Manufacturing method for alloy components

Abstract

To provide a method for manufacturing alloy components that can improve the crack resistance of Ni-based alloys. [Solution] A method for manufacturing an alloy member, comprising: preparing a Ni-based alloy forming powder consisting of Cr: 14% to 24%, Mo: 14% to 24%, Ta: 1.0% to 2.5%, with the remainder being Ni and unavoidable impurities by mass%, and a metal carbide powder consisting of at least one metal element selected from Ta, Nb, Ti, V, and Zr and C; mixing the Ni-based alloy forming powder and the metal carbide powder such that the mass ratio of the metal carbide powder to the total mass of the Ni-based alloy forming powder and the metal carbide powder is greater than 0% and less than 10% to obtain a carbide-containing mixed powder; and irradiating the carbide-containing mixed powder with energy rays to melt and solidify it to form an alloy layer.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing alloy members. [Background technology]

[0002] An injection molding machine is equipped with a cylinder that heats and melts the injected resin, and a screw that injects the molten resin into a mold while mixing it. When the resin melts, corrosive gases such as sulfur gases may be generated, so the screws and cylinders used for injection molding need to have corrosion resistance to withstand these corrosive gases. In addition, when molding fiber-reinforced plastics, glass fibers, carbon fibers, etc. are added to the resin, so wear resistance, i.e., hardness, is also required. Such screws and cylinders are sometimes manufactured using additive manufacturing methods to create complex shapes.

[0003] Conventionally, nickel-based alloys (Ni-Cr-Mo alloys), which have the highest mass ratio of nickel (Ni), followed by chromium (Cr) and molybdenum (Mo), have been known as alloys with excellent corrosion resistance and high hardness. Patent Document 1 describes a nickel-based alloy powder and an adduct manufactured using this powder, which contains, by mass percent, Cr: 18-22%, Mo: 18-28%, carbon (C): 1.0-2.5%, niobium (Nb): 0-19.34%, titanium (Ti): 0-12%, vanadium (V): 0-12%, with the remainder being 37.5% or more of Ni and unavoidable impurities, and which has excellent corrosion resistance, wear resistance, and crack resistance. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] WO2021 / 201118 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, in order to manufacture an additional product as described in Patent Document 1, Ni-based alloy powder containing C is created by an atomization method. When Mo is contained in the Ni-based alloy powder, there is a problem that Mo and C may combine to form Mo carbide, resulting in a decrease in crack resistance.

[0006] The present invention has been made to solve such problems, and provides a method for manufacturing an alloy member capable of improving the crack resistance of a Ni-based alloy.

Means for Solving the Problems

[0007] A method for manufacturing an alloy member according to a first aspect of the present invention is a powder for forming a Ni-based alloy composed of, in mass%, Cr: 14% or more and 24% or less, Mo: 14% or more and 24% or less, Ta: 1.0% or more and 2.5% or less, with the balance being Ni and unavoidable impurities, and a metal carbide powder composed of at least one metal element selected from Ta, Nb, Ti, V, Zr and C are prepared. The Ni-based alloy-forming powder and the metal carbide powder are mixed so that the mass ratio of the metal carbide powder to the total mass of the Ni-based alloy-forming powder and the metal carbide powder is more than 0% and less than 10% to obtain a carbide-containing mixed powder. Irradiating the carbide-containing mixed powder with energy rays and melting and solidifying it to form an alloy layer is one of the features.

[0008] At this time, the alloy layer is formed by solidifying on a metal base material, and it is preferable that the solidification structure of the alloy layer has a dendritic crystal structure and metal carbide.

[0009] Further, the metal carbide powder preferably contains, in mass%, 15% or more and 25% or less of C and 75% or more and 85% or less of Ti.

Effects of the Invention

[0010] According to the present invention, a method for manufacturing an alloy member capable of improving the crack resistance of a Ni-based alloy is provided.

Brief Description of the Drawings

[0011] [Figure 1] This is a diagram showing the schematic configuration of an additive manufacturing apparatus of the DED method used in the method for manufacturing an alloy member which is an embodiment of the present invention. [Figure 2] This is a cross-sectional view schematically showing an example of the alloy member of the present invention. [Figure 3A] This is an optical microscope image showing the solidification structure of Example 1 according to the present invention. [Figure 3B] This is an optical microscope image showing the solidification structure of Example 2 according to the present invention. [Figure 3C] This is an optical microscope image showing the solidification structure of Comparative Example 1. [Figure 3D] This is an optical microscope image showing the solidification structure of Comparative Example 2. [Figure 3E] This is an optical microscope image showing the solidification structure of Comparative Example 3. [Figure 4A] This is a backscattered electron image obtained by a scanning electron microscope and an elemental mapping diagram obtained by energy dispersive spectrometry, showing the solidification structure of Example 1 according to the present invention. [Figure 4B] This is a backscattered electron image obtained by a scanning electron microscope and an elemental mapping diagram obtained by energy dispersive spectrometry, showing the solidification structure of Example 2 according to the present invention. [Figure 4C] This is a backscattered electron image obtained by a scanning electron microscope and an elemental mapping diagram obtained by energy dispersive spectrometry, showing the solidification structure of Comparative Example 1. [Figure 4D] This is a backscattered electron image obtained by a scanning electron microscope and an elemental mapping diagram obtained by energy dispersive spectrometry, showing the solidification structure of Comparative Example 2. [Figure 4E] This is a backscattered electron image obtained by a scanning electron microscope and an elemental mapping diagram obtained by energy dispersive spectrometry, showing the solidification structure of Comparative Example 3.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments for implementing the present invention will be described as appropriate with reference to the drawings. First, after describing the manufacturing method of the alloy member according to the first embodiment, the alloy member according to the second embodiment obtained by such a manufacturing method will be described. Note that the present invention is not limited to the following embodiments.

[0013] The manufacturing method of the alloy member according to the first embodiment of the present invention is as follows: In terms of mass%, for the powder for forming a Ni-based alloy consisting of Cr: 14% or more and 24% or less, Mo: 14% or more and 24% or less, Ta: 1.0% or more and 2.5% or less, and the balance being Ni and unavoidable impurities, and a metal carbide powder composed of at least one metal element selected from Ta, Nb, Ti, V, Zr and C are prepared. The powder for forming a Ni-based alloy and the metal carbide powder are mixed so that the mass ratio of the metal carbide powder to the total mass of the powder for forming a Ni-based alloy and the metal carbide powder is more than 0% and less than 10%, thereby obtaining a carbide-containing mixed powder. The carbide-containing mixed powder is irradiated with energy rays to be melted and solidified on a metal base material to form an alloy member having a layered or three-dimensional shape.

[0014] Note that the powder for forming a Ni-based alloy may be a mixed powder obtained by mixing powders of Ni, Cr, Mo, and Ta in powder form, or an alloy powder containing all types of elements of Ni, Cr, Mo, and Ta. Also, the carbide-containing mixed powder may be mixed so that the mass ratio of the metal carbide powder to the total mass of the powder for forming a Ni-based alloy and the metal carbide powder is more than 0% and less than 10%.

[0015] Details of the chemical composition and content of the alloy member will be described. Hereinafter, when simply described as %, it refers to mass%. Also, the numerical range represented by "~" 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.

[0016] <Powder for forming a Ni-based alloy (Ni-Cr-Mo alloy system)> The alloy member produced in the first embodiment of the present invention is formed by adding metal carbide powder to Ni-based alloy forming powder. The alloy member thus produced contains a face-centered cubic (FCC) phase. The FCC phase contains Cr, Mo, and Ni as the main constituent elements and Ta as the secondary constituent element, with Ni having the highest mass ratio, followed by Cr and Mo. Ni, Cr, Mo, and Ta are essential elements that are always included in the Ni-based alloy forming powder used in this embodiment. In this specification, "Ni-based" refers to an alloy with the highest Ni content.

