High-strength, corrosion-resistant steel alloys

Abstract

The invention relates to a high-alloy steel, a use of the high-alloy steel in additive manufacturing, a method for manufacturing a component from the high-alloy steel and a component comprising the high-alloy steel.

Description

The invention relates to a high-alloy steel, to a use of the high-alloy steel in additive manufacturing, to a method for producing components comprising the high-alloy steel and to a component comprising the high-alloy steel.Technological BackgroundSteels are still the most important group of materials in plant and mechanical engineering. The reasons for this are, for example, that the technological properties can be adjusted over very wide ranges and the production as well as the processing methods are established and standardized to a great extent with regard to the achievable qualities. Nevertheless, the common and also available alloys have mostly already been developed for decades.Due to the success of additive manufacturing, in particular of the 3D printing processes in recent years, new fields of application for steels have also resulted for this purpose. In the 3D printing methods, a higher material utilization can be achieved, so that the essentially powder-metallurgical or wire-based additive routes are known to offer savings potentials for material, energy and time. The steels to be used should in principle be as high as possible, light, chemically resistant, easily processable and low-warpage. The latter suggests that high-temperature treatments can be dispensed with as much as possible, since these take long times in practice, cause additional costs and can entail the risk of quality losses, for example due to distortion.The corrosion resistance of steels can be achieved by passive layers which require a corresponding alloy content of chromium of typically 13%. In this connection, a higher carbon concentration becomes critical for increasing the strength, or requires very special heat treatments. Although this alloy concept would be advantageous for a lower density, it would be difficult due to the potential setting of chromium in the form of carbides, which is then no longer available for corrosion protection. In order to overcome this problem, corrosion-resistant steels usually have carbon-free or low-carbon compositions. Instead of carbon, the strength can be increased by intermetallic or purely metallic precipitations. Nevertheless, corrosion-resistant steels with a high strength can usually only be treated with complicated post-treatment steps such as high-temperature homogenization at more than 800° C. and rapid cooling and optionally. In this case, deep cooling can be obtained. After intensive research work, a highly alloyed steel has now been found which is corrosion-resistant and which can be surprisingly provided with high-strength properties by means of an advantageous heat treatment, which make it particularly suitable for processing via additive manufacturing methods from the melt.SUMMARY OF THE INVENTIONThe invention relates to a high alloy steel.The steel comprises (i) chromium in a mass proportion in the range of 14.5 wt % to 17.5 wt %, preferably 15.0 wt % to 16.5 wt %, (ii) nickel in a mass proportion in the range of 6.0 wt % to 12.0 wt %, preferably 7.0 wt % to 9.0 wt %, (iii) molybdenum in a mass proportion in the range of 1.0 wt % to 6.0 wt %, preferably 2.0 wt % to 2.5 wt %, (iv) titanium in a mass proportion in the range of 0.5 wt % to 1.8 wt %, preferably 0.7 wt % to 1.6 wt %, (v) copper in a mass proportion in the range from 1.0% by weight to 3.0% by weight, preferably 1.5% by weight to 2.5% by weight, (vi) silicon in a mass proportion in the range from 0.5% by weight to 1.0% by weight, preferably 0.7% by weight to 0.9% by weight, (vii) manganese in a mass proportion in the range from 0.5% by weight to 1.0% by weight, preferably 0.6% by weight to 0.9% by weight, (viii) niobium in a mass proportion in the range from 0.0% by weight to 1.0% by weight, preferably 0.2% by weight to 0.5% by weight, (ix) carbon in a mass proportion in the range from 0.00 wt % to 0.05 wt %, preferably 0.00 wt % to 0.03 wt %, and (x) iron as the main constituent.The invention also relates to the use of the high-alloy steel described herein in the additive manufacturing of components.The invention also relates to a method for producing a component.The method is characterized in that it comprises the following steps: i) providing a high-alloy steel as described herein in powder or wire form ii) forming a layer of melt of the high-alloy steel on a base iii) cooling the melt layer to a temperature of <400 °C with a cooling rate of >250 K s -1, preferably in a range of 250 K s -1 to 3000 K s -1, particularly preferably of 500 K s -1 to 2000 K s -1, even more preferably of 500 K s -1 to 1500 K s -1, iv) repeating steps i) - iii), wherein the next layer in each case is formed on the preceding layer until the desired shape of the component is obtained, v) depositing the component obtained after step iv) at a temperature in the range from 400° C. to 600° C., preferably 450° C. to 580° C., wherein a high-strength component is obtained after cooling.The invention also relates to