Austenitic stainless steel and method for manufacturing the same

Abstract

We provide ultra-fine grain manufacturing technology that can realize high strength and high ductility for 304 and 301 series austenitic stainless steel sheets as replacements for tempered materials (especially 301 1 / 4H) for automotive exterior panels, building parts, automotive parts, etc. [Solution] The present invention is an austenitic stainless steel containing, by weight, 0.005-0.03% C, 0.1-1% Si, 0.1-2% Mn, 0.01-0.4% Cu, 0.01-0.2% Mo, 6-9% Ni, 16-19% Cr, 0.01-0.2% N, with the remainder being Fe and unavoidable impurities, having an Austenitic Stability Parameter (ASP) value calculated from 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo of 30-60, a [100*N] / [Ni+Cu] value of 1.4 or more, an average crystal grain size of less than 5 μm, and a crystal grain size fraction (%) of crystal grains having a size of 5 μm or more of less than 10%.

Description

Technical Field

[0001] The present invention relates to austenitic stainless steel and a method for manufacturing the same, and more particularly, to ultrafine-grained 304 series and 301 series austenitic stainless steels capable of realizing high strength and high ductility and a method for manufacturing the same.

Background Art

[0002] In fact, the applicability of general-purpose 304 series and 301 series austenitic stainless steels is limited to applications requiring high-strength characteristics such as structural materials due to their low yield strength (200 - 350 MPa). In order to obtain a higher yield strength than such general-purpose 300 series stainless steels, it is a common method to go through a quenching and tempering rolling process, but this causes a cost increase problem. The required characteristics of the 1 / 4H quenched and tempered material of the 301 series require a yield strength of 500 MPa or more, a tensile strength of 850 MPa or more, and an elongation of 25% or more. Accordingly, the present invention presents a method for manufacturing ultrafine-grained 300 series stainless steel capable of simultaneously realizing high yield strength, tensile strength, and excellent elongation without a quenching and tempering rolling process.

[0003] Ultrafine-grained (UFG: Ultra Fine Grain) materials have characteristics such as excellent strength-elongation balance, fatigue resistance, and etching processability. In the case of Patent Document 1, a method for manufacturing 300 series stainless steel with small bending even after half-etching by stress relief (SR) heat treatment twice after quenching and tempering rolling a cold-rolled annealed material for a laser metal mask for photoetching is described. However, in the case of Patent Document 1, as a manufacturing technique for controlling etching properties and bending after etching, it does not include technical content for structural parts having a thickness of 0.4 - 2.0 mm.

[0004] Furthermore, Patent Document 2 describes a method for producing components for nuclear power plants with an average crystal grain size of 10 μm or less, which involves heat treatment at a temperature of 600-700°C for 48 hours or more. However, Patent Document 2 has the problem that implementing it in an actual production line would reduce productivity and increase manufacturing costs due to the long heat treatment time. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 0216 / 043125 [Patent Document 2] Japanese Patent Publication No. 2020-50940 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The objective of this invention is to provide an ultrafine grain manufacturing technology that enables high strength and high ductility in 304 series and 301 series austenitic stainless steel sheets for use as a substitute for tempered materials (especially 301 1 / 4H) for applications such as automobile body panels, building components, and automobile parts.

[0007] Specifically, in the case of structural components, materials with a thickness of 0.4 to 2.0 mm are often used. Therefore, this invention aims to solve technical problems by focusing on low-cost component design and low-cost manufacturing technology that provide high strength and high ductility within this thickness range. In general, the technology for realizing ultrafine grains in 300 series stainless steel involves transforming the austenite phase into the martensite phase through cold rolling, and then realizing the ultrafine grains through low-temperature annealing in the subsequent stage. However, even if ultrafine grains are realized, it is not easy to produce a material with excellent yield strength, tensile strength, and elongation simultaneously. The Ni and Cr content differs within the 304 and 301 standard ranges, the amount of transformation of the martensite phase due to cold working differs depending on the ASP (Austenitic Stability Parameter) value, and the TRIP (Transformation Induced Plasticity) transformation behavior during tensile testing also differs, resulting in a considerable variety of tensile curve characteristics. Therefore, the present invention aims to provide a manufacturing technology for ultrafine-grained 300 series that enables high strength and high ductility through control of the ASP (Austenitic Stability Parameter) value calculated as 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo, control of the [100*N] / [Ni+Cu] value, control of the cold reduction ratio after hot rolling and annealing pickling of the slab, control of the annealing temperature after cold rolling, and control of the size fraction of crystal grains with a size of 5 μm or more. [Means for solving the problem]

[0008] The austenitic stainless steel of the present invention contains, by weight %, C: 0.005~0.03%, Si: 0.1~1%, Mn: 0.1~2%, Cu: 0.01~0.4%, Mo: 0.01~0.2%, Ni: 6~9%, Cr: 16~19%, and N: 0.01~0.2%, with the remainder being Fe and unavoidable impurities. The ASP (Austenitic Stability Parameter) value calculated using 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo is 30~60, the [100*N] / [Ni+Cu] value is 1.4 or greater, the average grain size is less than 5 μm, and the grain size fraction (%) of grains with a grain size of 5 μm or more is less than 10%.

