Material for stainless steel modeling, stainless steel modeling material, and method for producing stainless steel modeling material

Abstract

To provide a shaping material excellent in the balance between strength and toughness.SOLUTION: A shaped stainless steel material having a composition containing, by mass%, C:0.070% or less, Si: 0.30% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, Cr: 14.0% or more and 17.5% or less, Ni: 3.0% or more and 6.0% or less, V: 0.01% or more and 0.10% or less, N: 0. 100% or less, Mo: 0.03% or more and 0.10% or less, Cu: 2.5% or more and 5.0% or less, and Nb: 0.15% or more and 0.45% or less, with the balance being inevitable impurities and Fe, and satisfying the following Formula (1): Nieq ≥ 0. 923Creq - 8.537 (1) SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a stainless steel molding material used in molding, a stainless steel molding material using said material, and a method for manufacturing said stainless steel molding material. [Background technology]

[0002] In recent years, the application of metal additive manufacturing (hereinafter referred to as AM) technology using 17Cr martensitic stainless steel powder as a raw material has been progressing. The application of AM technology makes it possible to manufacture parts with more complex shapes than conventional technologies, and is therefore expected to provide added value such as shorter lead times and reduced costs, in addition to higher functionality due to increased design freedom. 17Cr martensitic stainless steel is mainly used in the aerospace and industrial machinery fields, where high strength and toughness are required. For example, Patent Document 1 describes a metal additive manufacturing (AM) material made of 17Cr martensitic stainless steel.

[0003] Patent Document 1 describes a stainless steel additive manufacturing material having a predetermined composition and a structure containing 45% by volume or more of a martensite phase and 25% by volume or less of an austenite phase. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-6584

[0005] [Non-Patent Document 1] S. Sabooni, A. Chabok, SC Feng, H. Blaauw, TC Pijper, HJ Yang and YT Pei: Addit. Manuf., 46 (2021) 102176.,p.5 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the AM material of Patent Document 1 does not have sufficient yield strength while maintaining good toughness. In addition, it has poor hardenability and the presence of 10% or more of residual ferrite phase deteriorates mechanical properties, so it does not have a sufficient balance of strength and toughness. The present invention has been made in light of the above circumstances, and has as its object to obtain an image formation excellent in both toughness and strength. [Means for solving the problem]

[0007] A stainless steel molding material according to one embodiment of the present disclosure has specific components and a composition in which Nieq (Ni equivalent) and Creq (Cr equivalent) satisfy Nieq≧0.923Creq−8.537. In one embodiment, the stainless steel shape has an as-shaped martensitic structure. In one embodiment, a method for manufacturing a stainless steel shaped material involves creating a shaped material having a martensitic structure using a shaped material of the above-mentioned composition, and then performing solution heat treatment and aging treatment to produce a stainless steel shaped material having a martensitic structure. [Effects of the Invention]

[0008] According to the present invention, a shaped material having a martensite structure can be obtained even in the as-shaped state, and excellent properties in toughness and strength can be obtained. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the structure of the molding material of the present disclosure and the comparative molding material according to the relationship between Nieq and Creq. [Figure 2A] FIG. 2 is a diagram showing one condition of the solution heat treatment in the example. [Figure 2B] FIG. 2 is a diagram showing one condition of the solution heat treatment in the example. [Figure 2C] FIG. 2 is a diagram showing one condition of aging heat treatment in an example. [Figure 3]1 is a photograph in place of a drawing showing the structure of a test material in an example. [Figure 4] 1 is a graph showing the relationship between strength and toughness of test materials in Examples. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described. (Manufacturing of modeling materials) The alloy contains, in mass%, C: 0.070% or less, Si: 0.30% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, Cr: 14.0% or more and 17.5% or less, Ni: 3.0% or more and 6.0% or less, V: 0.01% or more and 0.10% or less, N: 0.100% or less, Mo: 0.03% or more and 0.10% or less, Cu: 2.5% or more and 5.0% or less, Nb: 0.15% or more and 0.45% or less, with the remainder consisting of inevitable impurities and Fe, and is prepared to have a composition that satisfies the following formula (1). Nieq≧0.923Creq - 8.537 …(1) where Nieq and Creq are calculated using equations (2) and (3). Nieq=(mass%Ni)+30(mass%C)+0.5(mass%Mn)+0.3(mass%Cu)+25(mass%N...(2) Creq=(mass%Cr)+2(mass%Si)+1.5(mass%Mo)+5(mass%V)+1.75(mass%Nb)+1.5(mass%Ti)+5.5(mass%Al)...(3)

[0011] The component composition of the stainless steel molding material of the present disclosure and the reasons for its limitations will be explained below.