a component comprising the high alloy steel described herein.DETAILED DESCRIPTION OF THE INVENTIONThe invention relates to a high alloy steel. Steel is a material which consists predominantly of iron and is alloyed with further elements. "High-alloy" in this disclosure means that at least one alloying element is present to an extent of more than 5 wt %.Composition of high alloy steelChromium: Chromium:Chromium is typically alloyed to steel to increase corrosion resistance. Steel alloys with a chromium content of >13 wt % are usually considered corrosion-resistant.The inventive steel comprises chromium in a mass proportion in the range of 14.5 wt % to 17.5 wt %, preferably 15.0 wt % to 16.5 wt %.High corrosion resistance can thereby be ensuredNickel: Nickel:Nickel increases toughness (workability) and makes steels resistant to special forms of corrosion. In addition, it may form precipitates together with other alloy components, such as titanium Ni 3 Ti or aluminum Ni 3 Al.The inventive steel comprises nickel in a mass proportion in the range from 6.0 wt % to 12.0 wt %, preferably 7.0 wt % to 9.0 wt %.Molybdenum:Molybdenum also increases the corrosion resistance, for example resistance to general area corrosion, of steels. However, the oscillability and extensibility may deteriorate if it is present in too large a proportion by mass. Therefore, it usually becomes max. 5% by weight.The inventive steel comprises molybdenum in a mass proportion in the range from 1.0% by weight to 6.0% by weight, preferably 2.0% by weight to 2.5% by weight.Titanium: Titanium:Titanium gives steel a high toughness, strength and ductility even in low concentrations, and can form precipitates with nickel Ni 3 Ti.The inventive steel comprises titanium in a mass proportion in the range from 0.5 wt % to 1.8 wt %, preferably 0.7 wt % to 1.6 wt %.Copper: Copper:Copper is conventionally used in precipitation hardening steels to form metallic precipitates which greatly increase the strength. Copper is soluble in a steel with an austenite phase, but not in a steel with a ferrite phase. The copper precipitates from the ferrite phase and forms inherent, very small precipitation phases, usually in the nm range. This precipitation takes place in a low-temperature treatment, also called aging, which is usually carried out at a temperature of about 500° C. In order for the precipitations to achieve the desired effect, they should be distributed as homogeneously as possible in the steel. For this reason precipitation-hardening steels are usually homogenized at temperatures of above 800° C.The inventive steel comprises copper in a mass proportion in the range from 1.0% by weight to 3.0% by weight, preferably 1.5% by weight to 2.5% by weight.Silicon:Silicon increases the strength of steels, but can lead to brittleness at too high a mass fraction and is usually added by alloying to 1 wt %.The inventive steel comprises silicon in a mass proportion in the range from 0.5 wt % to 1.0 wt %, preferably 0.7 wt % to 0.9 wt %.Manganese: Manganese:Manganese behaves similarly to silicon in that it increases the strength of steels, but can lead to brittleness at too high a mass fraction. Manganese is therefore usually added by alloying to 2% by weight.The inventive steel comprises manganese in a mass proportion in the range from 0.5 wt % to 1.0 wt %, preferably 0.6 wt % to 0.9 wt %.Niobium: Niobium:Niobium, as an alloying element in ferritic steels, stabilizes impurities such as C and O and can thereby increase the corrosion resistance. Furthermore, a grain-refining effect is observed in martensitic steels. The inventive steel comprises niobium in a mass proportion of 0.0% by weight to 1.0% by weight, preferably 0.2% by weight to 0.5% by weight.Carbon:Although carbon can lead to a great increase in strength in steels, due to the potential carbide formation it is, however, more readily avoided in modern, corrosion-resistant high-performance steels and the mass fraction in the corresponding steels is reduced below the usual detection limits.Also in the present inventive steel alloy, the mass fraction of carbon is in the range of 0.00 wt % to 0.05 wt %, preferably 0.00 wt % to 0.03 wt %. Accordingly, it is advantageous if no, or only an unavoidable, amount of contamination of carbon is present in the inventive steel.Iron: Iron:Iron is the major constituent of steel. Iron is preferably present in the steel according to the invention in a mass fraction of more than 50% by weight, more preferably in the range from 55% by weight to 75% by weight, particularly preferably 65% by weight to 75% by weight.Steel Contaminants:Contamination of the inventive steel with the elements phosphorus, sulfur and / or nitrogen can also occur.These elements are preferably present independently of one another in each case only in a mass fraction in the range from 0.000 wt % to 0.015 wt % in the steel alloy.Cobalt: Cobalt:The alloying of cobalt is generally avoided because of its high initial costs and difficultly appreciated effects on the steel. In precipitation-hardening steels based on Ni 3 Ti or Ni 3 Al precipitations, however, it is realloyed, since it supports the local precipitation formation by spiodal segregation.The inventive steel