Alloy member and method for producing alloy member

Abstract

To provide an alloy member and a method for manufacturing the alloy member, which make use of the excellent characteristics of a multicomponent alloy composed of a high-entropy alloy (HEA) or composed of four or more elements while accommodating diversification of usage environments.SOLUTION: An alloy member includes, at least partially, a first alloy and a second alloy differing in composition from the first alloy, wherein the first alloy and the second alloy are arranged in a continuous and integral manner; the first alloy has, on its surface, a hardened layer composed of a nitride; the second alloy contains each element of Co, Cr, Fe, Ni, and Ti in the range of 1 atom% or more to 35 atom% or less, and further contains Mo in the range of more than 0 atom% and 8 atom% or less, B in an amount of 0.15% or less, and either or both of Nb and Ta in an amount of 10.0% or less; and the hardness of the hardened layer is 1.2 times or more than the surface hardness of the second alloy.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an alloy member and a method for manufacturing the alloy member.

Background Art

[0002] In recent years, as an alloy with a new technical concept that is distinct from the technical concept of conventional alloys (for example, an alloy in which a plurality of sub-component elements are added in trace amounts to one to three main component elements), a high entropy alloy (High Entropy Alloy: HEA) has been proposed.

[0003] (a) Stabilization of the mixed state due to a negative increase in the mixing entropy term in the Gibbs free energy formula, (b) Diffusion delay due to a complex microstructure, (c) Hardening due to high lattice strain caused by the size difference of constituent atoms and a decrease in the temperature dependence of mechanical properties, (d) Improvement in corrosion resistance due to the complex influence (also referred to as the cocktail effect) caused by the coexistence of multiple elements, etc. can be cited as the features of HEA.

[0004] Here, Patent Document 1 discloses an alloy member having a chemical composition containing each of the elements Co, Cr, Fe, Ni, and Ti in the range of 5 atomic% or more and 35 atomic% or less, and containing Mo in the range of more than 0 atomic% and 8 atomic% or less, with the balance consisting of unavoidable impurities, and in which extremely small particles with an average particle size of 100 nm or less are dispersed and precipitated in the matrix crystal grains.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] According to the technology related to Patent Document 1, an alloy member excellent in mechanical properties such as tensile strength and ductility and corrosion resistance can be obtained. However, it has been difficult to cope with the diversification and severity of the use environment only with the configuration of such an alloy member.

[0007] From the above, an object of the present invention is to provide an alloy member and a method for manufacturing the alloy member that can cope with the diversification of the use environment and the like while taking advantage of the excellent characteristics of HEA and multi-component alloys composed of four or more elements.

Means for Solving the Problems

[0008] The alloy member of the present invention includes at least a part of a first alloy and a second alloy having a composition different from that of the first alloy, and the first alloy and the second alloy are arranged continuously and integrally. The first alloy has a hardened layer composed of a nitride on its surface, and the second alloy contains each of the elements Co, Cr, Fe, Ni, and Ti in a range of 1 atomic % or more and 35 atomic % or less, and contains Mo in a range of more than 0 atomic % and 8 atomic % or less, contains B at 0.15% or less, and contains either one or both of Nb and Ta at 10.0% or less. The hardness of the hardened layer is 1.2 times or more the hardness of the surface of the second alloy. It is an alloy member characterized by this.

[0009] Also, an embodiment of the present invention includes at least a part of a first alloy and a second alloy having a composition different from that of the first alloy, and the first alloy and the second alloy are arranged continuously and integrally. The first alloy has a hardened layer composed of a nitride on its surface, and the second alloy contains each of the elements Co, Cr, Fe, Ni, and Ti in a range of 5 atomic % or more and 35 atomic % or less, and contains Mo in a range of more than 0 atomic % and 8 atomic % or less, and the balance consists of inevitable impurities. One of the features is that the hardness of the hardened layer is 1.2 times or more the hardness of the surface of the second alloy.

[0010] Furthermore, it preferably contains B at 0.15% or less and contains either one or both of Nb and Ta at 10.0% or less.