[0012] C: 0.070% or less C must be kept low because it improves the hardness of the as-formed AM material and promotes cracking during fabrication. Therefore, the content must be 0.070% or less by mass (hereinafter simply referred to as "%." Unless otherwise specified in this specification, "%" represents mass %). It is more preferably 0.050% or less, and even more preferably 0.025% or less.

[0013] Si:0.30% or less Si combines with O in the AM material to form Si-based oxides. These oxides become the starting point for fracture during tensile tests and stress loading, significantly reducing toughness, so the Si content must be kept low. For this reason, the Si content is set to 0.30% or less, more preferably 0.25% or less, and even more preferably 0.21% or less.

[0014] Mn: 1.0% or less Mn is an element that combines with S to form MnS, which reduces mechanical properties and corrosion resistance. Therefore, the Mn content is set to 1.0% or less, more preferably 0.8% or less, and even more preferably 0.6% or less.

[0015] P:0.040% or less P is an element that tends to segregate at grain boundaries and reduces mechanical properties. Therefore, the P content is set to 0.040% or less, more preferably 0.030% or less, and even more preferably 0.025% or less.

[0016] S: 0.030% or less S is an element that forms MnS and reduces mechanical properties. Therefore, the content is set to 0.030% or less, more preferably 0.005% or less, and even more preferably 0.002% or less.

[0017] Cr:14.0% or more and 17.5% or less Cr is an element that forms a passive film on the surface of AM materials, contributing to improved corrosion resistance. A Cr content of 14.0% or less cannot ensure the desired corrosion resistance. On the other hand, a large amount of Cr increases Creq, changing the as-formed structure into a coarse ferrite structure, or leaving ferrite after solution treatment, preventing the formation of a uniform martensite structure. Therefore, the Cr content is set to 14.0% or more and 17.5% or less. For the same reasons, the lower limit is preferably 15.0% and the upper limit is preferably 16.0%. An upper limit of 15.3% is even more preferable.

[0018] Ni: 3.0% or more and 6.0% or less Ni is an element that increases Nieq and transforms the as-formed structure into fine martensite. It also has the effect of increasing the adhesion of the oxide film of Cr oxide, improving corrosion resistance. On the other hand, a large amount of Ni increases the retained austenite fraction of the AM material and reduces the martensite fraction, thereby reducing strength. For this reason, the Ni content is set to 3.0% or more and 6.0% or less. For the same reason, the lower limit is preferably 4.5% and the upper limit is preferably 5.5%. Even more preferably, the lower limit is 4.8% and the upper limit is 5.2%.

[0019] V: 0.01% or more and 0.10% or less V not only contributes to improving strength as a solid solution element, but also bonds with C and N to form fine V carbonitrides, preventing grain coarsening during heat treatment and contributing to the refinement of the martensite structure. To achieve this effect, a V content of 0.01% or more is required. On the other hand, a large amount of V increases Creq, changing the as-formed structure to a ferrite structure, or forms coarse V carbonitrides, degrading mechanical properties. Therefore, the V content is set to 0.01% or more and 0.10% or less. For the same reasons, the lower limit is preferably 0.03% and the upper limit is preferably 0.08%. More preferably, the lower limit is 0.04% and the upper limit is 0.06%.

[0020] N: 0.100% or less If N is contained in large amounts, it forms NbCrN (Z phase) and nitrides, which reduces toughness. Therefore, the N content is set to 0.100% or less, preferably 0.040% or less, and more preferably 0.025% or less.

[0021] Mo: 0.03% or more and 0.10% or less Mo has the effect of improving the toughness and hardenability of AM materials. To achieve these effects, a Mo content of 0.03% or more is required. On the other hand, a large amount of Mo increases Creq, changing the as-formed structure to ferrite. For this reason, the Mo content is set to 0.03% or more and 0.10% or less. For the same reason, the lower limit is preferably 0.05% and the upper limit is preferably 0.08%. A more preferable lower limit is 0.06%.