may therefore comprise cobalt in a mass proportion in the range of 0.1 wt % to 14.0 wt %. Preferably, the sum of the mass fractions of cobalt and nickel in the inventive steel is less than 20% by weight.Aluminum: Aluminum:Aluminum is an element which is added to the corrosion-resistant steels in order to increase the resistance to scale, but in connection with nickel in particular can also form strength-enhancing precipitates, so that it can optionally be alloyed.The inventive steel may therefore contain aluminum in a mass proportion in the range from 0.0% by weight to 1.5% by weight.All mass fractions are based on the total mass of the steel.The mass fractions of the elements of the inventive steels can only be selected from the respective ranges specified in such a way that the sum of the mass fractions of all the elements present does not exceed 100% by weight.Additional alloying additions are not necessary to achieve the primary properties of the inventive steel. The addition of further elements in small mass proportions is conceivable, however, provided that the inventive properties of the particular structure formation are not impaired as a result.The steel according to the invention preferably comprises no further metals other than the metals mentioned, i.e. Chromium, nickel, molybdenum, silicon, manganese, copper, titanium, niobium, iron and optionally aluminum and / or cobalt.The properties of steels depend on the internal structure of the steels, the so-called structure.The structure contains the matrix and the so-called precipitates.The matrix of steels can consist of the phases austenite (cubic surface-centered lattice structure), ferrite (cubic space-centered lattice structure) and martensite (cubic space-centered or tetragonal space-centered lattice structure). In the case of highly alloyed steels, mixed phases are usually formed, for example the matrix can be present to an extent of 90% in an austenitic phase and to an extent of 10% in a ferritic phase. The proportions of the respective phases can be determined, for example, by radiography.A high proportion of austenite phase generally leads to a comparatively ductile and readily deformable steel. A high proportion of ferrite phase generally leads to a higher-strength steel. An increasing proportion of martensite phase can lead to a further hardening of the steel.Which of the phases and in what proportion they form depends on the chemical composition (elements) and the conditions of formation (from the melt, from a heat treatment, with or without rapid cooling).According to the Schaeffler / DeLong diagram (Schaeffler diagram, FIG. 1 ), the occurrence of the phases can be predicted, especially for corrosion-resistant steels, starting from the mass fractions of specific elements.The basic assumption for this is that the corresponding steels were previously heated (homogenized) to about 1,050° C. and then cooled very rapidly, which corresponds to the standard in conventional production.In order to predict the respective proportions of the phases, the so-called chromium and nickel equivalents of the steel must be calculated.Chromium Equivalent:The chromium equivalent is a measurement for the entirety of the ferrite-forming elements (chromium, silicon and molybdenum) of an austenitic stainless steel alloy, according to the empirical formula (I) of Schaeffler / DeLong (Schaeffler diagram), wherein the effects of the elements besides chromium are weighted accordingly on the basis of empirical findings in relation to chromium.The chromium equivalent of the inventive steels preferably satisfies the condition:Nickel equivalent:The nickel equivalent is a measurement for the entirety of the austenite-forming elements (nickel, carbon, nitrogen, manganese, copper and cobalt) of an austenitic steel alloy according to the empirical formula (II) of Schaeffler / DeLong (Schaeffler diagram), wherein the effects of the elements besides nickel are weighted accordingly on the basis of empirical findings in relation to nickel.The nickel equivalent of the inventive steels preferably satisfies the condition:FIG. 1 shows a Schaeffler / DeLong diagram. The matrix of the inventive steels should according to the diagram have a high proportion of austenite phase and possibly a small proportion of ferrite or martensite. Thus, they would be unsuitable for precipitation hardening steel because the copper to be precipitated and the Ni 3 Ti would remain dissolved in the austenite phase.However, it has surprisingly been found that the matrix of the inventive steels having the element composition described herein and the corresponding mass fractions is present to an extent of more than 70% in a ferritic phase after rapid cooling to a temperature of <400 ° C. from the melt. Preferably, the proportion of ferritic phase in the matrix is in the range of 70% to 100%, more preferably 90% to 100%.The cooling rate is preferably more than 250 K s -1, preferably in a range from 250 K s -1 to 3000 K s -1, particularly preferably from 500 K s -1 to 2000 K s -1, even more preferably from 500 K s -1 to 1500 K s -1.In the ferrite phase which is then present, the copper and the further precipitation-forming elements, for example Ni and Ti, remain