3D Printable Hard Iron-Based Metal Alloys for Powder Bed Fusion

Abstract

To provide an alloy composition for 3D metal printing processes that provides metal parts with high hardness, tensile strength, yield strength, and ductility. The alloy contains Fe, Cr, and Mo, and at least three or more elements selected from C, Ni, Cu, Nb, Si, and N. The as-built component exhibits a tensile strength of at least 1000 MPa, a yield strength of at least 640 MPa, a ductility of at least 3.0%, and a hardness (HV) of at least 375.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 415,667, filed November 1, 2016, which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to alloy compositions and 3D printing procedures for providing the formation of metal parts having relatively high hardness, tensile strength, yield strength, and elongation. The alloys also exhibit the ability to form desired phases, such as metal carbide and / or metal carbonitride phases, that contribute to such mechanical property characteristics. [Background technology]

[0003] Metal 3D printing processes offer numerous exceptional advantages, including the ability to produce highly complex parts with significantly reduced part production times. For these reasons, 3D printing is highly valuable to many industries. While many 3D printing processes exist for building metal parts, the most widely adopted processes utilize a solid-liquid-solid transformation to build the part. These processes are commonly referred to as powder bed fusion (PBF), selective laser melting (SLM), and electron beam melting (EBM); hereafter, these processes will be referred to as PBF.

[0004] While PBF is highly versatile in its ability to produce complex parts from certain metal alloys, the process has been limited to its ability to produce parts from a relatively small number of steel alloys, such as 316L, 17-4PH, and maraging steel M300. Of these alloys, only M300 has a hardness (HV>370) that is considered sufficient to classify the alloy as a hard alloy.

[0005] The expansion of hard PBF steel alloys has encountered a variety of issues, particularly the occurrence of crack formation during or after the printing process. Cracking in parts can be caused by a number of factors, including thermal stress, hot tearing, and liquation cracking, and generally, the likelihood of cracking increases as the hardness of the built part increases and the toughness decreases.

[0006] Many industries are interested in utilizing PBF in higher hardness materials (HV>370) for applications such as tooling, dies, molds, cutting tools, gears, filters, and bearings. In addition to high hardness, these applications also generally require high strength, toughness, and corrosion resistance, low environmental health, low safety and management risks, and low cost. Summary of the Invention [Means for solving the problem]

[0007] A method for layer-by-layer construction of a metal part comprises the steps of providing an iron-based alloy in particulate form, the iron-based alloy comprising the elements Cr and Mo, and at least three elements from the group consisting of C, Ni, Cu, Nb, Si, and N, wherein Cr is present at 10.0 wt.% to 19.0 wt.%, Mo is present at 0.5 wt.% to 3.0 wt.%, C is present at 0 to 0.35 wt.%, Ni is present at 0 to 4.0 wt.%, Cu is present at 0 to 5.0 wt.%, Nb is present at 0 to 1.0 wt.%, Si is present at 0 to 1.0 wt.%, N is present at 0 to 0.25 wt.%, and the remainder of the alloy composition comprises Fe; forming one or more layers of the alloy by melting the alloy to a molten state and cooling to form solidified layers of the elements, each solid layer having a thickness comprised between 2.0 microns and 200.0 microns, wherein the metal part comprising the one or more layers has the following properties: tensile strength of at least 1000 MPa, yield strength of at least 640 MPa, elongation of at least 3.0%, and hardness (HV) of at least 375.