[0022] Cu: 2.5% or more and 5.0% or less Cu forms fine precipitates during aging heat treatment, improving strength. However, if the Cu content is less than 2.5%, this effect is not fully achieved, resulting in insufficient 0.2% yield strength. However, if the Cu content exceeds 5.0%, Cu does not dissolve sufficiently during solution treatment, resulting in coarse Cu precipitates, which reduces mechanical properties. For this reason, the Cu content is set to 2.5% or more and 5.0% or less. Preferably, it is 3.0% or more. More preferably, it is 3.6% or more.

[0023] Nb: 0.15% or more and 0.45% or less Nb combines with C and N to precipitate as fine carbonitrides, preventing grain coarsening during heat treatment and contributing to the refinement of the martensite structure. To achieve this effect, a Nb content of 0.15% or more is required. On the other hand, a large amount of Nb changes the as-formed structure to a ferrite structure, and the coarse carbonitrides further degrade mechanical properties. Therefore, the Nb content is set to 0.15% or more and 0.45% or less. For the same reasons, the lower limit is preferably 0.20% and the upper limit is preferably 0.35%. The upper limit is more preferably 0.33%.

[0024] (unavoidable impurities) In the alloy composition of the present disclosure, the balance consists of inevitable impurities and Fe. The inevitable impurities may include Al, Ti, O, etc., and the contents of Al, Ti, and O are exemplified below. Note that the inevitable impurities are not limited to the following components.

[0025] Al: 0.100% or less If Al is contained in large amounts, it forms coarse oxides and reduces toughness. Therefore, the Al content is preferably 0.100% or less, more preferably 0.010% or less, and even more preferably 0.005% or less.

[0026] Ti: 0.05% or less If Ti is contained in a large amount, it forms coarse oxides and reduces toughness. Therefore, the Ti content is preferably 0.05% or less, more preferably 0.03% or less, and even more preferably 0.01% or less.

[0027] O: 0.100% or less O combines with other elements in the AM material to form coarse oxides, which reduces toughness. For this reason, the O content is preferably 0.100% or less, more preferably 0.050% or less, and even more preferably 0.030% or less.

[0028] Nieq≧0.923Creq - 8.537 …(1) Here, Nieq and Creq are calculated using equations (2) and (3). Nieq=(mass%Ni)+ 30(mass%C)+0.5(mass%Mn)+0.3(mass%Cu)+25(mass%N) …(2) Creq=(mass%Cr)+2(mass%Si)+1.5(mass%Mo)+5(mass%V)+1.75(mass%Nb)+1.5(mass%Ti)+5.5(mass%Al) …(3) However, equations (2) and (3) are taken from Non-Patent Document 1.

[0029] AM materials that satisfy formula (1) have a fine martensite structure as-formed, and exhibit excellent toughness. The martensite structure preferably has an average grain size of less than 10 μm. If the average crystal grain size of the as-formed structure is 10 μm or more, it is not possible to obtain a martensitic structure with an average crystal grain size of less than 15 μm after solution heat treatment, making it difficult to obtain a sufficient balance of strength and toughness.

[0030] The material can be melted by a conventional method, and can be prepared in the form of a block or powder, and is used as a molding material for molding.

[0031] (Production of molding materials) The above-mentioned molding material can be used for metal additive manufacturing, metal powder injection molding, thermal spray surface treatment, etc.

[0032] For materials having the component amounts disclosed herein (those that satisfy formula (1) and those that do not), the as-formed structural morphology is shown in Figure 1 in relation to Creq and Nieq, which relate to hardenability. As is clear from FIG. 1, in the relationship between Nieq and Creq, when Nieq is equal to or greater than (0.923Creq-8.537), the structure is a martensite structure, and when Nieq is less than (0.923Creq-8.537), the structure is a mixed phase of martensite and ferrite or a ferrite phase, and the above formula is significant. Note that a martensite structure is considered to have an area fraction of 85% or more.

[0033] In metal additive manufacturing, for example, a block or powder of stainless steel molding material is prepared as a raw material. The preparation of the raw material is not particularly limited, and can be carried out by any appropriate method. The raw material is melted and then additively manufactured. The manufacturing process can be performed without the need for any special methods, and methods such as sending the molten raw material through a nozzle or melting the material with a laser or other device to create the desired shape can be used. The manufacturing material can be left to cool, or, if necessary, can be rapidly cooled using a cooling device. Regardless of the cooling method, the resulting manufacturing material has a martensitic structure and a fine grain structure with an average diameter of less than 10 μm. This result is due to the composition of the manufacturing material.