positively dissolved at room temperature and the desired precipitation phases of metallic copper and Ni 3 Ti or Ni 3 Al phases are formed by diffusion processes only in a heat treatment in a range from 400 to 600° C., preferably 450° C. to 580° C., in the case of so-called aging. Such aging can be carried out for a period of from 0.1 h to 8 h, preferably from 1 h to 7 h, more preferably from 3 h to 5 h.After the aging, the steels according to the invention have a high strength, high corrosion resistance and high hardness, without having to be subjected to a high-temperature post-treatment at more than 800° C.Use of the high alloy steel of the present inventionThe inventive, high-alloy steels are therefore ideal for use in the additive manufacturing of components (generally speaking, commonly referred to as 3D printing methods) and coatings of materials or components.The steel according to the invention is particularly suitable for all those additive manufacturing methods which a) produce a melting phase which rapidly solidifies on a previously produced / present substrate or b) does not adversely alter a ferritic microstructure according to the invention which is already present in the starting material, e.g. steel powder or steel wire, in the processing process, e.g. by austenite formation.Group a) includes the best known so-called powder bed fusion of metals (PBF-LB / M), frequently also referred to as "selective laser melting" (SLM), which is the most widely used currently in industry. A very similar method uses electron beams as the energy source for melting the powder layers (PBF-EB). However, there is still a whole series of further methods which meet the requirements mentioned, for example methods of so-called direct energy deposition (DED), in which powder or wire is melted and locally applied in a controlled manner to a substrate by means of an energy source (laser, electron beam, plasma, arc), where the material rapidly solidifies and cools. These processes conventionally also include the industrially established so-called build-up welding and, in the broader sense, also thermal spraying processes such as plasma or flame spraying, which are predominantly used for layer production, but are likewise suitable for processing the stated steel with properties which can be achieved according to the invention to give layer layers.Group b) includes so-called cold gas spraying, in which the powder is not melted, but rather is heated only briefly and accelerated to a very high speed, so that it bonds to the substrate, ideally in a materially continuous manner, when it hits the substrate. The thermal stress on the powder can be briefly above 1000° C., but only occurs in the range of ms, so that changes in structure as a rule do not play a role.At present, experimental methods of additive manufacturing can also be assigned to this group, such as, for example, the layer structure in which the material deposition and application takes place via frictional energy.Method for Producing a Component:The invention relates to a method for producing a component, characterized in that the method comprises the following steps:Provision of the High Alloy Steel According to the Invention Step i)In order to be able to be used in additive manufacturing, the inventive steel alloy, as described herein, must first be converted into a suitable shape. Suitable shapes are powder or wire.Methods for producing such steel powders or wires are known to the person skilled in the art.Steel powders for additive manufacturing, build-up welding or thermal spraying are obtained predominantly by gas atomization. An inert gas, such as argon or nitrogen, acts on a melt stream of the steel alloy, thereby finely distributing it and rapidly cooling the fragments produced. The fragments generally solidify as spherical particles, so that a steel powder produced in this way has good flowability. Further methods are familiar to the skilled worker, such as, for example, plasma atomization, water and oil atomization or rotary atomization, these frequently having disadvantages for the application, such as higher costs, contamination (O, C), restrictions on the particle fineness which can be achieved or brittle particle shapes.The diameter value d 50(= value at 50% by weight of a cumulative distribution) of the spherical steel powder particles can be in a range from about 10 μm to about 300 μm.For different applications, the specific particle size ranges required in each case are separated off by classifying the steel powder. Thus, particles with a size of 5 μm to 60 μm (laser melting) or of 60 μm to 160 μm (electron beam melting) are typically used for the powder bed-based methods (lower and upper limits), for the methods of DED and build-up welding of approximately 50 μm to 150 μm or to 300 μm, for the cold gas spraying of 5 μm to 30 μm and for other thermal spraying methods of 10 μm to 30 μm (high-speed flame spraying), 20 μm to 50 μm (flame spraying) or of 20 μm to 120 μm (plasma spraying).In the present method, a steel powder having a diameter value d 50 of the spherical steel powder particles in a range of 10 μm to 100 μm is preferably used.The diameter value d 50 identifies the particle size which has a