[0017] In the total Ni-based alloy forming powder, the main constituent elements, Cr and Mo, are present in mass percent as follows: Cr: 14-24% and Mo: 14-24%. The minor constituent element, Ta, is present in mass percent as follows: 1.0-2.5%.

[0018] The powder used to form Ni-based alloys is composed of Ni and unavoidable impurities, with the substantial remainder being the mass fraction of the essential elements Cr, Mo, and Ta combined. Optional elements that can be added include Nb, Ti, V, Zr, Y (yttrium), Hf (hafnium), W, and B (boron).

[0019] Here, we will explain in detail the chemical composition and content of the Ni-based alloy forming powder mentioned above.

[0020] (Cr: 14% or more and 24% or less) Cr is added because it has the effect of improving corrosion resistance. In particular, Cr forms a passive film on the powder surface or the alloy surface, so Ni-based alloys containing Cr provide corrosion resistance to nitric acid, sulfuric acid, hydrofluoric acid, etc. A Cr content of 14% or more provides sufficient improvement in corrosion resistance. On the other hand, if the Cr content exceeds 24%, when combined with Mo, etc., it forms intermetallic compounds such as coarse μ phase (Ni7Mo6, etc.) or P phase (Mo3(Mo,Cr)5Ni6, etc.), resulting in reduced corrosion resistance and crack resistance. Furthermore, if elements that easily form carbides, such as Ta, are added, the concentration of Cr in carbides and grain boundaries is suppressed, so excessive addition of Cr is not required. Therefore, the amount of Cr should be between 14% and 24%. Preferably, it is between 18% and 20%.

[0021] (Mo: 14% or more and 24% or less) Mo is added because it has the effect of improving corrosion resistance. In particular, Mo densely strengthens the passive film formed by Cr, so Ni-based alloys containing Mo exhibit excellent corrosion resistance to hydrochloric acid, sulfuric acid, hydrofluoric acid, etc. When the Mo content is 14% or more, the effect of improving corrosion resistance by Mo is sufficiently obtained in combination with Cr. On the other hand, when the Mo content exceeds 24%, M6C type carbides or M are formed in proportion to the amount of Mo. 12 The increase in C-type carbides (where M represents a metallic element) significantly reduces crack resistance. When alloy powders are used in additive manufacturing, the additively fabricated body (also simply called the fabricated body) becomes prone to cracking, making proper fabrication difficult.

[0022] Furthermore, since Mo is easily oxidized at high temperatures, when alloy powder is manufactured by gas atomization or other methods, an oxide film is easily formed on the surface of the alloy powder. If powder with an oxide film formed on it is used in additive manufacturing, this powder may cause a smoke phenomenon where it is stirred up during additive manufacturing, or it may be mixed into the additively manufactured body as an impurity. For this reason, the amount of Mo should be between 14% and 24%. Preferably, it should be between 18% and 20%.

[0023] (Ta: 1.0% or more and 2.5% or less) Ta (T) is added because it improves corrosion resistance. Ta strengthens and improves the passive film formed by Cr (Cr), so Ni-based alloys containing Ta exhibit excellent corrosion resistance. In particular, when combined with Cr or Mo (Mo), Ta significantly strengthens the passive film, resulting in greatly improved corrosion resistance to acids in Ni-based alloys containing Ta. Furthermore, a Ta content of 1.0% or more provides sufficient corrosion resistance improvement.

[0024] On the other hand, if there is an excess of Ta, the intermetallic compounds increase, leading to reduced crack resistance, and Mo becomes concentrated in the intermetallic compounds, resulting in reduced corrosion resistance. Although it also depends on whether or not Ta is contained in the metal carbide powder described later, for Ni-based alloy forming powders that do not contain more C than unavoidable impurities, it is preferable that the Ta content does not exceed 2.5% at most. Therefore, the amount of Ta is set to 1.0% or more and 2.5% or less, preferably 1.5% or more and 2.2% or less.

[0025] (Nb, Ti, V, Zr) Nb, Ti, V, and Zr are carbide-forming elements with lower carbide-forming free energies than Mo. By combining with carbon (C) contained in the metal carbide powder described later, they form carbides in the matrix phase, contributing to improved wear resistance. Furthermore, the combination of Mo and C results in the formation of the aforementioned M6C type carbides or M 12 It is preferable to add it to Ni-based alloy forming powder because it prevents the formation of C-type carbides and contributes to improved crack resistance.

[0026] When the mass percentages of Nb exceed 42%, Ti exceed 15%, V exceed 27%, and Zr exceed 29%, the carbide content becomes excessive, reducing crack resistance and corrosion resistance. Therefore, the respective content should be 0% to 42% for Nb, 0% to 15% for Ti, 0% to 27% for V, and 0% to 29% for Zr, all expressed in mass percentages. Even if the Ni-based alloy forming powder does not contain these elements, a similar effect can be achieved if they are included in the metal carbide powder described later, so this method may also be used.

[0027] (Y) Like chromium (Cr), yellow (Y) forms a stable passive film, improving oxidation and corrosion resistance. Furthermore, due to its relatively large atomic radius, it also improves alloy strength and wear resistance. The benefits of Y are obtained when the Y content is 0.01% or more by mass. However, exceeding 5.0% can lead to increased oxidation and a decrease in oxidation resistance. Therefore, when actively adding Y, its content should be between 0.01% and 5.0%.

[0028] (Hf) Hf has a carbide-forming ability similar to that of Ta, Ti, and Zr. Since Hf has a lower carbide-forming energy than Cr, the formation of Hf carbides can suppress Cr depletion, thereby improving corrosion resistance. Furthermore, because metal carbides such as Hf carbides are highly hard, their dispersion in the alloy improves wear resistance. On the other hand, if the Hf content is excessive, harmful intermetallic compounds may form, potentially reducing crack resistance. Therefore, when Hf is actively added, its content should be between 0.01% and 56% by mass. It is preferable to add Hf as a substitute element for one or more of the elements among Ta, Ti, and Zr, and to limit the total amount of Hf and other carbide-forming elements added in atomic percent to a range of similar amounts.

[0029] (W) W has a higher carbide-forming ability than Mo. Furthermore, due to its large atomic radius, it can be expected to improve alloy strength and wear resistance through solid solution strengthening. The effects of W addition can be obtained when the W content is 0.01% or higher. On the other hand, excessive W content can form harmful intermetallic compounds, potentially reducing crack resistance. Therefore, when actively adding W, its content should be between 0.01% and 30%.

[0030] (B) B is expected to improve alloy strength, particularly high-temperature strength, through grain boundary strengthening. It is also expected to improve wear resistance through boride precipitation. The effects of adding B can be obtained when the B content is 0.001% or more by mass. On the other hand, if the B content is excessive, crack resistance decreases. Therefore, when B is actively added, its content should be between 0.001% and 1%, preferably between 0.001% and 0.1%.

[0031] (Inevitable impurities) Unavoidable impurities refer to trace amounts of impurities that are technically difficult to remove, resulting from trace elements mixed into the raw materials or reactions with various components that come into contact during the manufacturing process. In the case of the Ni-based alloy forming powder used in this embodiment, unavoidable impurities specifically refer to, for example, C, Si, Mn, P, S, Co, Fe, V, Al, N, and O. Of these impurities, those that should be particularly restricted are P, S, N, and O. Preferably, P is 0.02% or less by mass, S is 0.02% or less, N is 0.06% or less, and O is 0.025% or less. Of course, it is preferable that the content of these unavoidable impurities be as low as possible, and 0% is even better.