[0009] The present invention provides a method for producing austenitic stainless steel, in weight percent, comprising C: 0.005-0.03%, Si: 0.1-1%, Mn: 0.1-2%, Cu: 0.01-0.4%, Mo: 0.01-0.2%, Ni: 6-9%, Cr: 16-19%, N: 0.01-0.2%, with the remainder being Fe and unavoidable impurities. The ASP (Austenitic Stability) is calculated as 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo. The process includes the steps of: producing a slab by a continuous casting process of austenitic stainless steel having a parameter value of 30 to 60, a [100*N] / [Ni+Cu] value of 1.4 or more, an average grain size of less than 5 μm, and a grain size fraction (%) of grains with a grain size of 5 μm or more of less than 10%; hot rolling and annealing the slab, followed by cold rolling to a cold reduction ratio of 60% or more; and annealing at an annealing temperature in the range of 800 to 850°C. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a manufacturing technology for a 300 series ultrafine-grained product that can replace 301 series 1 / 4H tempered material having a thickness in the range of 0.4 to 2.0 mm, while satisfying the required characteristics (yield strength of 500 MPa or more, tensile strength of 850 MPa or more, elongation of 25% or more). [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows the results of analyzing the Transverse Direction (TD) plane at the center of the thickness of the final cold-rolled product in Example 1 using an Electron Backscatter Diffraction (EBSD) pattern analyzer. Crystal grains with a size of 5 μm or larger are shown in gray, and their fractions are indicated. [Figure 2] This figure shows the results of analyzing the TD plane at the center of the thickness of the final cold-rolled product in Example 3 using a backscattered electron diffraction pattern analyzer. The grains showing a size of 5 μm or larger are indicated in gray, and their fractions are shown. [Figure 3] This figure shows the results of analyzing the TD plane at the center of the thickness of the final cold-rolled product of Comparative Example 1 using a backscattered electron diffraction pattern analyzer. Crystal grains with a size of 5 μm or larger are shown in gray, and their fractions are indicated. [Figure 4] This figure shows the results of analyzing the TD plane at the center of the thickness of the final cold-rolled product of Comparative Example 2 using a backscattered electron diffraction pattern analyzer. The grains showing a grain size of 5 μm or larger are indicated in gray, and their fractions are shown. [Figure 5] This graph shows the stress-strain curve for Example 1. [Figure 6] This graph shows the stress-strain curve for Comparative Example 1. [Figure 7] This graph shows the stress-strain curve for Comparative Example 2. [Figure 8] This graph shows the stress-strain curve for Comparative Example 5. [Modes for carrying out the invention]

[0012] The austenitic stainless steel of the present invention contains, by weight %, C: 0.005~0.03%, Si: 0.1~1%, Mn: 0.1~2%, Cu: 0.01~0.4%, Mo: 0.01~0.2%, Ni: 6~9%, Cr: 16~19%, and N: 0.01~0.2%, with the remainder being Fe and unavoidable impurities. The ASP (Austenitic Stability Parameter) value calculated using 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo is 30~60, the [100*N] / [Ni+Cu] value is 1.4 or greater, the average grain size is less than 5 μm, and the grain size fraction (%) of grains with a grain size of 5 μm or more is less than 10%.

[0013] Preferred embodiments of the present invention will be described below. However, embodiments of the present invention may be modified into various different forms, and the technical concept of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present invention are provided to give a more complete explanation of the present invention to a person with average skill in the art. The terms used in this invention are for the sole purpose of referring to specific embodiments and are not intended to limit the invention. Furthermore, the singular form used herein also includes the plural form unless the phrase clearly indicates the opposite. The meaning of “including” as used in this specification is to embody a particular characteristic, domain, constant, stage, operation, element and / or component, and does not exclude the existence or addition of other particular characteristics, domains, constants, stages, operations, elements, components and / or groups. All terms used herein, including technical and scientific terms unless otherwise defined, have the same meaning as generally understood by a person of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted as having a meaning consistent with the relevant technical literature and the content currently disclosed, and are not interpreted in their ideal or highly formal sense unless otherwise defined.