total passage value of 50% by weight. Thus, 50% by weight of the particle sizes in the powder are smaller and 50% by weight larger than this value.The steel powder produced in this way can then be used in the additive manufacturing of a component.Methods for wire manufacturing are state of the art and are known to the person skilled in the art. For the processing techniques of additive manufacturing and layer production (build-up welding) that are considered, wires with diameters between typically 1 mm and 3 mm are used.Melting step ii)Step ii) relates to forming a layer of melt of the high alloy steel on a substrate.Methods for forming a layer from melt are known to the person skilled in the art. When steel powder is used, the method is preferably selected from laser or electron beam printing.When steel wire is used, the method is preferably selected from laser, arc, plasma or electron beam build-up welding.The melt layer is preferably obtained by applying a steel powder layer and subsequently locally melting the powder layer or by melting a particle jet from the steel powder directed onto the component. In the case of the wire methods, melting is preferably carried out by means of energy sources mentioned in the immediate vicinity of or in contact with the component or the preceding layer.The base may be a different material which remains a part of the component obtained, a material which is removed from the component again after the method, or, according to step iv), a previously produced layer of the steel according to the invention.Cooling step iii)After the formation of the melt layer in step ii), the melt in step iii) must be rapidly cooled to a temperature <400 °C.The cooling rate is >250 K s -1, preferably in a range from 250 K s -1 to 3000 K s -1, particularly preferably from 500 K s -1 to 2000 K s -1, even more preferably from 500 K s -1 to 1500 K s -1.A ferritic structure is produced by rapid cooling and premature precipitation of the dissolved elements Cu and Ni and titanium as Ni 3 Ti is prevented. These remain positively dissolved in the ferritic phase.These cooling rates can easily be achieved if melting methods such as laser and electron beam pressure / build-up welding or plasma or arc build-up welding are used, since the energy input takes place only briefly and locally limited in this case, that is to say only small melt volumes are generated, from which the heat dissipation via the environment takes place quickly, which leads to rapid solidification and high cooling rates.Additive Manufacturing Component Step iv)The component is then built up layer by layer by repeating steps i) to iii) until the desired shape of the component is obtained. In this case, the respective next layer is formed on the preceding layer. Additive manufacturing methods are known to those skilled in the art and know how to select the exact shape and sequence of layers in order to obtain the desired shape of the component.Aging Step v)After the component has been obtained according to steps i) to iv), the highly alloyed steel layers still do not have a high strength, since the potential precipitation elements and alloys Cu and Ni 3 Ti are positively dissolved in the ferritic steel matrix.Only the aging step v), in which the component or coated component is exposed to a temperature in the range from 400° C. to 600° C., preferably 450° C. to 580° C., leads to the corresponding formation of the precipitates of elemental copper and Ni 3 Ti phases.The heat treatment step v) can be carried out for a duration of 0.1 h to 8 h, preferably 1 h to 7 h, more preferably 3 h to 5 h.After cooling, the component possesses high-strength properties.Optional Heat Treatment Step vi)After obtaining the component from step sequences i) to v), the steel has high-strength properties, which at the same time results in reduced ductility. Ductile or ductility is the property of a material to plastically deform under load before it fails.An increase in ductility can be brought about by a heat treatment step vi) in which the component is exposed to a temperature in the range from 800° C. to 1200° C., preferably 850° C. to 1100° C., since austenitizing of the structure occurs in this temperature range.The optional heat treatment is preferably carried out locally in order to set ductile regions on the component according to its mechanical stress profile, which regions can be set locally and / or in a graded manner. Corresponding methods for the time-limited and spatially limited temperature treatment are known to the person skilled in the art, for example inductive heating or laser irradiation.The component obtained is preferably not subjected to any further heat treatment step after steps i) to v) or i) to vi).ComponentThe invention also relates to a component comprising the inventive steel described herein. The methods described herein may be used to produce the component.The component may consist of the steel according to the invention.However, it is also possible, in particular in connection with the methods of build-up welding or thermal spraying, to apply the inventive steel to other materials and to connect it to these materials.Consequently, the component may be coated with the inventive