[0011] The present invention also includes a shaping step of injecting a second alloy powder having a composition different from that of the first alloy onto the first alloy, irradiating the second alloy powder with a heat source to melt and solidify the second alloy powder onto the first alloy to obtain an alloy member, and a surface treatment step of forming a hardened layer on the surface of the first alloy of the alloy member. The second alloy contains each of the elements Co, Cr, Fe, Ni, and Ti in the range of 1 atomic % or more and 35 atomic % or less, contains Mo in the range of more than 0 atomic % and 8 atomic % or less, contains B at 0.15% or less, and contains one or both of Ta and Nb at 10.0% or less. It is a method for manufacturing an alloy member characterized by this.

[0012] The present invention also includes a shaping step of injecting a second alloy powder having a composition different from that of the first alloy onto the first alloy, irradiating the second alloy powder with a heat source to melt and solidify the second alloy powder onto the first alloy to obtain an alloy member, and a surface treatment step of forming a hardened layer on the surface of the first alloy of the alloy member. The second alloy contains each of the elements Co, Cr, Fe, Ni, and Ti in the range of 5 atomic % or more and 35 atomic % or less, contains Mo in the range of more than 0 atomic % and 8 atomic % or less, and the balance consists of unavoidable impurities. It is a method for manufacturing an alloy member characterized by this.

Effects of the Invention

[0013] According to the present invention, while making use of the excellent properties of HEAs and multi-component alloys composed of four or more elements, it is possible to provide an alloy member and a method for manufacturing an alloy member that can cope with diversification of the usage environment and the like.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0015] The first embodiment of the alloy member of the present invention includes at least a part of a first alloy and a second alloy having a composition different from that of the first alloy, and the first alloy and the second alloy are continuously and integrally arranged. The first alloy has a hardened layer composed of a nitride on its surface. The second alloy contains each element of Co, Cr, Fe, Ni, and Ti in the range of 1 atomic % or more and 35 atomic % or less, contains Mo in the range of more than 0 atomic % and 8 atomic % or less, contains B at 0.15% or less, and contains either one or both of Nb and Ta at 10.0% or less. One of the features is that the hardness of the hardened layer is 1.2 times or more the hardness of the surface of the second alloy. Hereinafter, an embodiment of the alloy member will be described with reference to FIG. 1. However, the present invention is not limited to the embodiments cited here, and appropriate combinations and improvements are possible without departing from the technical idea of the invention.

[0016] Details of the chemical composition and content of the alloy member will be described. Hereinafter, when simply described as %, it refers to mass %. Also, a numerical range represented using "~" means including the numerical values described before and after "~" as the lower limit value and the upper limit value. The upper limit value and the lower limit value described before and after "~" can be arbitrarily combined.

[0017] An embodiment of the alloy member will be described by taking as an example the case where it is manufactured using an additive manufacturing method. Figure 1 shows a schematic cross-sectional view of the alloy member. As shown in Figure 1, the alloy member 40 includes a first alloy 50, a hardened layer 60, and a second alloy 70. Also, the first alloy and the second alloy are arranged continuously and integrally, and the hardened layer 60 is provided on at least a part of the first alloy 50. In other words, the second alloy 70 does not have the hardened layer 60 or has an extremely thin layer thickness compared to the hardened layer 60 formed on the first alloy 50. Here, being arranged continuously and integrally means that at least a part of the first alloy and at least a part of the second alloy may be in a state where they are heated and integrally joined by melting and solidification. Furthermore, in addition to being integrally joined by melting and solidification, the first alloy and the second alloy may be joined in a state where they are combined with a state of being joined using a fastening member.

[0018] (First alloy) The first alloy 50 is not particularly limited, and various metal materials can be used. For example, Fe-based alloys, Ni-based alloys, Ti-based alloys, Co-based alloys, and cemented carbides. More specifically, alloy tool steels for hot die used in die casting, etc., alloy tool steels for cold die used in press forming, high-speed tool steels used in cutting, etc., alloy for extrusion die used in extrusion forming, steel for plastic die used in plastic forming, general steel, stainless steel, wear-resistant alloys, etc. can be used. Also, the first alloy 50 may include those in a state where two or more alloys are joined in advance. For example, it may be an integrated one formed by welding an alloy different from the base alloy on the base alloy.

[0019] More specifically, steel types such as SKD61, maraging steel, SKD11, SKH51, SCM440, S50C, SUS316L, Alloy718, Stellite 6 (registered trademark of Kennametal Incorporated) can be mentioned.

