0.3wt%~1.2wt%, Mn: 1.0wt%~2.0wt%, Cr: 0.10wt%~0.50wt%, Mo: 0.05wt%~0.35wt%, Nb: 0.01wt%~0.08wt%, Ti: 0~0.050wt%, Al: 0.030wt%~0.080wt%, M: 0.01wt%~0.04wt%, P≤0.005wt%, S≤0.005wt%, B: 0.0010wt%~0.0030wt%, O≤0.0030wt%, N≤0.0060wt%, the rest are iron and inevitable trace elements; Wherein, M includes rare earth elements, and the rare earth elements include one or more of Ce and La.

3. The low alloy wear-resistant steel according to claim 1, characterized in that: The metallographic structure of the low alloy wear-resistant steel includes austenite and tempered martensite; and / or, Based on the low alloy wear-resistant steel, the content of austenite accounts for 5% to 10%.

4. The low alloy wear-resistant steel according to claim 1, characterized in that: The {112} <111> The alpha texture content is 0; and / or, The inclusions in the low alloy wear-resistant steel include spherical inclusions; and / or, The level of inclusions in the low alloy wear-resistant steel is less than level 1.5, and the size is less than 2 microns.

5. The low alloy wear-resistant steel according to claim 1, characterized in that: The low alloy wear-resistant steel has a Brinell hardness of 430-470 HB, a yield strength greater than 1100 MPa, and an elongation of ≥12.0%.

6. A method for preparing low alloy wear-resistant steel, characterized in that: include: Casting molten steel containing a preset element ratio to obtain a casting billet; The ingot is subjected to rolling treatment and offline heat treatment under preset conditions to obtain low alloy wear-resistant steel; The chemical composition of the low alloy wear-resistant steel includes, by weight percentage: C: 0.14wt%~0.30wt%, Si: 0.3wt%~1.5wt%, Mn: 1.0wt%~2.5wt%, Cr: 0.10wt%~0.50wt%, Mo: 0.05wt%~0.35wt%, Nb: 0.01wt%~0.08wt%, Ti: 0~0.050wt%, Al: 0.030wt%~0.080wt%, M: 0.01wt%~0.06wt%, P≤0.005wt%, S≤0.005wt%, B: 0.0010wt%~0.0030wt%, O≤0.0030wt%, N≤0.0060wt%, the rest are iron and inevitable trace elements; Wherein, M includes rare earth elements, and the rare earth elements include one or more of Ce and La.

7. The preparation method according to claim 6, characterized in that: The temperature of the casting process is 1500-1550°C.

8. The preparation method according to claim 6, characterized in that: The rolling process of the cast billet under preset conditions comprises: The ingot is subjected to a first rolling at a first temperature, a second rolling at a second temperature, cooled to a third temperature at a first cooling rate, and then cooled to a fourth temperature at a second cooling rate; and / or, The first temperature is 980-1120°C, the first rolling reduction rate is 70%-85%, the second temperature is 860-930°C, the second rolling reduction rate is 60%-90%, the third temperature is 400-500°C, the fourth temperature is 20-30°C, the first cooling rate is 320-420°C / s, and the second cooling rate is 200-300°C / s.

9. The preparation method according to claim 6, characterized in that: The process also includes heating the ingot before rolling, wherein the heating temperature is 1180-1250° C. and the holding time is 120-180 minutes.

10. The preparation method according to claim 6, characterized in that: The offline heat treatment includes quenching and tempering the ingot; The quenching treatment has a holding temperature of 880-930°C, a holding time of 20-40 minutes, and a cooling rate of 300-500°C / s; The holding temperature of the tempering treatment is 190-230° C., the holding time is 15-45 minutes, and the cooling rate is 300-500° C. / s.

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