[0008] The present invention also relates to a 3D printed metal part, comprising one or more iron-based metal alloy layers comprising the elements Cr and Mo, and at least three elements from C, Ni, Cu, Nb, Si and N, wherein Cr is present at 10.0 wt.% to 19.0 wt.%, Mo is present at 0.5 wt.% to 3.0 wt.%, C is present at 0 to 0.35 wt.%, Ni is present at 0 to 5.0 wt.%, Cu is present at 0 to 5.0 wt.%, Nb is present at 0 to 1.0 wt.%, Si is present at 0 to 1.0 wt.%, and N is present at 0 to 0.25 wt.%, and the remainder of the alloy composition contains Fe; the layer has a thickness in the range of 2.0 microns to 200.0 microns; The printed metal part exhibits a tensile strength of at least 1000 MPa, a yield strength of at least 640 MPa, an elongation of at least 3.0%, and a hardness (HV) of at least 375. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 11 is an optical image of Alloy 1 (A10) built on an SLM 280 HL machine. [Figure 2] FIG. 11 is an optical image of Alloy 1 (A10) built on a Trumpf TRUMAFORM LF 250 PBF machine. [Figure 3] Optical image of Alloy 1 (A10) built on an EOS machine with a density of over 99.5%. [Figure 4] 1 shows an SEM micrograph of as-built alloy 1 (A10) at 10,000x magnification. [Figure 5] 1 shows the equilibrium phase diagram for Alloy 1 prepared in Thermo-Calc. [Figure 6] Figure 1 shows the microstructure at the surface of a part made of Alloy 5 (Table 1) at two different magnifications after carburization. [Figure 7] 1 shows hardness as a function of depth for case-hardened Alloy 5 and Alloy 8 (Table 1). [Figure 8]Figure 1 shows the microstructure at the surface of a part of Alloy 9 (Table 1) at two different magnifications after nitriding. [Figure 9] 1 shows hardness as a function of depth for nitride case-hardened alloys 8 and 9 (Table 1). DETAILED DESCRIPTION OF THE INVENTION

[0010] A new class of alloy steels has been developed that combines high hardness (>375 HV), high yield and tensile strength, and high elongation in both the "as-built" and "heat-treated" condition, as well as excellent printability with low EH&S risks, management risks, and relatively low cost.

[0011] The printability of an alloy is defined as the ease with which the metal alloy can be printed on various commercially available PBF machines without cracking or excessive porosity in the built part. As used herein, the as-built state is understood to be the state of the PBF built part upon removal from the PBF machine, i.e., without any post-build heat treatment. As used herein, the heat-treated state is understood to be the state of the PBF built part after it has undergone a post-build heat treatment. The alloys herein are capable of 3D printing, which refers to a process for creating three-dimensional objects.

[0012] Table 1 below shows the alloy chemistries preferably employed herein, which include Alloy 1 (A10) and then 10 additional alloys, for a total of 11 alloys.

[0013] [Table 1]

[0014] Thus, it can be seen from the above that a metal alloy in particulate form is provided comprising, consisting essentially of, or consisting of at least three or more elements from Fe, Cr, and Mo, and C, Ni, Cu, Nb, Si, and N, where Cr is present at 10.0 wt.% to 19.0 wt.%, Mo is present at 0.5 wt.% to 3.0 wt.%, C is present at 0 to 0.35 wt.%, Ni is present at 0 to 5.0 wt.%, Cu is present at 0 to 5.0 wt.%, Nb is present at 0 to 1.0 wt.%, Si is present at 0 to 1.0 wt.%, and N is present at 0 to 0.25 wt.%. The balance of the alloy composition contains Fe. Thus, for a given alloy formulation, four, five, or all six elements from C, Ni, Cu, Nb, Si, and N can be selected.

[0015] In a preferred embodiment, there is again provided a metal alloy in particulate form comprising, consisting essentially of, or consisting of Fe, Cr, and Mo, and at least three or more elements from C, Ni, Cu, Nb, Si, and N, wherein Cr is present at 10.0 wt.% to 18.3 wt.%, Mo is present at 0.5 wt.% to 2.5 wt.%, C is present at 0 to 0.30 wt.%, Ni is present at 0 to 4.0 wt.%, Cu is present at 0 to 4.0 wt.%, Nb is present at 0 to 0.7 wt.%, Si is present at 0 to 0.7 wt.%, and N is present at 0 to 0.25 wt.%, with the balance of said alloy composition comprising Fe.

[0016] Additionally, the present alloy may contain some unavoidable impurities, and the level of such impurities may be up to 1.0 wt.%. For example, elements not listed above may also be present at levels up to 1.0 wt.%, and then the corresponding level of Fe may be reduced by 1.0 wt.%. With respect to impurities, it is noted that such are expected to include elements such as sulfur, phosphorus, and oxygen.

[0017] Alloy 1, previously designated as Alloy A10, may itself have the following preferred composition: 82.0 to 86.0 wt.% Fe, 10.5 to 12.0 wt.% Cr, 1.5 to 2.5 wt.% Ni, 0.4 to 0.7 wt.% Cu, 1.2 to 1.8 wt.% Mo, 0.14 to 0.18 wt.% C, 0.02 to 0.05 wt.% Nb, 0.04 to 0.07 wt.% N, and 0 to 1.0 wt.% Si.