[0032] [Form of Ni-based alloy forming powder] The Ni-based alloy forming powder used in this embodiment may be a mixed powder made by mixing multiple types of pure metal powders of Ni, Cr, Mo, and Ta, or alloy powders made by melting multiple types of metal powders, as long as the total Ni-based alloy forming powder consists of, by mass%, Cr: 14% to 24%, Mo: 14% to 24%, Ta: 1.0% to 2.5%, with the remainder being Ni and unavoidable impurities. Hereafter, when referring to Ni-based alloy forming powder, it will refer to the mixed powder or the Ni-based alloy powder. Furthermore, from the viewpoint of the fluidity of the raw material powder, it is preferable to shape it into a spherical shape by gas atomization or by spheroidizing treatment by thermal plasma droplet refining (PDR).

[0033] Ni-based alloy powder contains Cr, Mo, and Ta in the predetermined compositions described above, with the remainder being Ni and unavoidable impurity elements. First, predetermined amounts of each elemental supply material (Ni, Cr, Mo, Ta) are measured to obtain an alloy within a predetermined composition range, and these are mixed to produce a mixed powder. Ni-based alloy powder is obtained by performing an atomization method using this mixed powder. For example, the mixed powder is loaded into a crucible, melted by high-frequency induction, the molten alloy is dropped from a nozzle below the crucible, and the mixture is atomized with high-pressure argon to produce spherical powder by gas atomization. Ni-based alloy powder can be obtained by classifying this spherical powder.

[0034] <Metal carbide powder> The metal carbide powder used in this embodiment consists of a carbide powder comprising at least one metal element selected from Ta, Nb, Ti, V, and Zr, and C, as well as unavoidable impurities. Nb, Ti, V, and Zr are carbide-forming elements with lower carbide-forming free energies than Mo. By combining with carbon (C) contained in the metal carbide powder described later, they form carbides in the matrix phase, contributing to improved wear resistance. Furthermore, the combination of Mo and C results in the formation of the aforementioned M6C type carbides or M 12 It is preferable to add it to Ni-based alloy forming powder because it prevents the formation of C-type carbides and contributes to improved crack resistance.

[0035] When the mass percentages of Nb exceed 42%, Ti exceed 15%, V exceed 27%, and Zr exceed 29%, the amount of carbides becomes excessive, reducing crack resistance and corrosion resistance. Therefore, the respective content should be 0% to 42% for Nb, 0% to 15% for Ti, 0% to 27% for V, and 0% to 29% for Zr.

[0036] By mixing such carbide powder with Ni-based alloy forming powder and subjecting it to addition manufacturing, carbide particles are dispersed in the resulting alloy layer, improving hardness and wear resistance. Furthermore, since Ta, Nb, Ti, V, and Zr have lower carbide formation free energies than Mo, the aforementioned M6C type carbide or M is formed by the bonding of Mo and carbon. 12 It suppresses the formation of C-type carbides, contributing to improved crack resistance.

[0037] In the case of the metal carbide powder used in this embodiment, the inevitable impurities are specifically Fe, O, etc. In terms of mass%, Fe is preferably 0.1% or less, and O is preferably 0.2% or less. Of course, it is preferable that the content of these inevitable impurities is less, and it is even better if it is 0%. Further, the metal carbide powder used in this embodiment is preferably spheroidized by the PDR method from the viewpoint of the fluidity of the raw material powder, but it is not limited to the spherical shape.

[0038] <Powder mixture of Ni-based alloy-forming powder and metal carbide powder> The Ni-based alloy-forming powder and the metal carbide powder are mixed to obtain a carbide-containing mixed powder. Also, in the method for manufacturing an alloy member according to the first embodiment of the present invention, the Ni-based alloy-forming powder and the metal carbide powder are prepared separately and mixed before additive manufacturing. By doing so, the mixing amount of the metal carbide powder can be adjusted according to the required hardness of the alloy member. By adjusting the amount of the metal carbide powder during additive manufacturing, the hardness can also be changed for each part of the alloy member.

[0039] Also, a metal carbide powder in which an element having a lower carbide formation free energy than Mo is combined with C in advance is prepared and mixed with the Ni-based alloy-forming powder before additive manufacturing, thereby reducing the possibility of forming Mo carbide. When trying to produce an alloy powder containing metal carbide by the atomization method, the nozzle of the atomizer becomes clogged due to carbide having a melting point higher than the atomization temperature, and the yield decreases.

[0040] On the other hand, when a carbide-containing mixed powder, obtained by mixing Ni-based alloy forming powder (powder without metal carbides) and metal carbide powder, is used in an additive manufacturing process, the atomization process is not performed in the first place, eliminating concerns about clogging of the atomizer nozzle and improving yield. In this case, the carbide-containing mixed powder may consist of a mixed powder containing all of Ni, Cr, Mo, and Ta and a metal carbide powder containing one or more of Nb, Ti, Ta, V, or Zr, or it may be a mixture of Ni-based alloy powder containing all of Ni, Cr, Mo, and Ta obtained in advance by an atomization process and a metal carbide powder containing one or more of Nb, Ti, Ta, V, or Zr.

[0041] The mass ratio of metal carbide powder to the total carbide-containing mixed powder is between 0% and less than 10%. The inclusion of metal carbide powder is necessary because it disperses carbide particles within the resulting alloy layer, improving wear resistance. However, too much metal carbide powder can lead to the formation of coarse carbide phase aggregates, causing cracking; therefore, the ratio should be kept below 10%.

[0042] Preferably, the content is greater than 0% and less than or equal to 5%, and more preferably between 2.5% and 5%. Furthermore, when both the Ni-based alloy forming powder and the metal carbide powder contain Ta, it is preferable that the Ta content be 2.5% by mass or less when these are mixed to produce a carbide-containing mixed powder. This is because, as mentioned above, if the Ta content exceeds 2.5%, there is a risk that the crack resistance and corrosion resistance will decrease.

[0043] <Method for manufacturing alloy components> In the manufacturing of the alloy member of this embodiment, a carbide-containing mixed powder is used, which is obtained by mixing Ni-based alloy forming powder with the aforementioned metal carbide powder. The carbide-containing mixed powder is irradiated with an energy beam such as an electron beam or a laser beam to melt and solidify it, and a solidified layer is formed by sequentially changing the irradiation position. A new solidified layer is formed on top of the solidified layer, and this operation is repeated thereafter to obtain an alloy member with a laminated structure. In other words, it is manufactured by a so-called additive manufacturing method.

[0044] <Additive manufacturing method> The various raw materials and powders used in this embodiment can be used in addition manufacturing methods of any appropriate type. Generally, addition manufacturing methods for metal materials are broadly classified into powder bed fusion (PBF) and directed energy deposition (DED).

[0045] The PBF (Powder-Blowing) method involves forming a powder bed by spreading metal powder on a substrate or an already formed powder bed, and then irradiating the metal powder in the target area with energy rays to melt and solidify the metal powder, thereby creating the object. In the PBF method, each time a two-dimensional object is created on the powder bed, a three-dimensional additive manufacturing process is performed, repeating the layering of the powder bed and the melting and solidification of the metal powder. Finally, the composite alloy component formed on the substrate is removed together with the substrate, and the alloy component is obtained by separating the substrate and the alloy component through machining or other methods.

[0046] There are two types of PBF (Powder-Blowing) methods: one that uses a laser beam as the energy source, and another that uses an electron beam. The method using a laser beam is broadly classified into Selective Laser Melting (SLM) and Selective Laser Sintering (SLS). The method using an electron beam is called Selective Electron Beam Melting (SEBM, or simply EBM).