[0014] (Austenitic stainless steel) The austenitic stainless steel of the present invention contains, by weight %, C: 0.005 to 0.03%, Si: 0.1 to 1%, Mn: 0.1 to 2%, Cu: 0.01 to 0.4, Mo: 0.01 to 0.2, Ni: 6 to 9%, Cr: 16 to 19%, N: 0.01 to 0.2%, with the balance being Fe and unavoidable impurities, and the ASP (Austenitic Stability Parameter) value calculated by 551 - 462(C + N) - 9.2Si - 8.1Mn - 13.7Cr - 29(Ni + Cu) - 18.5Mo is 30 to 60, the [100*N] / [Ni + Cu] value is 1.4 or more, the average grain size is less than 5 μm, and the grain size fraction (%) of grains with a grain size of 5 μm or more is less than 10%.

[0015] (Component content) The carbon (C) content is 0.005 to 0.03% by weight. C is an austenite phase stabilizing element. Considering this, in the present invention, C is added at 0.005 wt% or more. However, when the C content is excessive, there is a problem that chromium carbides are formed during low-temperature annealing, reducing the intergranular corrosion resistance. Therefore, in the present invention, the C content is limited to 0.03 wt% or less.

[0016] The silicon (Si) content is 0.1 to 1% by weight. Si is a component added as a deoxidizer during steelmaking. When performing a bright annealing process, it has the effect of forming Si oxides in the passive film and improving the corrosion resistance of the steel. Considering this, in the present invention, Si is added at 0.1 wt% or more. However, when the Si content is excessive, there is a problem of reducing ductility, so in the present invention, the Si content is limited to 1.0 wt% or less.

[0017] The manganese (Mn) content is 0.1 to 2.0% by weight. [[ID=第十九]]

[0018] Mn is an austenite phase stabilizing element. Considering this, in the present invention, Mn is added at 0.1 wt% or more. However, when the Mn content is excessive, there is a problem of reducing corrosion resistance, so in the present invention, the content of Mn is limited to 2.0 wt% or less.

[0019] The nickel (Ni) content is 6.0-9.0% by weight. Ni is an austenite phase stabilizing element and has the effect of softening steel. Taking this into consideration, Ni is added in an amount of 6.0% by weight or more in this invention. However, since excessive Ni content leads to increased costs, the Ni content in this invention is limited to 9.0% by weight or less.

[0020] The chromium (Cr) content is 16.0-19.0% by weight. Cr is the main element for improving the corrosion resistance of stainless steel. Considering this, in this invention, Cr is added at a concentration of 16.0% by weight or more. However, if the Cr content is excessive, the steel hardens, which can suppress the deformation organic martensitic transformation during cold rolling. Therefore, in this invention, the Cr content is limited to 19.0% by weight or less.

[0021] The nitrogen (N) content is 0.01 to 0.2% by weight. N is an austenite phase stabilizing element and improves the strength of steel. Considering this, N may be added in amounts of 0.01% or more. However, excessive N content can lead to hardening of the steel and a decrease in hot workability; therefore, in this invention, the N content is limited to 0.2% by weight or less.

[0022] The copper (Cu) content is 0.01 to 0.4% by weight. Cu is an austenite phase stabilizing element and may be added in amounts of 0.01% or more. However, if the Cu content is excessive, the corrosion resistance of the steel decreases and costs increase. Therefore, in this invention, the Cu content is limited to 0.4% by weight or less.

[0023] The molybdenum (Mo) content is 0.01-0.2% by weight. Mo may be added in amounts of 0.01% or more because it has the effect of improving corrosion resistance and processability. However, since excessive Mo content leads to increased costs, the Mo content in this invention is limited to 0.2% by weight or less.

[0024] The remaining component of this invention is iron (Fe). However, in the normal manufacturing process, unintended impurities may inevitably be introduced from the raw materials or the surrounding environment, and these cannot be eliminated. Since such impurities are known to any technician in the normal manufacturing process, not all of them are specifically mentioned herein.

[0025] In the present invention, the Austenitic Stability Parameter (ASP) is calculated using 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo, and satisfies the range of 30 to 60. If the ASP value falls outside the above range, excessive TRIP (Transformation Induced Plasticity) transformation of the material occurs during tensile testing (excessive work hardening occurs), and the elongation rate targeted in the present invention is not met.

[0026] In this invention, the [100*N] / [Ni+Cu] value is 1.4 or higher. If it is less than 1.4, the amount of dissolved nitrogen contributing to the yield strength is low, and the yield strength targeted by this invention is not met.

[0027] (microstructure) If the average grain size is less than 5 μm, and the percentage of grains with a grain size of 5 μm or more is less than 10%, and the material falls outside the aforementioned range, the yield strength and tensile strength targeted by this invention are not met.

[0028] (characteristic) Furthermore, the austenitic stainless steel of the present invention may have a tensile strength of 850 MPa or more.

[0029] Furthermore, the austenitic stainless steel of the present invention may have a yield strength of 500 MPa or more.

[0030] Furthermore, the austenitic stainless steel of the present invention may have an elongation ratio of 25% or more.