[0018] The metal alloy is fed to the PBF process in the form of powder particles or wire, preferably produced using conventional melting with gas or centrifugal atomization, utilizing gases such as nitrogen or argon gas, or with water atomization. Nitrogen gas melting and atomization can be used to increase the nitrogen content in the powder alloy. The powder particles can have diameters ranging from 1 to 200 microns, more preferably 3 to 70 microns, and most preferably 15 to 53 microns.

[0019] PBF parts are preferably constructed from the metal alloys herein using commercially available conventional PBF machines, such as the SLM® 280HL or EOS M-280, and the Trumpf TRUMAFORM LF 250. Parts are preferably constructed in a nitrogen or argon atmosphere. Parts may be constructed on metal substrates that are preheated to a temperature in the range of 100°C to 300°C, more preferably in the range of 20°C to 200°C, up to 300°C. In addition, substrates without preheating may also be employed. For the PBF procedures herein, a pressure of 30 to 500 J / m 3 , more preferably 50 J / mm 3 to 300 J / m 3 in the range of 60 J / mm 3 to 200 J / mm 3 One or more lasers or electron beams having energy densities in the range of

[0020] The metal substrate is preferably constructed from alloys 1 to 11 in Table 1, or other materials, such as 304L stainless steel. The PBF procedures herein contemplate the buildup of individual layers, each having a thickness typically ranging from 2.0 microns to 200.0 microns, more preferably from 5.0 microns to 150.0 microns, and most preferably from 5.0 microns to 120.0 microns. Thus, a suitable range of buildup layer thickness is 2.0 microns or greater. However, more typically, the thickness range of the buildup layer (combination of individual layers) is from 2 microns to 800 microns, and even higher depending on the capabilities or requirements of a given printing procedure.

[0021] Porosity and cracking within a part can adversely affect many part properties, including strength, toughness, and fatigue resistance. As such, for dense parts, it is desirable to minimize porosity and cracking in PBF parts. While some larger parts can tolerate higher porosity levels, such as porosity greater than 1.0% to 15.0%, the porosity within a part is preferably less than 1.0%, more preferably less than 0.5%, and most preferably less than 0.2%. The low porosity and lack of cracking in as-built PBF parts containing the metal alloys herein is evidenced in the cross-sectional optical microscope images shown in Figures 1 through 3, which were obtained from parts constructed with Alloy 1 (A10) on SLM 280HL and Trumpf TRUMAFOR LF 250 PBF machines, and EOS M280 / 290, respectively. The parts shown in Figures 1 to 3 were built on unheated substrates to a height of 10 mm using 0.040 mm thick layers for a total of 250 layers in the part. Porosity was measured by optical image analysis at 100x magnification, with Alloy 1 showing less than 0.2% porosity.

[0022] PBF parts are preferably heat-treated after construction to achieve relatively high hardness, strength, and ductility. Achieving high hardness in situ in crack-free constructed parts is relatively difficult due to thermal stresses and thermal fatigue within the parts as they are constructed, coupled with the typically low toughness and ductility of high-hardness alloys. PBF uses an energy source to selectively melt powder in a powder layer, creating a small, rapidly traversing pool of molten metal, which then resolidifies to add the next layer to the part. The heat from the traversing pool is largely conducted into the part, resulting in an increase in temperature throughout the part and providing relatively large temperature gradients in the localized vicinity of the pool. Due to thermal gradients and phase transitions within the part, large continuous and cyclic thermal stresses can develop within the part during construction of the PBF part. Therefore, the part preferably has sufficient strength, toughness, and ductility to resist crack formation under localized stress conditions and crack propagation under continuous and cyclic stresses.

[0023] "As-built" Alloy Properties: Table 2 shows a comparison of the mechanical properties of PBF parts fabricated using commercially available PBF steel alloys in the as-built state (without post-heat treatment) and Alloy 1 (A10) from Table 1. The properties of Alloy 1 (A10) were measured on parts PBF constructed on substrates with no preheat, to a height of 10 mm using 0.040 mm thick layers for a total of 250 layers in the part. Table 2 shows the increased hardness and strength of the metal alloys herein over commercially applied crack-free steel alloys.

