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EP-4129533-B1 - ALLOY, ALLOY POWDER, ALLOY MEMBER, AND COMPOSITE MEMBER

EP4129533B1EP 4129533 B1EP4129533 B1EP 4129533B1EP-4129533-B1

Inventors

  • SHIRATORI, HIROSHI
  • SHINAGAWA, Kazuya
  • KUWABARA, KOUSUKE
  • KOSEKI, Shuho

Dates

Publication Date
20260506
Application Date
20210331

Claims (7)

  1. An alloy comprising, by mass%: Cr: 18 to 22%; Mo: 18 to 28%; Ta: 1.5 to 57%; C: 1.0 to 2.5%; Nb: 0 to 42%; Ti: 0 to 15%; V: 0 to 27%; Zr: 0 to 29%; P: 0 to 0.01 %; S: 0 to 0.01 %; N: 0 to 0.003%; and a remainder consisting of Ni and unavoidable impurities, where a molar ratio of (Ta + 0.7Nb + Ti + 0.6V + Zr) / C = 0.5 to 1.5 is satisfied.
  2. An alloy powder for additive manufacturing according to a powder bed fusion method, PBF, or a directed energy deposition method, DED, the alloy powder comprising, by mass%: Cr: 18 to 22; Mo: 18 to 28%; Ta: 1.5 to 57%; C: 1.0 to 2.5%; Nb: 0 to 42%; Ti: 0 to 15%; V: 0 to 27%; Zr: 0 to 29%; P: 0 to 0.01 %; S: 0 to 0.01 %; N: 0 to 0.003%; and a remainder consisting of Ni and unavoidable impurities, where a molar ratio of (Ta + 0.7Nb + Ti + 0.6V + Zr) / C = 0.5 to 1.5 is satisfied.
  3. The alloy powder according to claim 2, wherein d 50 , which is an average particle size when an integrated value by laser diffraction/scattering type particle size distribution measurement is 50% by volume, is 5 to 500 µm.
  4. An alloy member which is a product additively manufactured according to a powder bed fusion method, PBF, or a directed energy deposition method, DED, or a cast and has a solidification structure, comprising, by mass%: Cr: 18 to 22%; Mo: 18 to 28%; Ta: 1.5 to 57%; C: 1.0 to 2.5%; Nb: 0 to 42%; Ti: 0 to 15%; V: 0 to 27% Zr: 0 to 29%; P: 0 to 0.01 %; S: 0 to 0.01 %; N: 0 to 0.003%; and a remainder consisting of Ni and unavoidable impurities, where a molar ratio of (Ta + 0.7Nb + Ti + 0.6V + Zr) / C = 0.5 to 1.5 is satisfied, wherein the solidification structure is a dendrite-like crystal structure having a metal phase having a face-centered cubic structure and carbides.
  5. The alloy member according to claim 4, wherein Mo in the metal phase is 15% by mass or more.
  6. A composite member comprising: a base material; and an alloy layer provided on a surface of the base material, wherein the alloy layer which is a product additively manufactured according to a powder bed fusion method, PBF, or a directed energy deposition method, DED, and has a solidification structure, includes, by mass%, Cr: 18 to 22%, Mo: 18 to 28%, Ta: 1.5 to 57%, C: 1.0 to 2.5% Nb: 0 to 42%, Ti: 0 to 15%, V: 0 to 27%, Zr: 0 to 29%, P: 0 to 0.01 %; S: 0 to 0.01 %; N: 0 to 0.003%; and a remainder consisting of Ni and unavoidable impurities, where a molar ratio of (Ta + 0.7Nb + Ti + 0.6V + Zr) / C = 0.5 to 1.5 is satisfied, and wherein the solidification structure is a dendrite-like crystal structure having a metal phase having a face-centered cubic structure and carbides.
  7. The composite member according to claim 6, which is a screw for injection molding or a cylinder for injection molding.