[0020] (Second alloy) The second alloy 70 can use, for example, a high entropy alloy (HEA) which is an alloy with a new technical concept that is distinct from the technical concept of an alloy in which a plurality of sub-component elements are added in trace amounts to one to three main component elements, or a multi-component alloy composed of four or more elements. HEA is defined as an alloy composed of five or more main metal elements (each 5 to 35 atomic %), which has excellent mechanical properties and corrosion resistance, and further has improved hardness and wear resistance.

[0021] In addition, although the alloy concept of a multi-principal element alloy (MPEA) having a plurality of main elements but allowing the existence of multiple phases has been proposed, in this application, HEA and MPEA are treated as the same concept, and both are collectively referred to as HEA.

[0022] The second alloy, for example, contains five elements Co, Cr, Fe, Ni, and Ti as main components in the range of 5 atomic % or more and 35 atomic % or less respectively, contains Mo as a sub-component in the range of more than 0 atomic % and 8 atomic % or less, contains B at 0.15% or less, and contains either one or both of Ta and Nb at 10.0 atomic % or less. Also, it is an alloy containing five elements Co, Cr, Fe, Ni, and Ti as main components in the range of 5 atomic % to 35 atomic % respectively, contains Mo as a sub-component in the range of more than 0 atomic % and 8 atomic % or less, contains B at 0.15% or less, contains either one or both of Ta and Nb at 10.0 atomic % or less, and the balance consists of inevitable impurities.

[0023] Also, the second alloy may contain five elements Co, Cr, Fe, Ni, and Ti at 1 atomic % or more and 35 atomic % or less respectively, Mo at more than 0 atomic % and 8 atomic % or less, and B at 0.15% or less.

[0024] Also, the second alloy may contain Co at 20 atomic % to 35 atomic %, Cr at 10 atomic % to 25 atomic %, Fe at 10 atomic % to 25 atomic %, Ni at 15 atomic % to 30 atomic %, Ti at 2.5 atomic % to 15 atomic %, and B at more than 0 atomic % and 0.15% or less.

[0025] In addition, the second alloy may contain Co at 25 atomic % to 33 atomic %, Cr at 15 atomic % to 23 atomic %, Fe at 15 atomic % to 23 atomic %, Ni at 17 atomic % to 28 atomic %, Ti at 3.0 atomic % to 10 atomic %, Mo at 1 atomic % to 7 atomic %, and B in an amount exceeding 0 atomic % and 0.1% or less.

[0026] In addition, the second alloy may contain Co in an amount of 25 atomic % or more and less than 30 atomic %, Cr in an amount of 15 atomic % or more and less than 20 atomic %, Fe in an amount of 15 atomic % or more and less than 20 atomic %, Ni in an amount of 23 atomic % to 28 atomic %, Ti in an amount of 7 atomic % to 10 atomic %, Mo in an amount of 1 atomic % or more and 7 atomic % or less, and B in an amount exceeding 0 atomic % and 0.1% or less. By controlling the composition within these ranges, it is even more effective in achieving both improved ductility and improved tensile strength.

[0027] Furthermore, the second alloy may contain one of Ta and Nb in an amount of 5.0 atomic % or less, preferably 1.0 atomic % to 5.0 atomic %, and more preferably 2.0 atomic % to 4.0 atomic %. When both Ta and Nb are contained, the total is preferably 10.0 atomic % or less, and more preferably 8.0 atomic % or less.

[0028] (Hardened layer) The first alloy 50 has a hardened layer 60 formed of nitrides and carbides on its surface. The hardened layer 60 is formed by allowing nitrogen and carbon to penetrate and diffuse into the surface of the first alloy. The hardness ratio (H1 / H2) of the hardness H1 of the hardened layer 60 of the first alloy 50 to the hardness H2 of the surface of the second alloy 70 is 1.2 times or more, and preferably 1.5 times or more.

[0029] (Hardness) The hardness can be measured by a Vickers hardness tester at room temperature with a load of 0.1 kgf and a holding time of 10 seconds. The measurement can be performed three times, and the average value can be recorded.

[0030] In the case of the alloy member of the present embodiment, since the first alloy having a hardened layer and the second alloy are continuously and integrally arranged, this alloy member is excellent in mechanical properties and hardness, and has corrosion resistance in a harsh environment. That is, an alloy member capable of selectively imparting characteristics can be provided.