[0024] [Table 2]

[0025] With respect to the hardness data in Table 2, it is worth noting that the reported hardness is observed to be a function of the alloy composition as well as the printing procedure employed. Thus, for example, in the case of M300, the printed hardness can vary depending on the printing procedure, such that the HV hardness can be in the range of 320 to 370.

[0026] Table 3 below shows the mechanical properties for all alloys identified in Table 1 in the "AB" or as-built condition without heat treatment, and in the "B1" condition in conjunction with the heat treatment, which is discussed further herein.

[0027] [Table 3]

[0028] Thus, as can be seen from the above, the alloys herein in the as-built state (without heat treatment) are such that they exhibit a tensile strength of at least 1000 MPa, more preferably at least 1100 MPa, or at least 1200 MPa, and even more preferably at least 1300 MPa. Moreover, the tensile strength of the as-built alloys herein can be seen to be in the range of 1000 MPa to 1900 MPa, or 1100 MPa to 1900 MPa, or 1200 MPa to 1900 MPa, or 1300 MPa to 1900 MPa.

[0029] The above tensile strengths are achieved in combination with yield strengths of at least 640 MPa, or at least 700 MPa, or at least 800 MPa, or at least 900 MPa, or at least 1000 MPa, or at least 1100 MPa, or at least 1200 MPa, or at least 1300 MPa, or at least 1400 MPa, or at least 1500 MPa. Furthermore, it can now be appreciated that the yield strengths of the as-built alloys herein are in the range of 640 MPa to 1500 MPa.

[0030] Additionally, the above tensile strengths and yield strengths are also preferably achieved in combination with elongations of at least 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, etc., up to a maximum of 25%. Additionally, it can be appreciated that the elongations of the as-built alloys herein range from 3% to 25%.

[0031] The above tensile strength, yield strength and elongation are then preferably achieved in combination with hardness (HV) values ​​of at least 375, 400, 410, 420, 430, 440, etc., up to a maximum of 600. Furthermore, it can be appreciated that the HV values ​​of the alloys herein are in the range of 375 to 600.

[0032] Accordingly, it should be understood that the alloys herein are such that, in the as-built condition, they are capable of providing a tensile strength of at least 1000 MPa, a yield strength of at least 640 MPa, and an elongation of at least 3% and a hardness (HV) value of at least 375. Other combinations of tensile strength, yield strength, elongation and hardness may be selected from the individual preferred levels of tensile strength, yield strength, elongation and hardness described herein for the unheat treated alloy.

[0033] Figure 4 shows a secondary electron scanning electron microscope (SEM) micrograph at 10,000x magnification of a PBF-fabricated, as-built, Alloy 1 (A10) part. The part shown in Figure 4 was constructed on an unheated substrate to a height of 10 mm using 0.040 mm thick layers for a total of 250 layers in the part. SEM imaging was performed on a Jeol JSM-7001F Field Emission SEM. The microstructure in Figure 4 is expected to include BCC / martensite, FCC, M2CN, and M7C3.

[0034] Figure 5 shows the equilibrium diagram for Alloy 1 (A10) prepared using Thermo-Calc, showing the phase fractions of each thermodynamically stable phase over the temperature range of 20 °C to 1500 °C. The equilibrium diagram was used to identify the phases most likely to contribute to increased hardness and strength.

[0035] The temperature rise of the PBF part during the build, caused by heat transfer from the traversing molten pool to the part, resulted in the formation of Cu-rich FCC phase, M2N ((Cr,Mo)2N) phase, and M, as shown in the phase diagram in Figure 5 for Alloy 1 (A10). 23C6((Cr, Fe, Mo) 23 C6) phase. The in situ precipitation of these phases during part construction is expected to contribute to the strength and hardness of the part in the as-built state.

[0036] "Heat Treatment": PBF parts manufactured using the metal alloys herein can be further strengthened by heat treating to increase the strength and hardness of the part. It is expected that various heat treatments can be performed to affect the part properties, and that the heat treatment temperatures can be selected from an equilibrium phase diagram.