steel.However, the steel should remain unchanged in order to be able to carry out the subsequent heat treatments according to the invention. The skilled person for such application methods is aware that he should in this case observe technical restrictions, such as, for example, a mixture of the steel with the different base material (application welding) or too great differences in the coefficient of thermal expansion (thermal spraying).Ductility: DuctilityThe matrix of the inventive steel is present to an extent of more than 70% in a ferritic phase. By heating to more than 800° C., preferably in a range from 800° C. to 1200° C., the ferritic phase can be transformed into an austenitic phase (austenitizing), which leads to a higher ductility.This property of the inventive steel can be exploited to produce more ductile regions in an otherwise high strength steel by a local heat treatment.A high-strength component with local, ductile regions can be, for example, a shaft that is loaded differently over the cross section or simply just a razor.The invention is also described by the following numbered aspects: 1. a high-alloy steel, characterized in that the steel comprises (i) chromium in a mass fraction in the range from 14.5 wt % to 17.5 wt %, preferably 15.0 wt % to 16.5 wt %, (ii) nickel in a mass fraction in the range from 6.0 wt % to 12.0 wt %, preferably 7.0 wt % to 9.0 wt %, (iii) molybdenum in a mass fraction in the range from 1.0 wt % to 6.0 wt %, preferably 2.0 wt % to 2.5 wt %, (iv) titanium in a mass fraction in the range from 0.5 wt % to 1.8 wt %, Preferably 0.7% by weight to 1.6% by weight, (v) copper in a mass proportion in the range from 1.0% by weight to 3.0% by weight, preferably 1.5% by weight to 2.5% by weight, (vi) silicon in a mass proportion in the range from 0.5% by weight to 1.0% by weight, preferably 0.7% by weight to 0.9% by weight, (vii) manganese in a mass proportion in the range from 0.5% by weight to 1.0% by weight, preferably 0.6% by weight to 0.9% by weight, (viii) niobium in a mass proportion in the range from 0.0% by weight to 1.0% by weight, preferably 0.2% by weight to 0.5% by weight, (ix) carbon in a mass proportion in the range of 0.00 wt % to 0.05 wt %, preferably 0.00 wt % to 0.03 wt %, and (x) iron as a main component. 2. the high-alloy steel according to aspect 1, characterized in that iron is present in a mass fraction of more than 50% by weight, preferably in the range from 55% by weight to 75% by weight, particularly preferably 65% by weight to 75% by weight. 3. the high-alloy steel according to one of aspects 1 or 2, characterized in that the steel impurities phosphorus, sulfur and nitrogen are present independently of one another in each case in a mass fraction in the range from 0.000 wt % to 0.015 wt % in the steel alloy. 4. the high-alloy steel according to any one of the preceding aspects, characterized in that the steel additionally comprises cobalt in a mass fraction in the range from 0.1 wt % to 14 wt %. 5. the high alloy steel according to aspect 4, characterized in that the sum of the mass fractions of cobalt and nickel in the inventive steel is less than 20 wt %. 6.The high-alloy steel according to one of the preceding aspects, characterized in that the steel additionally comprises aluminium in a mass fraction in the range from 0.1 wt % to 1.5 wt %. 7. the high-alloy steel according to one of the preceding aspects, characterized in that the steel does not comprise any further metals. 8. the high-alloy steel according to one of the preceding aspects, characterized in that the Ni equivalent (Ni-eq.) satisfies the following condition: wherein the Ni equivalent is calculated according to the following formula 9. the high-alloy steel according to one of the preceding aspects, characterized in that the chromium equivalent (Cr-eq.) satisfies the following condition: wherein the Cr equivalent is calculated according to the following formula 10. the high-alloy steel according to one of the preceding aspects, characterized in that the matrix of the high-alloy steel is present to an extent of more than 70%, preferably in the range from 70% to 100%, more preferably from 90% to 100%, in a ferritic phase, determined by radiographic analysis. 11.The high-alloy steel according to aspect 10, characterized in that the ferritic phase is obtained by rapid cooling from the melt at a cooling rate of more than 250 K s -1, preferably in a range from 250 K s -1 to 3000 K s -1, particularly preferably from 500 K s -1 to 2000 K s -1, even more preferably from 500 K s -1 to 1500 K s -1 to a temperature of <400 ° C. 12.A use of the high-alloy steel according to one of aspects 1 to 11 in the additive manufacturing of components. 13.A method for producing a component, characterized in that the method comprises the following steps: i) providing a high-alloy steel according to one of aspects 1 to 11 in powder or wire form ii) forming a layer of melt of the high-alloy steel on a base iii) cooling the melt layer to a temperature of <400 °C at a cooling rate of >250 K s -1, preferably in a range of 250 K s -1 to 3000 K s -1, particularly preferably of 500 K s -1 to 2000 K s -1, even more preferably of 500 K s -1 to 1500 K s -1, iv) repeating steps i) - iii), wherein the respective next layer is formed on the preceding layer until the desired shape of the component is obtained, v) depositing the component obtained after step iv) at a temperature in the range from 400° C. to 600° C., preferably 450° C. to 580° C., wherein a high-strength component is obtained after cooling. 