[0031] <Manufacturing method of alloy member> Next, an embodiment of the manufacturing method of the alloy member will be described with reference to FIGS. 2 and 3. As shown in FIG. 2(a), an embodiment of the manufacturing method of the alloy member includes a shaping step (S101) of injecting a second alloy powder having a composition different from that of the first alloy powder onto the first alloy and irradiating the second alloy powder with a heat source to melt and solidify the second alloy powder onto the first alloy to obtain an alloy member, and a surface treatment step (S103) of forming a hardened layer on the surface of the first alloy among the alloy members. The second alloy contains each element of Co, Cr, Fe, Ni, and Ti in the range of 1 atomic % to 35 atomic % respectively, contains Mo in the range of more than 0 atomic % and 8 atomic % or less, contains B at 0.15% or less, and contains one or both of Ta and Nb at 10.0% or less as one of the features. Hereinafter, the embodiments of the present invention will be described more specifically for each step. In some cases, an alloy member manufactured by an additive manufacturing method may be referred to as an additive manufactured product.

[0032] (Shaping step) As an embodiment of the shaping step of performing shaping by irradiating an alloy powder with an electron beam or a laser beam and melting and solidifying it, either a powder bed fusion (PBF) method or a directed energy deposition (DED) method, which is an additive manufacturing method for metal materials, can be applied.

[0033] For example, by repeatedly performing a melting and solidification step of irradiating an alloy powder with a heat source such as an electron beam or a laser beam to melt and solidify it to form a solidified layer, a solidified layer can be further laminated on the solidified layer to manufacture the alloy member of the present embodiment. Also, for example, in the directed energy deposition method, alloy powder is sprayed while moving it onto a substrate, and a melting and solidification process of irradiating the sprayed alloy powder with an electron beam or a laser beam to melt and solidify it to form a solidified layer is repeated, and a solidified layer is further laminated on the solidified layer, whereby the alloy member (formed body) of the present embodiment can be obtained.

[0034] Further, in accordance with the method of the additive manufacturing method, the powder particle size may be adjusted by sieving classification using a mesh, air classification, or the like.

[0035] For example, when applying to the powder bed fusion bonding method, it is preferable to adjust the average particle size (D50) of the alloy powder to be in the range of 10 to 53 μm. Also, for example, the metal powder used in the directed energy deposition method preferably removes coarse powder that is difficult to melt in order to melt the powder with a laser beam serving as a heat source.

[0036] Also, it is preferable to remove fine powder for the purpose of preventing dust scattering when supplying the powder to the heat source and ensuring fluidity that enables easy conveyance of the powder. Therefore, when applying the shaping powder of the present embodiment to the directed energy deposition method, it is preferable to adjust D50 to be in the range of 53 to 106 μm. On the other hand, when using an electron beam or plasma as the heat source, since it becomes possible to perform shaping using coarser metal particles, D50 is preferably set to 75 to 250 μm.

[0037] Fig. 3 shows a schematic configuration of an additive manufacturing apparatus 1 that performs additive manufacturing using a laser beam as a heat source in a directed energy deposition method. The additive manufacturing apparatus 1 mainly includes a powder supply nozzle 3, a focusing lens 5, a protective lens 7, etc. Alloy powder 11 is supplied to the powder supply nozzle 3 and ejected from the tip of the powder supply nozzle 3 together with argon gas. A laser beam 9 emitted from a laser oscillator (not shown) is focused by the focusing lens 5 and irradiated near the tip of the powder supply nozzle 3. A protective lens 7 is provided below the focusing lens 5.

[0038] In the additive manufacturing method, while supplying the alloy powder 11 onto the base material 17, the powder supply nozzle 3 is relatively moved with respect to the base material 17 (in the A direction in Fig. 3). At this time, the alloy powder 11 supplied is irradiated with the laser beam 9 focused by the focusing lens 5, and a molten pool in which the alloy powder 11 is melted is formed and solidified, thereby forming a formed body 15 (alloy member). This process is repeated using a program file created using CAD-CAM software, and by laminating the formed body 15 on the base material 17, a three-dimensional alloy member having at least a part of a second alloy is formed. Note that the alloy constituting the base material and / or an alloy different from the base material continuously and integrally formed on the base material may be referred to as the first alloy.