[0034] The shaped material can be subjected to heat treatment if desired, and examples of heat treatment include solution heat treatment and aging heat treatment. The solution heat treatment may be carried out, for example, at a temperature of 950°C to 1150°C for 0.5 to 10 hours, followed by cooling to room temperature at a rate of 90°C / h or more. The conditions for the aging heat treatment include a heat treatment method in which the tempering parameter P is 17,600 or more and 19,500 or less. Here, P is calculated using formula (4), where T is the temperature (K) and t is the heat treatment time (h). P = T (log(t) + 20) ... (4) After the solution heat treatment and aging heat treatment, the structure of the shaped material has a martensite structure, preferably with an area fraction of 85% or more, and more preferably with an area fraction of 90%. The shaped material has an average grain size of less than 15 μm. If the average grain size throughout the structure is 15 μm or more or the martensite structure fraction is less than 85%, the tensile properties and toughness will decrease.

[0035] Heat-treated molding materials have excellent strength and toughness, and the balance between these properties satisfies the following formula (5). In the range of 500≦0.2%YS≦1200, E (J / cm 2 )≧-0.167(0.2%YS)+260 …(5) However, 0.2% YS is the yield strength (MPa) at room temperature in accordance with JIS Z 2241:2022, and E is the absorbed energy (J / cm) in a Charpy impact test at 20°C in accordance with JIS Z2242:2022. 2 ) Preferably, E (J / cm 2 )≧-0.167(0.2%YS)+300. More preferably, the 0.2% YS is in the range of 600 to 1150 MPa. More preferably, after solution heat treatment and aging heat treatment, the 0.2% yield strength is 700 MPa or more and the absorbed energy is 150 J / cm 2 That's all.

[0036] Furthermore, it is desirable that the oxides in the shaped body after the solution heat treatment and aging heat treatment have an area ratio of less than 0.2% and an average diameter of the oxides of less than 80 nm. Oxides formed by Si and other elements reduce toughness, so it is desirable to set an upper limit on the area ratio, with the average diameter preferably being less than 80 nm. Coarse oxides are more likely to cause cracks. [Example]

[0037] Hereinafter, a method for manufacturing a martensitic steel shaped material by metal additive manufacturing will be described in detail using examples and comparative examples.

[0038] A molding material having the composition shown in Table 1 was prepared and passed through a known electric sieve to classify it into powder having a particle size distribution of 20 to 53 μm. Using a commercially available laser additive manufacturing device (powder bed fusion method), six types of test materials A to F were manufactured from the stainless steel metal powder described above. The manufacturing parameters were: power: 245 W, scanning speed: 910 mm / sec, layer pitch: 30 μm, hatch pitch: 100 μm. The compositions of test materials A and B have a Si content of 0.30% or less and satisfy formula (1) (invention examples). The composition of test material C has a Si content of more than 0.30% and does not satisfy formula (1) (comparison example). The compositions of test materials D to F have a Si content of more than 0.30%, but satisfy formula (1) (comparison example).

[0039] [Table 1]

[0040] Each test material was subjected to the solution heat treatment (i) shown in Figure 2A, followed by the aging heat treatment shown in Figure 2C and Table 2. For test material C only, two types were prepared: one that had been subjected to the solution heat treatment (i) and one that had been subjected to the solution heat treatment (ii) shown in Figure 2B, which had an additional heat treatment step, and then each was subjected to the aging treatment shown in Figure 2C.

[0041] [Table 2]

[0042] Each test material as-formed, each test material after solution heat treatment (after solution heat treatment, aging heat treatment) before ), and specimens were taken from each test material after solution heat treatment and aging treatment (after solution heat treatment + aging heat treatment) so that the cross section perpendicular to the manufacturing direction served as the observation surface. Each specimen was then polished using diamond paste and colloidal silica suspension. Microstructure observation was then performed using a scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) (field of view: 400 μm × 600 μm), and the martensite phase fraction and average grain size (area basis) were calculated using EDAX OIM Analysis™ software. When calculating the structure fraction of the martensite phase, the accelerating voltage of the SEM was 15 kV, the magnification of the EBSD analysis was 3000 times, and the step size was 0.07 μm. When calculating the average grain size, the SEM acceleration voltage was 15 kV, the EBSD analysis magnification was 200x, and the step size was 1 μm. The grain size r was calculated using equation (6) from the area A of the grain image defined by the grain boundaries with a misorientation of 15° or more, and the average value of r of the grains in the grain image was taken as the average grain size. r=(4A / π)^(1 / 2) …(6) Furthermore, the area ratio and average diameter of oxides were investigated from the backscattered electron images of the SEM using WinROOF™ image analysis software. The SEM accelerating voltage was 15 kV, and the magnification of the SEM images was 5000x.