[0047] On the other hand, the DED method involves supplying metal powder and irradiating it with energy rays onto a substrate or an already formed build area, melting and solidifying the metal powder supplied to the build area to form the object. In the DED method, the supply of metal powder and irradiation with energy rays are performed while changing the position in two or three dimensions, and three-dimensional additive manufacturing is carried out by repeatedly depositing solidified metal onto the already formed build area. Finally, the alloy member formed on the substrate is removed together with the substrate, and the substrate and alloy member are separated by machining to obtain the alloy member.

[0048] The DED method is also known as the metal deposition method. The DED method includes the Laser Metal Deposition (LMD) method, which uses a laser beam as the energy source, and the method that uses an electron beam as the energy source. Among the DED methods, the method of applying powder buildup to a substrate using a laser beam is also called laser powder buildup welding.

[0049] Among various additive manufacturing methods, the PBF method has the advantage of high shape accuracy for additively manufactured bodies. On the other hand, the DED method has the advantage of enabling high-speed manufacturing. In this invention, both the PBF method and the DED method can be selected. Below, an example in which the DED method is adopted as one embodiment will be described.

[0050] Figure 1 shows a schematic configuration of a DED (Directed Emission Development) additive manufacturing apparatus 1. The additive manufacturing apparatus 1 mainly consists of a powder supply nozzle 3, a focusing lens 5, a protective lens 7, etc. A carbide-containing mixed powder 11 is supplied to the powder supply nozzle 3 and injected together with argon gas to the tip of the powder supply nozzle 3. 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.

[0051] In additive manufacturing, a powder supply nozzle 3 is moved relative to the substrate 17 while supplying a carbide-containing mixed powder 11 onto the substrate 17 (direction A in the figure). A laser beam 9 focused by a focusing lens 5 is irradiated onto the supplied carbide-containing mixed powder 11, forming a molten pool of carbide-containing mixed powder 11 on the substrate 17. By changing the irradiation position of the laser beam 9 or stopping the irradiation of the laser beam 9, solidification occurs, and an alloy layer 15 can be formed on the substrate 17. If necessary, this process is repeated to deposit a new alloy layer 15 on top of the alloy layer 15, thereby creating a three-dimensional alloy member on the substrate 17 that contains at least a portion of a Ni-based alloy. The additive manufacturing conditions are appropriately determined considering the particle size and composition of the raw material powder, the size, shape, and characteristics of the manufactured body, production efficiency, etc., but for the carbide-containing mixed powder 11 used in this embodiment, the following range can be selected.

[0052] When fabricating a single-walled object by stacking single beads only in the height direction, the thickness of each single bead can be, for example, 0.1 to 1.0 mm, preferably 0.2 to 0.4 mm. The laser beam diameter is preferably about 3 mm at the irradiation position. The laser output is preferably 1500 to 2500 W. The laser scanning speed is preferably 1500 to 5000 mm / min. The total amount of carbide-containing mixed powder 11 supplied is preferably 10 to 20 g / min.

[0053] To rapidly melt the carbide-containing mixed powder 11, the energy density (energy density of the heat source: J / mm) supplied by laser beam irradiation is preferably 20 to 200 J / mm, and more preferably in the range of 30 to 100 J / mm. If the energy density is too low, the defect rate will increase, and furthermore, the supplied powder will not melt, making it difficult to maintain the shape of the molded object. On the other hand, if the energy density is too high, a wide area of ​​the substrate or molded object centered on the laser beam irradiation position will melt, making it difficult to maintain the shape of the molded object. The energy density E (J / mm) can be calculated using the laser output P (W) and laser scanning speed v (mm / min) from equation (1): E = (P / v) × 60...

[0054] <Particle size distribution of carbide-containing mixed powder 11> For the carbide-containing mixed powder 11 used in this embodiment, the average particle diameter d corresponding to 50% by volume of the integrated frequency of the powder in the cumulative particle size distribution measured by laser diffraction scattering type is 50 preferably in the range of 5 to 500 μm. In the additive manufacturing method, melting and solidification proceed for each collection of a certain amount of powder. If the particle diameter of the powder is too small, the bead will also be small, so defects such as interface fracture of the bead are likely to occur. On the other hand, if the particle diameter of the powder is too large, the bead will also be large, so defects due to non-uniform cooling rate are likely to occur. However, if the average particle diameter d 50 is within the range of 5 to 500 μm, it is easier to obtain a laminated structure body with few defects.

[0055] However, the optimal particle diameter and particle size distribution of the carbide-containing mixed powder 11 vary depending on the type of additive manufacturing method. Therefore, it is preferable to adjust the particle diameter and particle size distribution of the carbide-containing mixed powder 11 according to the type of additive manufacturing method. From the perspective of using the carbide-containing mixed powder 11 in the PBF method or DED method, the average particle diameter d 50 is preferably within the range of 10 to 250 μm, and more preferably within the range of 20 to 150 μm.

[0056] For example, in the SLM method, the average particle diameter d corresponding to 50% by volume of the integrated frequency of the carbide-containing mixed powder 11 in the cumulative particle size distribution measured by laser diffraction scattering type is 50 preferably 10 to 60 μm, more preferably 20 to 40 μm. Also, the particle diameter d corresponding to 10% by volume of the integrated frequency is 10 preferably 5 to 35 μm. Also, the particle diameter d corresponding to 90% by volume of the integrated frequency is 90 preferably 20 to 100 μm.

[0057] In the SLM method, if the individual particle size of the carbide-containing mixed powder 11 is less than 10 μm, the deposition and spreadability of the powder as a granular material will be poor, making it easy for the powder to be unevenly layered as a powder bed. Also, if the individual particle size exceeds 100 μm, melting by the laser beam 9 is likely to be incomplete, resulting in defects in the solidified structure or increased surface roughness. However, with the aforementioned particle size, it is easy to form a powder bed with a flat and uniform thickness, and it is also easy to repeatedly layer the powder bed, making it easier to obtain an additively fabricated body with fewer defects.

[0058] Furthermore, in the LMD method and EBM method, the average particle size d corresponding to the cumulative particle size distribution of carbide-containing mixed powder 11 at a cumulative frequency of 50% by volume is measured by laser diffraction scattering particle size distribution measurement. 50 The particle size is preferably 30 to 250 μm, more preferably 60 to 120 μm. Also, the particle size d corresponding to the cumulative frequency of 10 volume% of the carbide-containing mixed powder 11. 10 The particle size is preferably 15 to 100 μm. Also, the particle size d corresponding to the cumulative frequency of the powder at 90% by volume is also specified. 90 The particle size is preferably 50 to 500 μm.

[0059] In the LMD method, if the average particle size of the carbide-containing mixed powder 11 is small, the flow of powder conveyed to the nozzle head tends to be uneven, making it difficult to supply a stable amount of metal powder to the molten pool. Also, if the individual particle size exceeds about 500 μm, the metal powder may clog the nozzle head, resulting in incomplete melting, defects in the solidified structure, and increased surface roughness. On the other hand, in the EBM method, if the average particle size of the metal powder is small, the smoke phenomenon is more likely to occur. However, with the aforementioned particle size, the supply of metal powder to the molten pool and the non-scattering of metal powder are improved, making it easier to obtain high-precision additively fabricated bodies.

[0060] Particle size distribution and particle diameter can be measured, for example, using a laser diffraction scattering type particle size distribution analyzer. The average particle diameter is determined as the particle diameter corresponding to 50% of the volume accumulated from the smallest particle diameter to the largest particle diameter in the integrated volume distribution curve, which shows the relationship between the integrated volume value obtained by accumulating the volume of particles from the smallest particle diameter to the largest particle diameter, and the particle diameter in that integrated volume value.