[0037] Effective heat treatments for the metal alloys herein are expected to include (1) high temperature solutionizing (dissolving one or more secondary phases), quenching, and tempering (precipitation of secondary phases), and / or (2) tempering of the as-built component, with each heat treatment step performed in a vacuum, argon, or nitrogen atmosphere. Solutionizing is preferably performed at temperatures above 900°C, e.g., in the range of 900°C to 1400°C, and tempering is preferably performed at temperatures in the range of 150 to 900°C.

[0038] (1) The high-temperature solution treatment and quenching steps are a. Reducing anisotropy within the part that can result from the PBF process; b. Increasing the martensite content and thus the hardness and possibly strength; c. Dissolving Cr carbides and / or Cr nitrides, which may adversely affect the corrosion resistance of the component; d. It is possible to coarsen insoluble carbides and / or nitrides. (2) Further strengthening and hardening of the part through additional precipitation of various phases is expected to be initiated by a subsequent tempering treatment.

[0039] "Heat Treatment" - Procedure: The equilibrium phase diagram in Figure 5 was used to select the solution and tempering temperatures for the PBF parts from Alloy 1 (A10). The heat treatment used for the PBF parts of Alloy 1 (A10) consisted of solutionizing at 1000°C for 1.5 hours, followed by gas quenching at -84°C for 2 hours, and finally tempering in argon at 454°C for 48 hours to strengthen and harden the parts.

[0040] "Heat Treatment" - Alloy Properties: The properties of heat-treated PBF Alloy 1 (A10) parts are shown in Table 4 along with commercially available PBF steel alloys after being subjected to their manufacturer-specified heat treatments for the PBF parts. The properties of heat-treated Alloys 1, 4, 5, 6, 7, 9, 0, 10, and 11 are also listed in Table 3. Alloy 1 (A10) properties were measured on heat-treated parts PBF constructed on substrates without preheat, to a height of 10 mm, using 0.040 mm thick layers for a total of 250 layers in the part. The hardness of Alloy 1 (A10) shown in Table 4 was taken on the surface of the heat-treated parts.

[0041] [Table 4]

[0042] Thus, as can be seen from Tables 3 and 4, the alloys herein after heat treatment are such that they exhibit a tensile strength of at least 1000 MPa, or at least 1100 MPa, or at least 1200 MPa, or at least 1300 MPa, or at least 1400 MPa, or at least 1500 MPa, or at least 1600 MPa, or at least 1700 MPa, or at least 1800 MPa. Furthermore, the heat treated alloys can be understood to have a tensile strength in the range of 1000 MPa to 1900 MPa.

[0043] Such tensile strength is achieved in combination with a yield strength of at least 900 MPa, or at least 1000 MPa, or at least 1100 MPa, or at least 1200 MPa, or at least 1300 MPa, or at least 1400 MPa, or at least 1500 MPa, or at least 1600 MPa. Furthermore, the heat treated alloys herein can be understood to have a yield strength in the range of 900 MPa to 1600 MPa.

[0044] Such tensile strength and yield strength are also achieved in combination with elongation of at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc., up to 16%. Additionally, the heat treated alloys herein can be understood to have elongation values ​​ranging from 1% to 16%.

[0045] Such tensile strength, yield strength and elongation are then preferably achieved in combination with a hardness (HV) value of at least 475, or at least 500, or at least 525, or at least 550, or at least 600. Furthermore, the heat treated alloys herein can be understood to have HV values ​​ranging from 475 to 650.

[0046] It will thus be appreciated that the heat treated alloys of the present invention are such as to provide, for example, a tensile strength of at least 1000 MPa, a yield strength of at least 900 MPa, an elongation of at least 1%, and a hardness (HV) value of at least 475. Other combinations of tensile strength, yield strength, elongation, and hardness may be selected from the individual preferred levels of tensile strength, yield strength, elongation, and hardness mentioned herein for the heat treated alloys.

[0047] Table 4 shows that heat treatment does not increase the hardness of 316L and 17-4PH to a level that would allow either alloy to be classified as a hard alloy (HV > 370). Only the hardness value of M-300 after heat treatment classifies the alloy as a hard alloy (HV > 370), and M300 is currently the primary alloy of choice in additive manufacturing when a hard alloy is required. However, the applicability of M-300 is very limited, as M300 at such hardness levels exhibits only low elongation (2%), indicating a tendency for parts to fracture or chip when subjected to even small impact forces, such as dropping a part to the floor. Therefore, M300 finds relatively limited industrial use.