[0043] Next, for each test material after solution heat treatment and aging treatment, a tensile test piece with a parallel portion having a diameter of 6 mm was prepared so that the tensile direction was perpendicular to the forming direction, and a tensile test was carried out at room temperature in accordance with JIS Z 2241:2022. Two or three Charpy test specimens were taken from each test material and subjected to a Charpy impact test at 20°C in accordance with JIS Z 2242:2022. For the Charpy impact test, a test specimen was used that was 55 mm long, had a square cross section with a side length of 10 mm, and had a V-notch 2 mm deep in the center. The direction of the impact was parallel to the direction of fabrication. After the test, the average absorbed energy was calculated using a square cross section of 0.8 cm2, which is the cross section of the test specimen. 2 Divide by the impact value (J / cm 2 ) was decided.

[0044] Each test material as-formed and each test material after solution heat treatment (after solution heat treatment, aging heat treatment) before The grain map (micrograph) of each specimen is shown in Figure 3. The average grain size of each specimen obtained from Figure 3 is shown in Table 3. The above grain map was obtained from the results of EBSD analysis and shows a crystal grain image defined as grain boundaries with a misorientation of 15° or more.

[0045] In Comparative Examples 1 and 2, coarse ferrite with an average grain size of 10 μm or more was observed in the as-formed specimens. On the other hand, fine martensite was observed in the other specimens. After solution treatment, coarse martensite with an average grain size of 15 μm or more was observed in Comparative Example 1, in which the grain morphology of the as-formed structure remained, while fine martensite was observed in all other specimens. From the above, it can be seen that specimens with a composition satisfying formula (1) become fine martensite after solution treatment. Furthermore, a comparison between Comparative Examples 1 and 2 revealed that a fine martensite structure can be obtained by increasing the number of solution treatment steps. The grain map after aging treatment showed almost no change compared to before aging treatment, so it is omitted.

[0046] The 0.2% proof stress and impact value of each test material after solution treatment and aging treatment are shown in Table 3. The 0.2% proof stress (MPa) and impact value (J / cm 2) is shown in Figure 4. The test material of the present disclosure satisfies formula (5), and it has become clear that formula (5) is significant. Formula (5) shows a straight line indicating the boundary between the region of 0.2% yield strength and impact value shown by known materials and the region above this, and in the examples, the 0.2% yield strength (0.2% YS; MPa) at room temperature and the absorbed energy E (J / cm) in a Charpy impact test at 20°C are 2 ) trend. E≧-0.167(0.2%YS)+260…(5) In addition, the embodiment E≧−0.167(0.2% YS)+300 (5A) This relational expression (5A) shows a tendency that is closer to the numerical values ​​of the 0.2% proof stress and absorbed energy of the examples. The relationship between yield strength and impact value can be changed by changing the heat treatment conditions. For example, increasing the solution temperature and increasing the grain size tends to decrease both the 0.2% YS and impact value. Furthermore, the relationship between yield strength and impact value can be changed by changing the composition, etc., within the composition range. For example, reducing the content of Cu, a major component that affects strength, decreases yield strength. Changing the oxide area ratio and average oxide diameter also affects the relationship between yield strength and impact value. These effects make it possible to satisfy equation (5) and even equation (5A).

[0047] In Comparative Example 1, the area ratio and average grain size of Si-based oxides were high due to the high Si and O contents. In addition, since Nieq did not satisfy formula (1), the structure after solution heat treatment and aging heat treatment became coarse martensite with an average grain size of 15 μm or more. Therefore, the strength-toughness balance was the worst. In Comparative Example 2, Nieq did not satisfy the formula (1), but the structure was refined by increasing the number of heat treatment steps. As a result, the strength-toughness balance was improved compared to Comparative Example 1. However, the area ratio and average particle size of the Si-based oxides were high, so the strength-toughness balance was poor. In Comparative Examples 3 to 5, Nieq satisfied the formula (1), and thus the structure after the solution heat treatment and the aging heat treatment became fine martensite. However, because the Si and O contents were high, the area ratio and average grain size of Si-based oxides were high, and the strength-toughness balance was poor. In contrast, Inventive Examples 1 and 2 satisfied the conditions of the present invention and therefore had an excellent balance of strength and toughness on the low strength side (a region in which the 0.2% proof stress is 1200 MPa or less). In this example, a structure having a martensite structure with an area fraction of 85% is shown as a martensite structure.