[0061] <Method for mixing the carbide-containing mixed powder 11> Such carbide-containing mixed powder 11 may be prepared by mixing the Ni-based alloy forming powder and the metal carbide powder before supplying it to the additive manufacturing apparatus, or a mixing space may be provided within the additive manufacturing apparatus to mix the Ni-based alloy forming powder and the metal carbide powder before transporting it to the powder supply nozzle 3. By providing a mixing space within the additive manufacturing apparatus, it is only necessary to set the respective Ni-based alloy forming powder and metal carbide powder in the powder supply device, thus shortening the manufacturing process and the process of transporting the carbide-containing mixed powder 11 from a mixed powder manufacturing device outside the additive manufacturing apparatus.

[0062] <Composite alloy components> The alloy member (member) manufactured by addition using the carbide-containing mixed powder 11 of this embodiment is an alloy layer or a three-dimensional molded object formed using the carbide-containing mixed powder 11 having the above chemical composition, and can be integrated with other members to obtain a composite alloy member.

[0063] Figure 2 is a schematic cross-sectional view showing an example of a composite alloy member 21 manufactured by an addition process using the carbide-containing mixed powder 11 of this embodiment. Figure 2 shows an example of a composite alloy member 21 in which the alloy layer 15 is overlaid on a base material 17 made of a different material from the alloy layer formed using the carbide-containing mixed powder 11 having the above chemical composition.

[0064] As shown in Figure 2, the composite alloy member 21 of this embodiment comprises a metal base material 17 and an alloy layer 15 formed on the surface of the base material 17 using powder having the aforementioned chemical composition. Such a composite alloy member 21 can be manufactured, for example, by a DED (Directed Edible Deposition) additive manufacturing method using alloy powder.

[0065] The base material 17 is not particularly limited in shape or material, as long as it is made of metal. For example, Fe-based alloys, Ni-based alloys, etc., can be used as the base material 17. However, since the material of the base material 17 affects the susceptibility to cracking at the boundary with the alloy layer 15, it is preferable to use a Ni-based alloy or an Fe-based alloy with a carbon content of 0.9 mass% or less as the material of the base material 17 in order to reduce the likelihood of cracking. Specifically, it is more preferable that the carbon content of the base material 17 be HPM38, HPM31, or HPM75 or less for plastic mold steel. Furthermore, the shape and thickness of the alloy layer 15 are not particularly limited. In Figure 2, the alloy layer 15 is formed as a block-shaped layer on the surface of the base material 17 by powder buildup. However, the alloy layer 15 may be formed as a thin film coating that covers the surface of the base material for heat resistance, wear resistance, etc., or as an additively fabricated body exhibiting a predetermined three-dimensional shape.

[0066] Conventionally, alloy components made of an alloy and a dissimilar material are often manufactured by sintering or HIP (High-Intensity Pressing) methods. However, because alloys and dissimilar materials usually have different coefficients of thermal expansion, the alloy tends to peel off from the dissimilar material during the cooling process after sintering. In contrast, the composite alloy component 21 of this embodiment can be manufactured by an additive manufacturing method using a powder having the above-mentioned chemical composition as the material.

[0067] During the melting and solidification process of the carbide-containing mixed powder 11, a mixed layer 19 is formed between the base material 17 and the alloy layer 15. The mixed layer 19 has an intermediate chemical composition between the base material 17 and the alloy layer 15 because the components contained in the base material 17 and the alloy layer 15 are diluted during melting and solidification. The mixed layer 19 reduces the difference in the coefficient of linear expansion between the base material 17 and the alloy layer 15, thereby improving the adhesion of the alloy layer 15 and preventing delamination.

[0068] The shape of the composite alloy member 21 manufactured using the powder of this embodiment can be observed using an optical microscope. For example, as a test piece for observation, a part of the composite alloy member 21 is embedded in resin, and the cross-section of the embedded composite alloy member 21 is polished to a mirror finish. The observation magnification is set to 5x with an objective lens, and the observed images can be stitched together so that the entire cross-section becomes a single image.

[0069] Specific examples of applications for composite alloy members 21 include components used in equipment and structures where corrosion resistance and wear resistance are required, such as injection molding screws and cylinders, as well as drilling equipment for oil well plants, valves, fittings, heat exchangers, pumps, etc. installed in chemical plants, turbines for generators, impellers for compressors, and blades and discs for aircraft engines. Another example is molds that have been repaired with powder coating.

[0070] <Solidification structure of alloy layers> The solidification structure of the alloy layer 15 produced using the powder of this embodiment is mainly a face-centered cubic (FCC) structure, and has a metallic phase (matrix) mainly composed of metallic elements contained in the Ni-based alloy forming powder that constitutes the carbide-containing mixed powder 11, and a carbide phase in which the metallic elements contained in the Ni-based alloy forming powder and the metal carbide powder that constitute the carbide-containing mixed powder 11 are bonded with the carbon contained in the metal carbide powder. Since the solidification structure has a form in which a sufficient amount of the carbide phase is dispersed in the matrix phase, excellent wear resistance can be obtained.

[0071] In this embodiment, the composite alloy member 21 has a FCC structure in which the amount of Mo and Cr in the metal phase (matrix) is 14% or more by mass, preferably 18% or more. Since the elements Ti and Ta contained in the carbide-containing mixed powder 11 of this embodiment have a greater tendency to form carbides than Mo, the amount of Mo contained in the metal phase that is consumed for Mo carbide formation in the alloy member 21 of this embodiment is small. Therefore, even though the alloy layer 15 in the composite alloy member 21 of this embodiment is a carbide-dispersed type of reinforcing material, excellent corrosion resistance can be obtained.

[0072] In this embodiment, when the alloy layer 15 is formed by melting the carbide-containing mixed powder 11 and cooling it from above the liquidus temperature to below the solidus temperature, the solidification structure becomes dendritic. Therefore, by observing the presence or absence of a dendritic solidification structure, it is possible to confirm whether or not the manufactured alloy has undergone melting and solidification.

[0073] The solidification structure can be observed and analyzed using energy-dispersive X-ray spectroscopy (EDS) associated with a scanning electron microscope (SEM). For example, a specimen can be used in which a portion of the composite alloy member 21 is embedded in resin, and the cross-section of the embedded alloy is polished to a mirror finish.

[0074] For the analysis conditions, for example, the accelerating voltage in the scanning electron microscope should be 15kV, the working distance from the objective lens to the observation surface should be 10mm, and the observation magnification should be 2000x to 3000x. For evaluation of elemental analysis using EDS, a mapping image should be obtained by surface analysis in the same field of view as the above-mentioned SEM. The target elements can be, for example, six types: C, Cr, Mo, Ni, Ta, and Ti.

[0075] <Hardness> The hardness near the surface of the alloy layer 15 in the composite alloy member 21 of this embodiment can be evaluated using Vickers hardness HV (hereinafter referred to as hardness), and it is desirable that it be 350 HV or higher, and preferably 400 HV or higher.

[0076] For example, to measure Vickers hardness HV, the Vickers indenter load can be set to 0.2 kg, the residence time during indentation to 10 seconds, and the hardness can be determined from the length of the diagonal of the indentation formed on the surface by the indenter's indentation.

[0077] <Corrosion resistance> The corrosion resistance of the composite alloy member 21 in this embodiment can be evaluated, for example, by determining the corrosion rate of the composite alloy member in a strong acid. The corrosion rate when immersed in boiling 10% sulfuric acid for 24 hours is 0.3 g·m -2 ·h -1 The following is preferable:

[0078] For corrosion testing to evaluate corrosion resistance, a test specimen measuring 25 × 25 × 3 mm can be taken from the composite alloy member 21 of this embodiment, and its surface can be wet-polished and finished with #1000 emery paper.