[0039] In the directed energy deposition method, using a three-dimensional additive manufacturing apparatus, the surface of a base material such as a formed body or a mold is rapidly melted by laser irradiation, raw material powder is supplied into the formed molten pool, and rapid solidification is performed. A formed body (alloy member) is produced by repeatedly laminating a series of processes. The formed body formed on the base material is the alloy member of this embodiment. Also, in the case of repairing a mold, a manufactured product can be obtained. The additive manufacturing conditions are appropriately determined in consideration of the particle size and composition of the raw material powder, the size, shape, characteristics, and production efficiency of the formed body, etc. For the alloy of this embodiment, for example, it can be selected from the following ranges. Hereinafter, the alloy constituting the base material will be described as the first alloy, and the raw material powder or the raw material powder rapidly solidified will be described as the second alloy.

[0040] The layer thickness during additive manufacturing is, for example, 0.1 mm to 2.0 mm, preferably 0.4 to 1.5 mm. The total thickness of all layers from the interface of the substrate to the surface of the second alloy is preferably 0.1 mm to 5 mm in order to suppress the peeling of the second alloy from the first alloy and the cracking of the second alloy.

[0041] Next, the laser beam diameter is preferably set in the range of 0.5 to 3 mm at the irradiated position. The laser output is preferably 1500 to 2500 W. The laser scanning speed is preferably 200 to 3000 mm / min, more preferably 1000 to 2000 mm / min. The powder supply rate is preferably 10 to 20 g / min.

[0042] When irradiating a heat source such as a laser to melt the raw material powder, the density of the input energy (energy density of the heat source: J / mm) is preferably 90 to 300 J / mm, and the range of 180 to 240 J / mm is more preferable. By setting the energy density in the range of 90 to 300 J / mm, an increase in the defect rate can be suppressed, and furthermore, the supplied powder becomes difficult to melt. When centered on the laser irradiation position, melting of the first alloy or the shaped body itself can also be prevented, and the shape of the shaped body is easily maintained. The energy density of the heat source can be obtained by E = P / v × 60 using the laser output P (W) and the laser scanning speed v (mm / min).

[0043] [Alloy powder] As the alloy powder serving as the raw material for the second alloy, for example, as described above, it contains, as main components, 5 elements of Co, Cr, Fe, Ni, and Ti in the range of 5 atomic % or more and 35 atomic % or less respectively, contains Mo as a sub-component in the range of more than 0 atomic % and 8 atomic % or less, contains B at 0.15% or less, and contains either one or both of Ta and Nb at 10.0 atomic % or less. An alloy powder can be used. Also, as main components, it contains 5 elements of Co, Cr, Fe, Ni, and Ti in the range of 5 atomic % to 35 atomic % respectively, contains Mo as a sub-component in the range of more than 0 atomic % and 8 atomic % or less, contains B at 0.15% or less, contains either one or both of Ta and Nb at 10.0 atomic % or less, and the balance consists of inevitable impurities. An alloy powder can be used.

[0044] The alloy powder used as the raw material can be obtained, for example, by an atomization method. There is no particular limitation on the atomization method, and conventional methods can be used. For example, gas atomization methods (such as vacuum gas atomization method, electrode induction melting type gas atomization method, etc.), centrifugal atomization methods (such as disk atomization method, plasma rotating electrode atomization method, etc.), plasma atomization method, etc. are preferable.

[0045] (Surface treatment process) The surface treatment process is a process of performing surface treatment on the alloy member. From the viewpoint of improving the hardness of the alloy member, methods such as nitriding treatment or carburizing treatment that diffuse nitrogen or carbon can be preferably used. The surface treatment may be performed on the surface of the alloy member in a state where the first alloy and the second alloy are exposed. Also, the surface treatment may be performed in a state where the first alloy and the second alloy are continuously integrated. And, as described later, the surface treatment process may also serve as an aging heat treatment process by maintaining the surface treatment temperature in the surface treatment process, for example, at 450°C or more and less than 1000°C, preferably more than 500°C and 900°C or less, and performing the surface treatment. By overlapping the surface treatment temperature of the surface treatment process with the range of the aging heat treatment temperature, it is possible to improve the hardness of the second alloy in addition to improving the hardness of the first alloy by the surface treatment. And, it is expected that the manufacturing process can be simplified by the surface treatment process also serving as an aging heat treatment.