[0048] Additionally, M300 alloy contains significant concentrations of relatively expensive elements (18 wt.% Ni, 9 wt.% Co, and 5 wt.% Mo), and as such is not considered a low-cost alloy, further limiting its industrial applications. Finally, the industrial use of M-300 is further limited due to its potential EH&S and product control risks posed by its high cobalt content. Cobalt is known for its inhalation health risks and for its control risk due to its classification as a conflict mineral, as it is primarily sourced from the Republic of the Congo.

[0049] In contrast, heat-treated Alloy 1 (A10) has numerous advantages over the currently available M300: it has higher hardness, higher elongation, a lower cost construction, and is preferably cobalt-free.

[0050] Case Hardening Treatment—The surface hardness of PBF parts manufactured using the metal alloys herein can be further enhanced by carburizing and nitriding case hardening treatments. These treatments introduce carbon and nitrogen, respectively, to the surface of the part, creating a case layer with increased hardness compared to the “as-built” or “heat-treated” state while retaining the heat-treated properties in the core. It is anticipated that other treatments employed for surface effects, such as carbonitriding, may also be used.

[0051] Carburizing - The carburizing process for the metal alloys herein preferably comprises a combination of the following steps: oxide reduction, carburizing, solutionizing, quenching, and tempering. Oxide reduction is carried out in a reducing atmosphere, preferably at temperatures of 800°C to 1200°C, more preferably 900°C to 1150°C, and most preferably 950°C to 1100°C. Carburizing is carried out by methods that provide or generate a source of carbon in the atmosphere or environment surrounding the part, such as pack carburizing, gas carburizing, vacuum carburizing, liquid carburizing, and plasma carburizing, preferably at temperatures of 800°C to 1000°C, more preferably 850°C to 975°C, and most preferably 875°C to 950°C.

[0052] Carburizing results in carbon enrichment at the surface of the part, resulting in a layer of material with a different microstructure compared to the core, as seen at two different magnifications in Figure 6 for Alloy 5. This structure results in a maximum hardness at the outer surface that is preferably 650 to 1000 HV, more preferably 700 to 975 HV, and most preferably 800 to 950 HV. The hardness then gradually decreases with increasing distance from the outer surface (i.e., depth into the part) until it reaches a steady-state value in the core that is similar to the heat-treated values ​​discussed herein. Representative examples of hardness as a function of depth for carburized case-hardened Alloys 5 and 8 are shown in Figure 7. Other alloys listed herein can also be case-hardened by the carburizing process with similar effects. Carbon levels can increase at the surface to a depth of at least 2.0 mm and up to 4.0 mm.