14. the method according to aspect 13, characterized in that the average diameter value d 50 of the steel powder particles in step i) is in a range from 10 μm to 100 μm, preferably 15 μm to 80 μm, particularly preferably 20 μm to 70 μm. 15. The method according to aspect 14, characterized in that the steel wire has a diameter in the range of 1 mm to 3 mm. 16. The method according to any of aspects 13 to 15, characterized in that the melt layer in step ii) is obtained by applying a steel powder layer and subsequent local melting of the powder layer. 17. the method according to any one of aspects 13 to 15, characterized in that the melting layer in step ii) is obtained by melting the steel powder and subsequently applying the molten steel. 18. The method according to any of aspects 13 to 15, characterized in that the fusible layer in step ii) is obtained by melting off a wire. 19.The method according to one of aspects 13 to 18, characterized in that the method for forming a layer of melt in step ii) is selected from the list consisting of laser or electron beam printing, laser or electron beam build-up welding, plasma build-up welding, arc build-up welding or thermal spraying by means of flame, arc or plasma. 20.The method according to any of aspects 13 to 19, characterized in that the heat treatment in step v) is carried out for a duration of 0.1 h to 8 h, preferably 1 h to 7 h, more preferably 3 h to 5 h. 21.The method according to any one of aspects 13 to 20, characterized in that the method comprises a further step vi) after step v), wherein step vi) consists of the following: vi) locally heat-treating the high-strength component obtained after step v) at a temperature in the range of more than 800° C., preferably in a range of 800° C. to 1200° C., more preferably of 900° C. to 1100° C., which results in the formation of regions with higher ductility compared to the rest of the component. 22.A component made of high-alloy steel, characterized in that it comprises the high-alloy steel according to one of aspects 1 to 11. 23.The component according to aspect 22, characterized in that it consists of the highly alloyed steel. 24. the component according to aspect 22, characterized in that the component is coated with the high-alloy steel. 25.The component according to one of aspects 22 to 24, characterized in that it has been produced by a method according to one of aspects 13 to 21. 26. The component according to one of aspects 22 to 25, characterized in that the component has regions with higher ductility compared to the rest of the component. 27. the component according to aspect 26, characterized in that these ductile regions are formed by a local heat treatment at more than 800° C., preferably in a range from 800° C. to 1200° C., even more preferably from 900° C. to 1100° C.Experimental part:Measurement methods:Phase fractions of the various phases in the matrix of the high-alloy steel were determined by radiography.The hardness of the steels was determined by the hardness test according to Vickers, DIN EN ISO 6507-1 to 4.Yield strength, tensile strength and elongation at break were determined in a metal tensile test according to ISO 6892-1.Inventive Example:A high alloy steel having a composition as in Table 1 was prepared. Table 1: Composition of the inventive steel alloy Table 1: Composition of the inventive steel alloy% by weightRemainder: Remainder:16,08,52,31,32,00,80,80,3Argon atomization was used to obtain a spherical steel powder having d 50= 48 μm. A component was built from this powder using a 3D Systems ProX DMP 200 laser system. The cooling rate of the melt layers was above 1000 K s -1.The finished component was removed from storage at 530° C. for 4 hours.Table 2 shows the physical properties of the component in the cooled state at room temperature: directly after construction, after the aging step for setting high-strength properties, and after an optional second aging for setting ductile properties. Table 2: Properties of the component after construction and after demounting. Table 2: Properties of the component after construction and after demounting.Built98 % ferrite, 2% austenite320 HV899 MPa953 MPa24,4 %Built and Stored at 530° C98 % Ferrite 2% Austenite540 HV1700 MPa1716 MPa8,5 %After 2nd aging at 1050° C5 % ferrite 95% austenite195 HV362 MPa655 MPa40,6 %The precipitation phases of Cu and Ni 3 Ti formed in the aging step at 530° C. lead to a very high hardness and tensile strength of the component at a lower elongation at break.If the component is homogenized for one hour after the aging step at 530° C. in a high-temperature annealing step at 1050° C. and then cooled to room temperature, a stable austenite phase (95%) without precipitates is formed, since the Cu remains dissolved in the austenite phase and no Ni 3 Ti precipitates form. The component had a low hardness of 195 HV and an elongation at break of over 40%.