[0046] [Nitriding treatment] As an example of the surface treatment process, nitriding treatment for diffusing nitrogen into the surface of an alloy member will be described. In nitriding treatment, nitrogen is introduced into the surface of the alloy member to form a diffusion layer (hardened layer). The thickness of the hardened layer is preferably 5 μm or more. More preferably, it is 50 μm or more. Even more preferably, it is 100 μm or more. The method for forming the hardened layer is not particularly limited, and for example, plasma nitriding, gas nitriding, vacuum gas nitriding, salt bath nitriding, etc. can be used. A compound layer containing nitrogen may be formed on the diffusion layer. It is more preferable to use vacuum gas nitriding.

[0047] The treatment conditions for gas nitriding are not particularly limited. For example, the temperature can be in the range of 400°C to 650°C, the heat treatment time can be in the range of 1 hour to 48 hours, and the atmosphere can be a mixed gas atmosphere containing ammonia gas.

[0048] (Aging heat treatment process) As shown in the flowchart of FIG. 2(b), aging heat treatment (S203) may be performed between the shaping process (S201) and the surface treatment process (S205). The aging heat treatment is preferably an aging heat treatment in which the above alloy member is heated while raising the temperature and held in a temperature range where fine particles are likely to increase, for example, a temperature range of 450°C or more and less than 1000°C, for the purpose of increasing the hardness of the alloy member.

[0049] When the aging heat treatment temperature is 450°C or more, an effect of improving the strength can be obtained, and when it is 900°C or less, the formation of hexagonal precipitates can be suppressed and the ductility can be maintained. Note that the upper limit value and the lower limit value can be arbitrarily combined. The same applies hereinafter. The holding time is preferably 0.5 hour to 24 hours. Preferably, it is set to 0.5 hour to 8 hours, more preferably 1 hour to 8 hours. For the second alloy, when it is 0.5 hour or more, an effect of improving the strength can be obtained, and when it is 24 hours or less, the formation of hexagonal precipitates that cause deterioration of the corrosion resistance can be suppressed. By the above aging heat treatment, nano-scale fine particles with an average particle size of 50 nm or less can be generated in the microcell structure described later, and the strength can be improved.

[0050] By performing aging heat treatment at a temperature equal to or higher than the temperature at which the alloy member is used, an alloy member with little hardness reduction when used in a temperature range lower than that can be obtained. For members that require wear resistance at high temperatures, it is preferable to perform aging heat treatment at a temperature equal to or higher than the practical temperature. In that case, the aging heat treatment temperature is preferably 600°C to 950°C, more preferably 650°C to 900°C.

[0051] Note that depending on the temperature of the aging heat treatment process, the first alloy may soften and its hardness may decrease. In that case, the first alloy may be pre-hardened. By performing the hardening treatment with a higher hardening temperature, the hardness can be improved, and the hardness decrease of the first alloy in the aging heat treatment process can be kept within a practically usable range.

[0052] The cooling method after aging heat treatment is not particularly limited. However, since excessive generation of nano-scale ultrafine particles may occur when holding for a long time near the aging heat treatment temperature, it is good to cool to room temperature by air cooling or gas cooling, etc. Also, the heat treatment pattern can be variously changed. Also, in the heating process of aging heat treatment, for example, if the heating rate is 5°C / min or more, the residence temperature in the intermediate temperature range where it becomes difficult to adjust the precipitation amount can be shortened, so it is preferable, and 10°C / min or more is more preferable. The upper limit of the heating rate in aging heat treatment is not particularly limited, but it is preferably about 1000°C / min or less from the viewpoint of ensuring the temperature uniformity in the alloy member, particularly preventing the occurrence of overheated parts.

[0053] For the alloy member (additive product) produced through the shaping process and the surface treatment process described above, a hardened layer can be formed on the surface of the first alloy among the first alloy and the second alloy constituting the alloy member.

[0054] <Use · Product> The uses and products using the alloy member of the present invention are arbitrary. By appropriately selecting the manufacturing method, such as subjecting the shaped body to aging heat treatment, or subjecting the shaped body to solution heat treatment and aging heat treatment, mechanical properties and wear resistance corresponding to the use can be obtained.

[0055] As an example of the use, it can be applied to oil well drilling devices, screws and cylinders for injection molding, turbine wheels such as those in generators, impellers of compressors, valves and joints in chemical plants, heat exchangers, pumps, semiconductor manufacturing devices and components, casting molds, forging molds, extrusion molds, press molds, plastic molding molds, etc. These machines, devices, components, molds, parts, etc. are collectively referred to as products.