[0079] Regarding the corrosion test method, for example, first, the weight of the test specimen (weight before the test) is measured. Then, a sulfuric acid aqueous solution prepared by diluting a special grade sulfuric acid reagent according to JIS K 8951 to 10 mass% with pure water is heated until the temperature reaches 100°C, and the test specimen is submerged in it. After 24 hours, the test specimen is removed from the sulfuric acid aqueous solution, the weight of the test specimen (weight after the test) is measured, and the weight change of the test specimen before and after the test can be calculated. Furthermore, the corrosion rate can be calculated by multiplying the weight change over an area of ​​1 m². 2 And you can convert it on an hourly basis.

[0080] <Abrasion Resistance> The wear resistance of the alloy member 21 in this embodiment can be evaluated, for example, by the Okoshi wear test, with a specific wear amount of 2 × 10⁻⁶ -7 mm 2 It is desirable that the value be less than / kg.

[0081] For the abrasion test used to evaluate wear resistance, for example, a test piece measuring 25 × 60 × 10 mm (with a combined thickness of 10 mm for the base material and the alloy material) can be taken from the composite alloy member 21 of this embodiment, and both the bottom surface of the base material and the test surface of the alloy material are polished in parallel, and then the test surface is finished with #500 emery paper.

[0082] For example, the wear test conditions could be as follows: use a ring-shaped SCM415 material (Brinell hardness: 163HBW10 / 3000) with a diameter of 30 mm and a sliding width of 3 mm as the mating material, and conduct the test in an unlubricated environment at a speed of 0.79 m / s, a sliding distance of 400 m, and a load of 65 N.

[0083] Specific wear amount W S (mm 2 The weight (kg) is calculated using the width B (mm) of the wear mark, the length b0 (mm) of the wear mark, the diameter D (mm) of the mating ring, the load P (kg), and the sliding distance L (mm), W S =B × b0 3 / (4×D×P×L)···This can be calculated from Equation 2.

[0084] <Product> The manufactured product having at least a portion of the alloy member 21 obtained in this way is not particularly limited, but is suitable, for example, for screws and cylinders for resin injection molding. In this case, even if wear or damage occurs on a part of the surface of the screw or cylinder, it can be easily repaired by forming the alloy layer of the present invention only on the worn or damaged part by build-up. At this time, the alloy member manufactured using the powder used in this embodiment has excellent corrosion resistance and wear resistance. In addition to the layered shape formed on a metal substrate, the manufactured product of the present invention may also be a three-dimensional shape formed on a metal substrate. In the embodiments described later, a member consisting of an alloy layer formed in layers on a metal substrate and a metal substrate is referred to as a composite alloy member, but it goes without saying that a composite alloy member having a metal substrate is also an alloy member of the present invention.

[0085] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. For example, the present invention is not necessarily limited to having all the configurations of the embodiments described above. Some configurations of one embodiment can be replaced with other configurations, some configurations of one embodiment can be added to other forms, and some configurations of one embodiment can be omitted. [Examples]

[0086] The present invention will be described below with reference to examples, but the technical scope of the present invention is not limited thereto.

[0087] (Experiment 1) As examples and comparative examples, raw materials were prepared by weighing and mixing predetermined amounts of each elemental supply material to obtain a Ni-based alloy powder of the desired composition, loading the mixture into a crucible, and melting it by high-frequency induction in a vacuum. The molten alloy was then dropped from a nozzle at the bottom of the crucible and sprayed with high-pressure argon to produce gas atomized powder. This gas atomized powder was classified into 53-106 μm and d 50 A Ni-based alloy powder with a particle size of 80.3 μm was obtained. The composition of the obtained Ni-based alloy powder is shown in Tables 1 and 2. Table 1 shows the content of Cr, Mo, Ta, and Ni, which are components of the Ni-based alloy powder, and Table 2 shows the content of various unavoidable impurities. Note that the Ni content (Bal.) is the remainder after subtracting the content of Cr, Mo, Ta, and unavoidable impurities from the total Ni-based alloy powder, which is considered as 100 mass%.

[0088] [Table 1]

[0089] [Table 2]

[0090] In addition, titanium carbide powder (manufactured by Nippon Shinkinzoku Co., Ltd.) is used as the metal carbide powder. The composition of the titanium carbide powder is shown in Table 3.

[0091] [Table 3]

[0092] Next, using an LMD additive manufacturing apparatus (DMG Mori Seiki Co., Ltd. LASERTEC65 3D Hybrid), a carbide-containing mixed powder, a mixture of Ni-based alloy powder and titanium carbide powder, was supplied to a molten pool formed by laser irradiation on a 100mm x 100mm surface of a 100mm x 100mm x 10.5mm maraging steel (YAG300, manufactured by Proterial Co., Ltd. (YAG is a registered trademark of Proterial Co., Ltd.)) substrate. By rapidly melting and rapidly cooling and solidifying the mixture, a bead with a width of 3mm and a length of 60mm was formed. Multiple layers of this bead were then stacked to form a bead with a width of 3mm and a length of 60mm. A composite alloy member was obtained by forming an alloy layer 60 mm in diameter and approximately 6 mm in height. The carbide-containing mixed powder was supplied by mixing the Ni-based alloy powder and the metal carbide powder (titanium carbide powder) in predetermined proportions according to each example and comparative example. The additive manufacturing conditions, including the mixing ratio of the Ni-based alloy powder and the metal carbide powder (titanium carbide powder), are shown in Tables 4 and 5. Table 4 shows the manufacturing conditions common to each example and comparative example, while Table 5 shows the different manufacturing conditions and mixing ratios for each example and comparative example.

[0093] The layer thickness shown for each example and comparative example in Table 5 was determined by arithmetic mean of the results obtained by measuring the bead height at three points when one layer was fabricated on the base plate under the conditions of each example and comparative example. The number of layers was determined by dividing the planned fabrication height of 6 mm by the arithmetic mean layer thickness and rounding up the decimal part of the result.

[0094] [Table 4]

[0095] [Table 5]

[0096] (Observation of the presence or absence of cracks and voids) The composite alloy members of each example and comparative example shown in Table 5 were cut at the center of the bead formation direction (i.e., the length direction) with a plane perpendicular to the bead formation direction. The cut surface was then embedded in resin and polished to a mirror finish so that it could be observed. First, the cut surface was observed with an optical microscope at an observation magnification (objective lens magnification) of 5x to check for the presence or absence of cracks and voids throughout the entire cut surface.

[0097] Figures 3A to 3E show examples of acquired optical microscope images. Figure 3A is a cross-sectional image of Example 1, Figure 3B is a cross-sectional image of Example 2, Figure 3C is a cross-sectional image of Comparative Example 1, Figure 3D is a cross-sectional image of Comparative Example 2, and Figure 3E is a cross-sectional image of Comparative Example 3. Table 6 shows the presence or absence of cracks and voids and the pass / fail criteria. For the pass / fail criteria, if no cracks or voids were confirmed by visual inspection, it was judged as "OK," and if cracks and / or voids were confirmed by visual inspection, it was judged as "NG."

[0098] By referring to Figures 3A to 3E, the state of voids and cracks within the alloy layer can be confirmed. As shown in Figures 3A, 3B, and 3C, in the alloy layers of composite alloy members with a metal carbide powder mixing ratio of 5 mass% or less (Examples 1, 2, and Comparative Example 1), there were no coarse voids or cracks in the solidification structure, so the pass / fail judgment was OK. On the other hand, as shown in Figure 3D, in the alloy member with a metal carbide powder mixing ratio of 10 mass% (Comparative Example 2), cracks were present in the coarse metal carbide aggregates within the solidification structure, so the pass / fail judgment was NG. Furthermore, as shown in Figure 3E, in the alloy layer of the composite alloy member with a metal carbide powder mixing ratio of 20 mass% (Comparative Example 3), cracks were present in the coarse metal carbide aggregates within the solidification structure, similar to Comparative Example 2, and coarse voids were also present within the solidification structure, so the pass / fail judgment was NG.