Claims

A high-alloy steel, characterized in that the steel (i) chromium in a mass proportion in the range from 14.5 wt.% to 17.5 wt.%, preferably 15.0 wt.% to 16.5 wt.%, (ii) nickel in a mass proportion in the range from 6.0 wt.% to 12.0 wt.%, preferably 7.0 wt.% to 9.0 wt.%, (iii) molybdenum in a mass proportion in the range from 1.0 wt.% to 6.0 wt.%, preferably 2.0 wt.% to 2.5 wt.%, (iv) titanium in a mass proportion in the range from 0.5 wt.% to 1.8 wt.%, preferably 0.7 wt.% to 1.6 wt.%, (v) copper in a mass proportion in the range from 1.0% by weight to 3.0% by weight, preferably 1.5% by weight to 2.5% by weight, (vi) silicon in a mass proportion in the range from 0.5% by weight to 1.0% by weight, preferably 0.7% by weight to 0.9% by weight, (vii) manganese in a mass proportion in the range from 0.5% by weight to 1.0% by weight, preferably 0.6% by weight to 0.9% by weight, (viii) niobium in a mass proportion in the range from 0.0% by weight to 1.0% by weight, preferably 0.2% by weight to 0.5% by weight, (ix) carbon in a mass proportion in the range of 0.00 wt % to 0.05 wt %, preferably 0.00 wt % to 0.03 wt %, and (x) iron as a main component.The high-alloy steel according to claim 1, characterized in that iron is present in a mass proportion of more than 50 wt.%, preferably in the range of 55 wt.% to 75 wt.%, particularly preferably 65 wt.% to 75 wt.%.The high-alloy steel according to any one of claims 1 or 2, characterized in that the steel additionally comprises one or more of the following components: - steel impurities phosphorus, sulfur and nitrogen, each independently of one another in a mass proportion in the range of 0.000 wt.% to 0.015 wt.%, and / or - cobalt in a mass proportion in the range of 0.1 wt.% to 14 wt.%, and / or - aluminum in a mass proportion in the range of 0.1 wt.% to 1.5 wt.%.The high-alloy steel according to any one of the preceding claims, characterized in that the Ni equivalent (Ni-eq.) satisfies the following condition: Ni - A%0020̈ q. ≥ 8.5, wherein the Ni equivalent is calculated according to the following formula: Ni - A%0020̈ q. = wt.-%Ni + 30 * (wt.-% C + wt.-% N) + 0.5 * (wt.-% Mn + wt.-% Cu + wt.-% Co), and / or that the chromium equivalent (Cr-eq.) satisfies the following condition: Cr - A%0020̈ q. ≥ 18, wherein the Cr equivalent is calculated according to the following formula: Cr - A%0020̈ q. = wt.-% Cr + 1.5 * wt.-% Si + wt.-% Mo. The high-alloy steel according to any one of the preceding claims, characterized in that the matrix of the high-alloy steel is present to an extent of more than 70%, preferably in the range from 70% to 100%, more preferably from 90% to 100%, in a ferritic phase, determined by radiographic analysis.Use of the high-alloy steel according to one of Claims 1 to 5 in the additive manufacturing of components.A method for producing a component, characterized in that the method comprises the following steps: i) providing a high-alloy steel according to any one of claims 1 to 5 in powder or wire form ii) forming a layer of melt of the high-alloy steel on a substrate iii) cooling the melt layer to a temperature of < 400°C at a cooling rate of > 250 K s -1, preferably in a range of 250 K s -1 to 3000 K s -1, particularly preferably of 500 K s -1 to 2000 K s -1, even more preferably of 500 K s -1 to 1500 K s -1, iv) repeating steps i) - iii), wherein the respective next layer is formed on the preceding layer until the desired shape of the component is obtained, v) depositing the component obtained after step iv) at a temperature in the range from 400° C. to 600° C., preferably 450° C. to 580° C., wherein a high-strength component is obtained after cooling.The method according to claim 7, characterized in that the heat treatment in step v) is carried out for a duration of 0.1 h to 8 h, preferably 1 h to 7 h, more preferably 3 h to 5 h.The method according to any of claims 7 or 8, characterized in that the method comprises after step v) a further step vi), wherein step vi) is as follows: vi) local heat treating the high strength component obtained after step v) at a temperature in the range of more than 800°C, preferably in a range of 800°C to 1200°C, more preferably of 900°C to 1100°C, resulting in the formation of regions with higher ductility compared to the rest of the component.A component characterized in that it comprises the high alloy steel according to any one of claims 1 to 5.

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