Example

[0056] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. It should be noted that the present invention is not limited to these examples.

[0057] An Fe-based alloy M1 having the alloy composition shown in Table 1 was used as the first alloy M1, and an alloy powder P1 having the alloy composition shown in Table 2 was used as the second alloy. The first alloy M1, which is an Fe-based alloy, is a material equivalent to SKD61. The composition of the alloy powder P1 can be converted to Ni: 23.6%, Cr: 19.6%, Fe: 14.7%, Ti: 8.7%, Mo: 2.3%, B: 0.07% in atomic percentage.

[0058]

Table 1

Table 2

[0059] As the additive manufacturing method, using a three-dimensional additive manufacturing apparatus (LASERTEC65 3D Hybrid manufactured by DMG Mori Seiki Co., Ltd.) of the directed energy deposition (DED) method, the alloy powder P1 was supplied to the molten pool formed by laser irradiation on the first alloy M1, and it was rapidly melted and rapidly solidified to produce a shaped body F1 with a width of 15 mm, a length of 15 mm, and a stacking height of about 5 mm. The additive manufacturing conditions were as follows.

[0060] · Thickness of one layer during additive manufacturing: 0.92 mm · Laser beam diameter: about 3 mm · Laser output: 2400 W · Laser scanning speed: 1000 mm / min

[0061] Next, an alloy member FA1 having a hardened layer 60 formed on the surface of the shaped body F1 was produced using the vacuum gas nitriding method. Here, in FIGS. 3 to 6 and the following description, the alloy member FA1 will be described as an alloy member 40, the first alloy 50 as a first alloy M1, and the portion shaped using the alloy powder P1 as a second alloy 70.

[0062] FIG. 4 shows a cross-sectional photograph when the alloy member 40 is viewed perpendicularly to the stacking direction Z. The broken line in FIG. 4 indicates the boundary between the first alloy M1 and the hardened layer 60 and the second alloy 70. FIG. 5 shows a backscattered electron image taken using a scanning electron microscope (JSM-7001F, manufactured by JEOL Ltd.) of an arbitrary cross-section of the alloy member 40. FIG. 5(a) shows a backscattered electron image of the cross-section of the first alloy M1 and the hardened layer 60, and FIG. 5(b) shows a backscattered electron image of the cross-section of the second alloy 70. The Z direction in FIG. 5 indicates the stacking direction.

[0063] As shown in FIGS. 5(a) and 5(b), the hardened layer 60 was formed in the first alloy M1, and its thickness was 30 to 40 μm (0.03 m to 0.05 mm). On the other hand, it was confirmed that no hardened layer in which nitrides were formed was formed in the second alloy 70. In other words, it was confirmed that it is possible to selectively form a hardened layer on the surface of the first alloy M1. The reason why no hardened layer was formed in the second alloy 70 is considered to be that when the second alloy contains 1 atomic % or more and 35 atomic % or less of Ti and Cr, even if nitriding treatment is performed, nitrogen preferentially reacts with Ti and Cr, so that nitrogen does not diffuse into the second alloy.

[0064] (Hardness measurement) The hardness measurement was performed using a Vickers hardness tester (microhardness tester FM-110, manufactured by Future-Tech Corporation). Table 3 shows the hardness H1 of the first alloy M1 having the hardened layer 60, the hardness H2 of the second alloy 70, and the hardness ratio (H1 / H2), respectively. The measurement conditions were a load of 0.1 kgf and a holding time of 10 seconds. The measurement positions were set such that the surface of the second alloy 70 was 0 mm, at intervals of 0.03 mm up to 0.27 mm in the direction opposite to the lamination direction (Z direction) (a total of 9 locations), the surface of the hardened layer 60 was 0 mm, and at intervals of 0.03 mm up to 0.27 mm in the lamination direction (a total of 9 locations). Also, Fig. 6 shows the change in hardness in the direction from the surface of the hardened layer 60 towards the inside.

Table 3

[0065] As shown in Fig. 6, when comparing the hardness measured at intervals of 0.03 mm from the surface up to 0.27 mm inside for the hardened layer 60 and the second alloy 70, the hardened layer 60 was 742 HV at the location 0.03 mm from the surface, and in the range of 418 - 458 HV from 0.06 mm to 0.27 mm. On the other hand, the second alloy 70 showed results varying in the range of 476 - 530 HV. This is considered to be due to the fact that no hardened layer is formed on the surface of the second alloy 70. It was confirmed that the second alloy 70 is harder in the interior (for example, the part exceeding 100 μm from the surface).