[0099] (Observation of coagulated tissue) The solidification structure of the alloy layer of the composite alloy member in each example and comparative example was observed using a scanning electron microscope (SEM) at a magnification of 2000x or 3000x. Elemental mapping images of the solidification structure were also obtained using an EDS (Electronic Data Scanning) system in the same field of view as the SEM. The six elements analyzed were C, Cr, Mo, Ni, Ta, and Ti.

[0100] Figures 4A to 4E show examples of acquired SEM and EDS images. Figure 4A shows the solidification structure and elemental mapping for Example 1, Figure 4B for Example 2, Figure 4C for Comparative Example 1, Figure 4D for Comparative Example 2, and Figure 4E for Comparative Example 3. All SEM images are backscattered electron images.

[0101] By referring to Figures 4A to 4E, you can confirm the morphology of the solidified tissue inside the molded body and the elements, size, and distribution of precipitates.

[0102] As shown in Figures 4A and 4C, in the alloy member with a metal carbide powder mixing ratio of 2.5 mass% (Example 1) and in the alloy layer of the composite alloy member with a metal carbide powder mixing ratio of 0 mass% (no mixing) (Comparative Example 1), it was confirmed that a dendritic structure was present, and that Mo and Ta were concentrated in the dendritic structure.

[0103] As shown in Figure 4B, in the alloy layer of the composite alloy member with a metal carbide powder mixing ratio of 5 mass% (Example 2), a network-like lamellar structure was found, and it was confirmed that Mo, Cr, and Ta were concentrated in this lamellar structure. Furthermore, areas with high concentrations of Ti, Ta, and C were scattered within the solidification structure, confirming the formation of Ti and Ta complex carbides.

[0104] As shown in Figure 4D, in the alloy layer of a composite alloy member with a metal carbide powder mixing ratio of 10 mass% (Comparative Example 2), it was confirmed that Mo-enriched regions were scattered within the solidification structure. Furthermore, it was confirmed that regions with high concentrations of Ti, Ta, and C were scattered within the solidification structure, indicating the formation of Ti and Ta complex carbides. In addition, it was confirmed that the Mo-enriched regions and the regions with high concentrations of Ti, Ta, and C partially overlapped.

[0105] As shown in Figure 4E, in the alloy layer of a composite alloy member with a metal carbide powder mixing ratio of 20 mass% (Comparative Example 3), the precipitates were dendrite-like, and it was confirmed that the precipitate portions had high concentrations of Ti, Ta, Mo, and C, forming complex carbides. Furthermore, it was confirmed that there were Cr and Mo-enriched portions separate from the precipitate portions.

[0106] (Hardness measurement) The hardness of the alloy members was measured at the cross-section of the alloy layer of each example and comparative example composite alloy member using a Vickers hardness tester. The measurement conditions were a Vickers indenter load of 0.2 kg and a residence time of 10 seconds. The hardness was determined from the length of the diagonal of the indentation formed on the measurement surface by the indenter's indentation. Figure 5 shows the hardness measurement locations on the cross-section of the alloy member manufactured using the powder of this embodiment. Seven points (14 points in total) were selected at locations 2.0 mm and 2.5 mm away from the substrate surface to measure the hardness, and the arithmetic mean of the 12 hardness data points, excluding the maximum and minimum values, was calculated. Adjacent hardness measurement points were selected at a distance of 150 μm or more. For the pass / fail judgment of the hardness of each molded body, a value of 350 HV or higher was judged as "OK," and a value below 350 HV was judged as "NG." The results are shown in Table 6.

[0107] [Table 6]

[0108] In the alloy layer of the composite alloy member with a metal carbide powder mixing ratio of 5 mass% (Example 2), the hardness was 432 HV. In the alloy layer of the composite alloy member with a metal carbide powder mixing ratio of 10 mass% (Comparative Example 2), the hardness was 442 HV. In the alloy layer of the composite alloy member with a metal carbide powder mixing ratio of 20 mass% (Comparative Example 3), the hardness was 426 HV. All were hard. As shown in Figures 4B, 4D, and 4E, since carbides are dispersed in the solidified structure, wear resistance can be expected, and the pass / fail judgment was OK. In the alloy layer of the composite alloy member with a metal carbide powder mixing ratio of 2.5 mass% (Example 1), as shown in Figure 4A, carbides could not be confirmed in the solidified structure, but the hardness was 377 HV, which is hard. It is assumed that carbides smaller than the detection limit of EDS are dispersed, and as a result, wear resistance can be expected, so Example 1 was also passed / failed.

[0109] On the other hand, in the alloy layer of the composite alloy member with a metal carbide powder content of 0 mass% (Comparative Example 1), as shown in Figure 4C, no carbides could be observed in the solidification structure. Furthermore, since the hardness was 303HV, which is not particularly hard, it could not be assumed that carbides smaller than the detection limit of EDS were dispersed. Therefore, wear resistance could not be expected, and the pass / fail judgment was rejected.

[0110] In Figure 4A, precipitated carbides cannot be detected within the detection resolution range of the EDS image. Furthermore, in Figure 4B, the area proportion occupied by the detected Ti and Ta complex carbides in the observation field is small, which has the advantage of preventing cracking of the solidified structure and the formation of voids within the structure, as shown in Table 6. In Figure 4A, complex carbides such as Ti and Ta are not detected in the observation field by the EDS image, but hardness is obtained as shown in Table 6, so it is assumed that fine carbides are dispersed in the metallic phase (matrix), and further strengthening is achieved by solid dissolution of a large amount of C in the metallic phase (matrix) (the part other than the carbides). On the other hand, in Figure 4B, complex carbides such as Ti and Ta are detected in the observation field by the EDS image, so strengthening is achieved by solid dissolution of a large amount of C in the metallic phase (matrix) other than the carbides, which has the advantage of making the alloy layer of the composite alloy member hard. Therefore, Examples 1 and 2 are preferred because they do not show defects such as cracks or voids in the solidified structure, and the metallic phase (matrix) is hard.

[0111] (Experiment 2) (Corrosion test) Similar to Experiment 1, Ni-based alloy powders shown in Tables 1 and 2, and metal carbide powders (titanium carbide powders) shown in Table 3 were prepared. Using an LMD (Laser Metal Display) type 3D additive manufacturing apparatus, the carbide-containing mixed powder was supplied to a molten pool formed by laser irradiation on a 100mm x 100mm surface of a 100mm x 100mm x 10.5mm substrate made of plastic mold steel (HPM (HPM is a registered trademark of Proterial Co., Ltd.) 38, manufactured by Proterial Co., Ltd.). The mixture was rapidly melted and then rapidly solidified to form an alloy layer with a width of 35mm, a length of 35mm, and a height of 9-10mm, thereby obtaining a composite alloy member. The additive manufacturing conditions, including the mixing ratio of the Ni-based alloy powder and the metal carbide powders (titanium carbide powders), were as shown in Tables 4 and 7, Example 3. For the raw material powder, a mixed powder of the Ni-based alloy powder and the metal carbide powders (titanium carbide powders) containing 5 mass% of the metal carbide powders (titanium carbide powders) was supplied.

[0112] The bead pitch shown in Table 7 refers to the distance between adjacent beads during the molding process. In Example 3, this was set to 1.5 mm, which is 50% of the laser beam diameter. Considering the layer thickness (the thickness of one layer when layering only in the height direction) of the molded object in Example 2 shown in Table 5, which is 0.242 mm, and the bead pitch of 1.5 mm, the layer thickness in Example 3 was calculated to be 0.365 mm.