[0048] [Table 3]

[0049] As described above, by controlling the component composition and Si content in the present disclosure, a martensite structure can be obtained in the as-formed state, and by increasing the fine martensite fraction to 85% or more through heat treatment, the martensite and oxides can be further refined, thereby providing a powder and a shaped body with an excellent balance of strength and toughness.

Claims

1. A stainless steel forming material containing, by mass%, C: 0.070% or less, Si: 0.30% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, Cr: 14.0% or more and 17.5% or less, Ni: 3.0% or more and 6.0% or less, V: 0.01% or more and 0.10% or less, N: 0.100% or less, Mo: 0.03% or more and 0.10% or less, Cu: 2.5% or more and 5.0% or less, and Nb: 0.15% or more and 0.45% or less, with the remainder consisting of inevitable impurities and Fe, and having a composition that satisfies the following formula (1): Nieq≧0.923Creq - 8.537...(1) where Nieq and Creq are calculated using equations (2) and (3). Nieq=(mass%Ni)+30(mass%C)+0.5(mass%Mn)+0.3(mass%Cu)+25(mass%N)...(2) Creq = (mass % Cr) + 2 (mass % Si) + 1.5 (mass % Mo) + 5 (mass % V) + 1.75 (mass % Nb) + 1.5 (mass % Ti) + 5.5 (mass % Al)... (3).

2. A stainless steel forming material containing, by mass%, C: 0.070% or less, Si: 0.30% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, Cr: 14.0% or more and 17.5% or less, Ni: 3.0% or more and 6.0% or less, V: 0.01% or more and 0.10% or less, N: 0.100% or less, Mo: 0.03% or more and 0.10% or less, Cu: 2.5% or more and 5.0% or less, Nb: 0.15% or more and 0.45% or less, with the balance consisting of inevitable impurities and Fe, and having a composition that satisfies the following formula (1), and whose structure in the as-formed state is martensitic. Nieq≧0.923Creq - 8.537...(1) where Nieq and Creq are calculated using equations (2) and (3). Nieq=(mass%Ni)+30(mass%C)+0.5(mass%Mn)+0.3(mass%Cu)+25(mass%N)...(2) Creq = (mass % Cr) + 2 (mass % Si) + 1.5 (mass % Mo) + 5 (mass % V) + 1.75 (mass % Nb) + 1.5 (mass % Ti) + 5.5 (mass % Al)... (3).

3. 3. The stainless steel shaped material according to claim 2, wherein the average crystal grain size is less than 10 μm.

4. 3. The stainless steel shaped material according to claim 2, wherein the material is subjected to a solution heat treatment under the conditions of holding at a temperature of 950°C to 1150°C for 0.5 to 10 hours, followed by cooling to room temperature at a rate of 90°C / h or more, and then subjected to an aging heat treatment under the conditions of a tempering parameter P of 17,600 to 19,500, resulting in a martensitic structure. where P is calculated using formula (4), T is the temperature (K), and t is the heat treatment time (h). P=T(log(t)+20)...(4).

5. The stainless steel shaped material according to claim 4, wherein the average crystal grain size after the solution heat treatment and the aging heat treatment is less than 15 μm.

6. 6. The stainless steel shaped material according to claim 4, wherein the oxides in the shaped body after the solution heat treatment and the aging heat treatment have an area ratio of less than 0.2% and an average diameter of the oxides of less than 80 nm.

7. 6. The stainless steel shaped material according to claim 4, wherein the shaped body after the solution heat treatment and the aging heat treatment has a martensite fraction of 85% by volume or more.