[0053] Nitriding—The nitriding process for the metal alloys herein involves a combination of the following steps: solutionizing, quenching, and tempering. It is anticipated that nitrogen can be introduced to the surface of a component by other nitriding methods, including plasma nitriding and liquid nitriding processes. Nitrogen enrichment at the surface of a component results in a layer of material with a different microstructure compared to the core, as can be seen in the two different magnifications for Alloy 9 (Table 1) shown in Figure 8. This structure results in a maximum hardness at the outer surface, preferably 700 to 1300 HV, more preferably 750 to 1250 HV, and most preferably 825 to 1225 HV. The hardness then gradually decreases with increasing distance from the outer surface (i.e., depth into the component) until it reaches a steady-state value in the core that is similar to the heat-treated values ​​discussed herein. A representative example of hardness as a function of depth for nitride-surface-hardened Alloys 8 and 9 is seen in Figure 9. As can be seen, the level of nitrogen is increased from the surface to a depth of at least 200 μm and up to 400 μm. Other alloys listed herein can similarly be case hardened by a nitriding process with similar effect. This disclosure is based on the following <1> ~ <22> The following aspects are also included. <1> 1. A method for layer-by-layer construction of a metal part, comprising: providing an iron-based alloy in particulate form comprising the elements Cr and Mo and at least three elements from the group consisting of C, Ni, Cu, Nb, Si and N, wherein Cr is present at 10.0 wt.% to 19.0 wt.%, Mo is present at 0.5 wt.% to 3.0 wt.%, C is present at 0 to 0.35 wt.%, Ni is present at 0 to 5.0 wt.%, Cu is present at 0 to 5.0 wt.%, Nb is present at 0 to 1.0 wt.%, Si is present at 0 to 1.0 wt.%, and N is present at 0 to 0.25 wt.%, with the remainder of the alloy composition comprising Fe; forming one or more layers of the alloy by melting the alloy to a molten state and cooling to form solidified layers of the elements, each solid layer having a thickness comprised between 2.0 microns and 200.0 microns; The method, wherein the metal part has the following properties: tensile strength of at least 1000 MPa, yield strength of at least 640 MPa, elongation of at least 3.0%, hardness (HV) of at least 375. <2> Cr is present at 10.0 wt.% to 18.3 wt.%, Mo is present at 0.5 wt.% to 2.5 wt.%, C is present at 0 to 0.30 wt.%, Ni is present at 0 to 4.0 wt.%, Cu is present at 0 to 4.0 wt.%, Nb is present at 0 to 0.7 wt.%, Si is present at 0 to 0.7 wt.%, and N is present at 0 to 0.25 wt.%, with the remainder being Fe; <1> The method described below. <3> The alloy comprises 82.0 wt.% to 86.0 wt.% Fe, 10.5 wt.% to 12.0 wt.% Cr; 1.5 wt.% to 2.5 wt.% Ni; 0.4 wt.% to 0.7 wt.% Cu; 1.2 wt.% to 1.8 wt.% Mo; 0.14 wt.% to 0.18 wt.% C; 0.02 wt.% to 0.05 wt.% Nb; 0.04 to 0.07 wt.% N and 0 to 1.0 wt.% Si. <1> The method described below. <4> The metal part has the following properties: a tensile strength of 1000 MPa to 1900 MPa, a yield strength of 640 MPa to 1500 MPa, an elongation of 3.0% to 25.0%, and a hardness (HV) of 375 to 600. <1> The method described below. <5> the layer having a thickness of 2.0 microns to 200 microns; <1> The method described below. <6> Melting point: 30J / mm 3 to 500J / mm 3 This is achieved by a laser beam or electron beam having an energy density in the range of <1> The method described below. <7> The metal parts are constructed in a nitrogen and / or argon atmosphere; <1> The method described below. <8> The metal part is constructed on a substrate that is preheated to a temperature of 300°C or less. <1> The method described below. <9> The metal part is subjected to solution treatment at a temperature exceeding 900°C followed by gas quenching. <1> The method described below. <10> After cooling, the metal part is tempered at a temperature of 150°C or higher. <9> The method described below. <11> After tempering, the metal part exhibits a tensile strength of at least 1000 MPa, a yield strength of at least 900 MPa, an elongation of at least 1.0%, and a hardness (HV) of at least 475. <10> The method described below. <12> The metal part is carburized to increase the level of carbon from the surface to a depth of 4.0 mm. <1> The method described below. <13> The metal part is nitrided to increase the level of nitrogen from the surface to a depth of 400 μm. <1> The method described below. <14> The alloy comprises at least four elements selected from C, Ni, Cu, Nb, Si and N; <1> The method described below. <15> The alloy comprises at least five elements selected from C, Ni, Cu, Nb, Si and N; <1> The method described below. <16> The alloy comprises C, Ni, Cu, Nb, Si and N; <1> The method described below. <17> 1. A 3D printed metal part comprising one or more iron-based alloy layers comprising the elements Cr and Mo and at least three elements from C, Ni, Cu, Nb, Si, and N, wherein Cr is present at 10.0 wt.% to 19.0 wt.%, Mo is present at 0.5 wt.% to 3.0 wt.%, C is present at 0 to 0.35 wt.%, Ni is present at 0 to 5.0 wt.%, Cu is present at 0 to 5.0 wt.%, Nb is present at 0 to 1.0 wt.%, Si is present at 0 to 1.0 wt.%, and N is present at 0 to 0.25 wt.%, with the remainder of the alloy composition comprising Fe; the layer has a thickness ranging from 2.0 microns to 200.0 microns; The printed metal part exhibits a tensile strength of at least 1000 MPa, a yield strength of at least 640 MPa, an elongation of at least 3.0%, and a hardness (HV) of at least 375. <18> Cr is present at 10.0 wt.% to 18.3 wt.%, Mo is present at 0.5 wt.% to 2.5 wt.%, C is present at 0 to 0.30 wt.%, Ni is present at 0 to 4.0 wt.%, Cu is present at 0 to 3.5 wt.%, Nb is present at 0 to 0.7 wt.%, Si is present at 0 to 0.7 wt.%, and N is present at 0 to 0.25 wt.%, with the balance being Fe; <17> 10. The printed metal part according to claim 1 . <19> The alloy comprises at least four elements selected from C, Ni, Cu, Nb, Si and N; <17> 10. The printed metal part according to claim 1 . <20> The alloy comprises at least five elements selected from C, Ni, Cu, Nb, Si and N; <17> 10. The printed metal part according to claim 1 . <21> The alloy comprises C, Ni, Cu, Nb, Si and N, <17> 10. The printed metal part according to claim 1 . <22> The part exhibits a tensile strength of 1000 MPa to 1900 MPa, a yield strength of 640 MPa to 1500 MPa, an elongation of 3.0% to 25.0%, and a hardness (HV) of 375 to 600. <17> 10. The printed metal part according to claim 1 .