Description

Technical Field The present invention relates to an alloy, an alloy powder, an alloy member, and a composite member which are excellent in corrosion resistance and wear resistance, have crack resistance, and are suitable for an additive manufacturing method and the like. Background Art An injection molding machine is provided with a screw that injects a melted resin into a mold while kneading the melted resin, in a cylinder that heats and melts an input resin. Since corrosive gas such as sulfurized gas may be generated when the resin is melted, the screw or cylinder for injection molding is required to have corrosion resistance to withstand the corrosive gas. Further, since glass fiber, carbon fiber and the like are added to the resin at the time of molding the fiber reinforced plastic, wear resistance, that is, hardness is also required. In the related art, as an alloy having excellent corrosion resistance and high hardness, a Ni-based alloy (Ni-Cr-Mo-based alloy) having the highest amount of Ni by mass ratio and having the next highest amounts of Cr and Mo is known. JP-A-2015-160965 (PTL 1) describes a Ni-based alloy containing more than 18% by mass and less than 21% by mass Cr, more than 18% by mass and less than 21% by mass Mo, Ta, Mg, N, Mn, Si, Fe, Co, Al, Ti, V, Nb, B, and Zr, and having excellent hot forgeability and corrosion resistance. However, PTL 1 does not disclose the hardness of this Ni-based alloy. According to the investigation conducted by the present inventors, it has been confirmed that the hardness of the Ni-based alloy to which Cr and Mo are added is approximately 20 to 30 HRC. At this level of hardness, wear resistance is insufficient in a case of being applied to screws or cylinders for injection molding. In general, the wear resistance of a metal material increases when hard particles are dispersed in a crystal structure. JP-A-2014-221940 (PTL 2) discloses a Ni-based boride-dispersed corrosion-resistant and wear-resistant alloy in which a hard phase mainly composed of boride is dispersed in a Ni-based alloy to which Cr and Mo are added. Further, JP-A-5-156396 (PTL 3) discloses a Ni-based alloy for metalizing, in which carbides formed of at least one of Ti, Zr, Nb, V, and Ta are dispersed in a Ni-based alloy to which Cr and Mo are added. Citation List Patent Literature PTL 1: JP-A-2015-160965PTL 2: JP-A-2014-221940PTL 3: JP-A-5-156396 A Ni-based alloy powder and a Ta-based hard alloy related to the present invention are disclosed in WO 2019/049594 A1 and GB 378 055 A, respectively. Summary of Invention Technical Problem The wear resistance of the alloy can be improved by a method of dispersing borides and carbides, as described in PTL 2 and PTL 3. However, when the amount of boride or carbide is extremely large, the corrosion resistance is lowered due to the intergranular segregation or the formation of a local cell of Cr. Further, depending on the amount of dispersion or the form of dispersion, the hardness becomes extremely high and the alloy becomes brittle. In order to obtain an alloy having excellent corrosion resistance or wear resistance, it is necessary to optimize the addition amount or addition ratio of each element in consideration of element distribution, and it is required to achieve both corrosion resistance and wear resistance without breaking the balance. When the hardness of the Ni-based alloy is low, wear resistance is insufficient in a case of being applied to screws or cylinders for injection molding. Therefore, it is desired to further increase the hardness of such alloys. Further, the Ni-based alloy of the related art in which borides or carbides are dispersed is often processed and molded by a sintering method or a hot isostatic press (HIP) method. However, the sintering method and the HIP method are manufacturing methods having a low degree of freedom in the shape of a workpiece. When the sintering method or the HIP method is used, it is difficult to manufacture a product having a complicated shape, and the application of the product is limited. Therefore, a more practical manufacturing method is required. In addition to the sintering method or the HIP method, there is also a casting method or an additive manufacturing (AM) method as a method of processing metal materials. Since the degree of freedom in the shape of the workpiece is high, these manufacturing methods are suitable for manufacturing objects having complicated shapes. However, the casting method or the additive manufacturing method involves melting and solidification (hereinafter, may be referred to as melting/solidification) of a metal material. When these manufacturing methods are used for dispersion-reinforced Ni-based alloys, a large thermal stress is generated during melting/solidification, and thus cracks are likely to occur. In general, it can be said that a carbide dispersive alloy can be manufactured more easily than a boride dispersive alloy because thermal refining is possible. However