8. A heat-treated stainless steel shaping material, The alloy contains, in mass%, C: 0.070% or less, Si: 0.30% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, Cr: 14.0% or more and 17.5% or less, Ni: 3.0% or more and 6.0% or less, V: 0.01% or more and 0.10% or less, N: 0.100% or less, Mo: 0.03% or more and 0.10% or less, Cu: 2.5% or more and 5.0% or less, and Nb: 0.15% or more and 0.45% or less, with the balance being inevitable impurities and Fe, and has a composition that satisfies the following formula (1): Nieq≧0.923Creq - 8.537...(1) where Nieq and Creq are calculated using equations (2) and (3). Nieq=(mass%Ni)+30(mass%C)+0.5(mass%Mn)+0.3(mass%Cu)+25(mass%N)...(2) Creq = (mass % Cr) + 2 (mass % Si) + 1.5 (mass % Mo) + 5 (mass % V) + 1.75 (mass % Nb) + 1.5 (mass % Ti) + 5.5 (mass % Al)... (3) 0.2% yield strength (0.2% Y.S.; MPa) at room temperature in accordance with JIS Z 2241:2022 and absorbed energy E (J / cm) in a Charpy impact test at 20°C in accordance with JIS Z2242:2022 ２ )but, A stainless steel forming material that satisfies the following formula (5) in the range of 500≦0.2% Y.S.≦1200 MPa: E≧−0.167 (0.2% Y.S.)+260…(5).

9. The stainless steel shaped material according to claim 8, wherein the 0.2% yield strength (0.2% Y.S.; MPa) is in the range of 600 MPa or more and 1150 MPa or less.

10. The 0.2% yield strength at room temperature in accordance with JIS Z 2241:2022 is 700 MPa or more, and the absorbed energy in a Charpy impact test at 20°C in accordance with JIS Z2242:2022 is 150 J / cm ２ The stainless steel shaped material according to claim 8, wherein the stainless steel shaped material is a shaped material having the above structure.

11. The stainless steel shaped material according to any one of claims 2 to 5 and 8 to 10, which is a metal additive manufacturing material.

12. In mass%, C: 0.070% or less, Si: 0.30% or less, Mn: 1.0% or less, P: 0.040% or less, S: 0.030% or less, Cr: 14.0% or more and 17.5% or less, Ni: 3.0% or more and 6.0%. Below, V: 0.01% or more and 0.10% or less, N: 0.100% or less, Mo: 0.03% or more and 0.10% or less, Cu: 2.5% or more and 5.0% or less, Nb: 0.15% or more and 0.45% or less, and the remainder is A shaping material is made of inevitable impurities and Fe and has a composition that satisfies the following formula (1), and is used to shaping a martensite structure with an average crystal grain size of less than 10 μm. The shaping material is then subjected to solution heat treatment and aging treatment to obtain a martensite structure with an average crystal grain size of less than 15 μm and a martensite volume fraction of 85% or more, an oxide area fraction of less than 0.2%, and an average diameter of 80 μm. The 0.2% proof stress (Y.S.; MPa) at room temperature in accordance with JIS Z 2241:2022 and absorbed energy E (J / cm) in a Charpy impact test at 20°C in accordance with JIS Z2242:2022 are obtained. ２ )but, 500≦0.2% Y.S.≦1200 MPa, satisfying the following formula (5): Manufacturing method for stainless steel molding material Nieq≧0.923Creq - 8.537...(1) where Nieq and Creq are calculated using equations (2) and (3). Nieq=(mass%Ni)+30(mass%C)+0.5(mass%Mn)+0.3(mass%Cu)+25(mass%N...(2) Creq = (mass % Cr) + 2 (mass % Si) + 1.5 (mass % Mo) + 5 (mass % V) + 1.75 (mass % Nb) + 1.5 (mass % Ti) + 5.5 (mass % Al)... (3) E≧−0.167 (0.2% Y.S.)+260…(5).

13. the solution treatment is performed under conditions of holding the steel sheet at a temperature of 950°C or higher and 1150°C or lower for 0.5 hours or higher and 10 hours or lower, and then cooling the steel sheet to room temperature at a rate of 90°C / h or higher; 13. The method for producing a stainless steel shaped material according to claim 12, wherein the aging treatment is performed under conditions such that the tempering parameter P after the solution heat treatment is 17,600 or more and 19,500 or less. where P is calculated using formula (4), T is the temperature (K), and t is the heat treatment time (h). P=T(log(t)+20)...(4).

14. The method for manufacturing a stainless steel shaped material according to claim 12 or 13, wherein the shaping is metal additive manufacturing.

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