[0113] The fabrication process proceeded while measuring the height of the alloy layer, and the process was terminated at layer count 28, when the height exceeded 9 mm, to produce a composite alloy component (Example 3).

[0114] [Table 7]

[0115] A plate-shaped test specimen measuring 25 mm x 25 mm x 3 mm thick was taken from the alloy layer side of the composite alloy member of Example 3 and used as a corrosion test specimen. In addition, a corrosion test specimen of HPM38 material with the same dimensions as Example 3 was prepared as a comparative material for the corrosion test (Comparative Example 4). The surfaces of all test specimens in Example 3 and Comparative Example 4 were wet-polished, finished with #1000 water-resistant emery paper, degreased with acetone and ethanol, and then subjected to the corrosion test.

[0116] For the test specimens of Example 3 and Comparative Example 4, first, the weight before testing was measured. Then, a sulfuric acid aqueous solution, prepared by diluting a special grade sulfuric acid reagent according to JIS K 8951 to 10 mass% with pure water, was heated until the temperature reached 100°C, after which the test specimens were immersed. After 24 hours had elapsed since immersion, the test specimens were removed from the sulfuric acid aqueous solution, and the weight of the test specimens (weight after testing) was measured. The weight change before and after testing was then calculated. Furthermore, regarding the corrosion rate, the weight change was measured over an area of ​​1 m². 2 The values ​​were calculated by converting them to an hourly rate. For the pass / fail determination of the corrosion test, the corrosion rate was 0.3 g·m. -2 ·h -1 The following cases are considered "OK": 0.3g·m -2 ·h -1 Cases greater than this were marked as "NG". The results are shown in Table 8.

[0117] [Table 8]

[0118] As shown in Table 8, the corrosion rate of the specimen in Example 3 was 0.10 g·m -2 ·h -1 Therefore, it showed high corrosion resistance and was deemed acceptable. On the other hand, in Comparative Example 4, the test piece dissolved and disappeared in the corrosive solution during the corrosion test, indicating a corrosion rate of 397.35 g·m -2 ·h -1 The material was deemed to be of the "excessive" quality, and high corrosion resistance could not be achieved, resulting in a rejection.

[0119] (Experiment 3) (Abrasion test) Similar to Experiments 1 and 2, Ni-based alloy powders shown in Tables 1 and 2 and metal carbide powders (titanium carbide powders) shown in Table 3 were prepared. Using an LMD additive manufacturing apparatus, the raw material powders were supplied to a molten pool formed by laser irradiation on a 100mm x 100mm surface of a 100mm x 100mm x 10.5mm substrate made of plastic mold steel (HPM (HPM is a registered trademark of Proterial Co., Ltd.) 38, manufactured by Proterial Co., Ltd.). The molten pools were rapidly melted and then rapidly solidified to form an alloy layer with a width of 33mm, a length of 72mm, and a height of 9-10mm, thereby obtaining a composite alloy member. The additive manufacturing conditions, including the mixing ratio of the Ni-based alloy powder and the metal carbide powders (titanium carbide powders), were the same as those of Example 4 shown in Tables 4 and 9. For the raw material powders, a mixed powder of the Ni-based alloy powder and the metal carbide powders (titanium carbide powders) containing 5 mass% of the metal carbide powders (titanium carbide powders) was supplied.

[0120] [Table 9]

[0121] The bead pitch shown in Table 9 was set to 1.5 mm, the same as in Experiment 2, and the layer pitch was also calculated in the same way as in Experiment 2. Three alloy members were prepared as test specimens for wear testing. The fabrication process proceeded while measuring the height of the alloy layer of each composite alloy member, and the fabrication was terminated at layer counts 24-26, where the height exceeded 9 mm, to produce the fabricated body (Example 4).

[0122] From the molded body of Example 4, a sample was taken with dimensions of 25 mm in width, 60 mm in length, and 10 mm in thickness (approximately 5 mm for the molded portion and approximately 5 mm for the base material). Both sides of the 25 mm x 60 mm surface of the sampled test piece were parallel polished, and only the surface used for the abrasion test (one side of the 25 mm x 60 mm (two surfaces)) was finished with #500 water-resistant emery paper and used as a test piece for the Okoshi abrasion test. In addition, as a comparative material for the abrasion test, an abrasion test piece of SKD61 material (DAC manufactured by Proterial Co., Ltd. (DAC is a registered trademark of Proterial Co., Ltd.)) with the same dimensions as in Example 4 was prepared (Comparative Example 5). Parallel polishing and finishing were performed in the same manner as in Example 4, and it was similarly used as a test piece for the Okoshi abrasion test. For the abrasion test specimen, an SCM415 material (hardness: 163HBW10 / 3000) was prepared, with the sliding surface being the side surface of a cylinder with a diameter of 30 mm and a width of 3 mm, and was subjected to the Okoshi abrasion test.

[0123] The conditions for the Okoshi abrasion test were a sliding speed of 0.79 m / sec, a sliding distance of 400 m, a sliding load of 65 N, and an unlubricated sliding atmosphere. Sliding tests were performed at three different locations on each test specimen. After the tests, the wear width was measured at five locations on the sliding marks formed in each test, and the specific wear amount was calculated from the arithmetic mean of these measurements for each test. The average specific wear amount for each specimen was also calculated by arithmetic mean of the specific wear amounts from the three different test locations. The pass / fail criteria for the abrasion test were based on a specific wear amount of 2 × 10⁻⁶. -7 mm 2 If it is less than / kg, it is "OK", 2 x 10 -7 mm 2 Values ​​greater than / kg were classified as "NG". The results are shown in Table 10.

[0124] [Table 10]

[0125] As shown in Table 10, in Example 4, the specific wear amount was 2 × 10 in all test specimens. -7 mm 2 The specific wear amount was less than 2 × 10⁻⁶ / kg, indicating high wear resistance, so it was deemed acceptable. On the other hand, in Comparative Example 5, the specific wear amount was 2 × 10⁻⁶. -7 mm 2 The value was greater than / kg, and high abrasion resistance could not be achieved, so the pass / fail judgment was rejected. [Explanation of Symbols]

[0126] 1…Additive manufacturing equipment, 3…Powder supply nozzle, 5…Focusing lens, 7…Protective lens, 9…Laser beam, 11…Powder, 13…Molten pool, 15…Alloy layer, 17…Substrate, 19…Mixed layer, 21…Alloy component, 31…Hardness measurement point

Claims

1. A Ni-based alloy forming powder consisting of, by mass%, Cr: 14% to 24%, Mo: 14% to 24%, Ta: 1.0% to 2.5%, with the remainder being Ni and unavoidable impurities, Prepare a metal carbide powder consisting of at least one metal element selected from Ta, Nb, Ti, V, and Zr, and C. A method for manufacturing an alloy member, comprising mixing the Ni-based alloy forming powder and the metal carbide powder such that the mass ratio of the metal carbide powder to the total mass of the Ni-based alloy forming powder and the metal carbide powder is greater than 0% and less than 10%, thereby obtaining a carbide-containing mixed powder, and irradiating the carbide-containing mixed powder with energy rays to melt and solidify it to form an alloy layer.

2. The method for manufacturing an alloy member according to claim 1, characterized in that the alloy layer is formed by solidification on a metal substrate, and the solidification structure of the alloy layer has a dendritic crystalline structure and metal carbides.

3. The method for manufacturing an alloy member according to claim 1 or 2, characterized in that the metal carbide powder contains, by mass, 15% to 25% of C and 75% to 85% of Ti.

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