[0066] In other words, between the hardened layer 60 and the second alloy 70, the magnitude relationship of hardness is different between the surface and the interior. For the first alloy M1 provided with the hardened layer 60, although the hardened layer 60 itself formed by nitriding treatment is hard, the hardness decreases inside the hardened layer 60. On the other hand, the second alloy does not have the hardness like the hardened layer 60, but there is no difference in hardness between the surface layer and the interior of the alloy. Therefore, for example, at locations where external forces such as compression or wear are applied, the second alloy having substantially the same hardness from the surface layer to the interior of the alloy is arranged, and at locations where impacts are applied, the first alloy with a hard surface layer of the alloy is arranged, etc., enabling optimal arrangement. Also, locations with different hardnesses and corrosion resistances can be arranged.

[0067] In addition, when damage such as wear, crack, or deformation occurs in the second alloy 70, it is assumed that after removing the damaged part by scraping it off or the like, additive manufacturing is performed again. At this time, since the hardened layer 60 is not formed in the second alloy 70, machining such as cutting becomes easy. Further, since the hardened layer 60 is not formed on the surface of the second alloy 70, it is possible to prevent gas defects and cracks derived from the hardened layer 60.

[0068] In addition, the second alloy 70 maintains a hardness of 470 HV or more even when held at the treatment temperature of the nitriding treatment, and no decrease in hardness due to the nitriding treatment was confirmed. From this result, like the second alloy 70, containing 5 elements of Co, Cr, Fe, Ni, and Ti as main components in the range of 5 atomic % or more and 35 atomic % or less respectively, and containing Mo as a sub-component in the range of more than 0 atomic % and 8 atomic % or less, with the balance consisting of unavoidable impurities, by setting it as the second alloy 70, since the hardened layer 60 can be selectively formed on the surface other than the second alloy 70, for example, the surface of the first alloy M1, it is expected to realize an alloy member selectively provided with corrosion resistance, wear resistance, etc. according to the application of the alloy member.

[0069] As described above, the above-described embodiments and examples have been described to assist in understanding the present invention, and the present invention is not limited to the specific configurations described. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can also be added to the configuration of one embodiment. That is, in the present invention, a part of the configuration of the embodiments and examples in this specification can be deleted, replaced with other configurations, or other configurations can be added. By adjusting such embodiments, the alloy member disclosed in the present invention can be applied to corrosion-resistant and wear-resistant parts widely used in industrial fields, resource fields, chemical plants, die members, etc.

Explanation of Reference Numerals

[0070] 1: Additive manufacturing apparatus 3: Powder supply nozzle 5: Focusing lens 7: Protection lens 9: Laser beam 11: Alloy powder 13: Melt pool 15: Formed body (alloy member) 17: Substrate 40: Alloy member 50: Substrate (first alloy M1) 60: Hardened layer 70: Second alloy

Claims

1. A first alloy; and a second alloy having a different composition from the first alloy, The first alloy and the second alloy are disposed in a continuous and integral manner; The first alloy has a hardened layer composed of nitrides on a surface thereof, The second alloy contains each of the elements Co, Cr, Fe, Ni, and Ti in the range of 1 atomic % or more and 35 atomic % or less, contains Mo in the range of more than 0 atomic % and 8 atomic % or less, contains B in the range of 0.15% or less, and contains either or both of Nb and Ta in the range of 10.0% or less, An alloy part, characterized in that the hardness of the hardened layer is 1.2 times or more greater than the hardness of the second alloy surface.

2. a molding step of spraying a second alloy powder having a composition different from that of the first alloy onto a first alloy, and irradiating the second alloy powder with a heat source to melt and solidify the second alloy powder onto the first alloy, thereby obtaining an alloy part; A surface treatment step of forming a hardened layer on the first alloy surface of the alloy member, The second alloy contains each of the elements Co, Cr, Fe, Ni, and Ti in the range of 1 atomic % or more and 35 atomic % or less, Mo in the range of more than 0 atomic % and 8 atomic % or less, B in the range of 0.15% or less, and either or both of Ta and Nb in the range of 10.0% or less.

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