Claims

1. An iron-based alloy for 3D printing of metal parts, comprising the elements C, Cr and Mo and at least two elements selected from the group consisting of Ni, Cu, Nb, Si and N, C is present at 0.1 wt. % to 0.30 wt. %; Cr is present at 10.0 wt.% to 12.0 wt.%; Mo is present at 0.89 wt.% to 3.0 wt.%; Ni is present at 0 to 5.0 wt. %; Cu is present at 0 to 5.0 wt. %; Nb is present at 0 to 1.0 wt. %; Si is present at 0 to 1.0 wt. %, and N is present at 0 to 0.25 wt. %; the remainder of the alloy composition being Fe; The alloy is used in powder form for 3D printing of metal parts. Iron-based alloy for 3D printing of metal parts.

2. C is present at 0.1 wt. % to 0.30 wt. %; Cr is present at 10.0 wt.% to 12.0 wt.%; Mo is present at 0.89 wt.% to 2.5 wt.%; Ni is present at 0 to 4.0 wt. %; Cu is present at 0 to 4.0 wt. %; Nb is present at 0 to 0.7 wt. %; Si is present in an amount of 0 to 0.7 wt. %, and N is present at 0 to 0.25 wt. %; 10. The alloy of claim 1.

3. 10. The alloy of claim 1, wherein Cr is present at 10.5 wt.% to 12.0 wt.%.

4. 10. The alloy of claim 1, wherein C is present at 0.1 wt.% to 0.25 wt.%.

5. 10. The alloy of claim 1, comprising at least three elements selected from the group consisting of Ni, Cu, Nb, Si, and N.

6. 10. The alloy of claim 1 comprising at least four elements selected from the group consisting of Ni, Cu, Nb, Si, and N.

7. 10. The alloy of claim 1 comprising Ni, Cu, Nb, Si, and N.

8. 10. The alloy of claim 1, wherein the metal component has the following properties: tensile strength equal to or greater than 1000 MPa, yield strength equal to or greater than 640 MPa, elongation equal to or greater than 1.0%, and hardness (HV) equal to or greater than 375.

9. 10. The alloy of claim 1, wherein the metal component has the following properties: tensile strength from 1000 MPa to 1900 MPa, yield strength from 640 MPa to 1500 MPa, elongation from 1.0% to 25.0%, and hardness (HV) from 375 to 600.

10. 10. The alloy of claim 1, exhibiting a tensile strength of 1000 MPa or greater, a yield strength of 900 MPa or greater, an elongation of 1.0% or greater, and a hardness (HV) of 475 or greater.

11. 10. The alloy of claim 1, wherein said powder form of the alloy comprises particles having diameters in the range of 1 to 200 microns.

12. 10. The alloy of claim 1, wherein said powder form of the alloy comprises particles having diameters ranging from 3 to 70 microns.

13. 2. The method of claim 1, comprising producing the alloy in powder form by atomization. A method for manufacturing the alloy.

14. The method of claim 13 , wherein the atomization comprises at least one of gas atomization and water atomization.

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