[0031] (Manufacturing method for austenitic stainless steel) Another method for producing austenitic stainless steel according to the present invention involves a stainless steel containing, by weight %, C: 0.005~0.03%, Si: 0.1~1%, Mn: 0.1~2%, Cu: 0.01~0.4%, Mo: 0.01~0.2%, Ni: 6~9%, Cr: 16~19%, N: 0.01~0.2%, with the remainder being Fe and unavoidable impurities, and calculated as ASP (Austenitic Stability) = 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo. The process includes the steps of: producing a slab by a continuous casting process of austenitic stainless steel having a parameter value of 30 to 60, a [100*N] / [Ni+Cu] value of 1.4 or more, an average grain size of less than 5 μm, and a grain size fraction (%) of grains with a grain size of 5 μm or more of less than 10%; hot rolling and annealing the slab, followed by cold rolling to a cold reduction ratio of 60% or more; and annealing at an annealing temperature in the range of 800 to 850°C.

[0032] If the cold rolling annealing temperature falls outside the range of the present invention, the average grain size is 5 μm or larger, and the fraction of grains 5 μm or larger is 10% or larger, thus failing to meet the yield strength and tensile strength targets of the present invention.

[0033] If the cold reduction ratio (%) is less than 60%, the average grain size is 5 μm or larger, and the fraction of grains 5 μm or larger is 10% or more, so the yield strength targeted by this invention is not met.

[0034] (Examples) Table 1 shows the carbon, silicon, manganese, nickel, chromium, copper, and nitrogen components of examples and comparative examples of austenitic stainless steel, along with the main component parameters: ASP (Astenite Stability Parameter) value, [100*N] / [Ni+Cu] value, cold rolling rate (%) value, and cold rolling annealing temperature (°C) [annealing time within 5 minutes] value.

[0035] This corresponds to a coil produced by hot-rolling and then annealing a slab produced through a continuous casting process according to one embodiment of the present invention, followed by cold-rolling at room temperature and then cold-rolling and annealing. Part of the steel was used to produce ingots by lab-vacuum melting, and part of the steel was used to produce slabs through an electric furnace-continuous casting process. Examples 1 to 6 all have an ASP (Austenitic Stability Parameter) value in the range of 30 to 60 calculated using 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo, a [100*N] / [Ni+Cu] value of 1.4 or more, a cold-rolling rate (%) value of 60% or more, and a cold-rolling and annealing temperature (°C) value in the range of 800 to 850. Comparative Examples 1-11 show cases where the ASP (Austenitic Stability Parameter) value falls outside the range of 30-60, or the [100*N] / [Ni+Cu] value is less than 1.4, or the cold rolling rate (%) value is less than 60%, or the cold rolling annealing temperature (°C) value falls outside the range of 800-850.

[0036] [Table 1]

[0037] Table 2 shows the average grain size, grain fraction (%) of grains larger than 5 μm, and yield strength, tensile strength, and elongation values ​​obtained by room temperature tensile testing for JIS13B tensile test specimens, as analyzed by electron backscatter diffraction (EBSD) pattern analysis of the TD (Transverse Direction) plane at the center of the thickness of the final cold-rolled product.

[0038] [Table 2]

[0039] Examples 1 to 6 were found to have the characteristics of having an average grain size of less than 5 μm and a grain fraction (%) of grains larger than 5 μm of less than 10%. Furthermore, the Austenitic Stability Parameter (ASP) value was in the range of 30 to 60, and the [100*N] / [Ni+Cu] value was 1.4 or higher, ultimately satisfying the required properties of 301-type 1 / 4H tempered material (yield strength of 500 MPa or higher, tensile strength of 850 MPa or higher, and elongation of 25% or higher).

[0040] Comparative Example 1 does not satisfy the yield strength and tensile strength targeted by the present invention because its cold rolling annealing temperature value falls outside the range of the present invention, its average grain size is 5 μm or larger, and the fraction of grains 5 μm or larger is 10% or larger. Comparative Examples 2, 3, and 4 have ASP (Austenitic Stability Parameter) values ​​outside the range of the present invention, and during tensile testing, the material does not undergo TRIP (Transformation Induced Plasticity) transformation (work hardening does not occur well), thus failing to satisfy the tensile strength targeted by the present invention.

[0041] Comparative Examples 5 and 6 have ASP (Austenitic Stability Parameter) values ​​outside the range of the present invention, resulting in excessive TRIP (Transformation Induced Plasticity) transformation of the material during tensile testing (excessive work hardening), and failing to meet the elongation ratio targeted by the present invention. Comparative Example 7 has a [100*N] / [Ni+Cu] value outside the range of the present invention, resulting in a low amount of dissolved nitrogen contributing to the yield strength, and failing to meet the yield strength targeted by the present invention. Comparative Examples 8 and 9 have ASP (Austenitic Stability Parameter) values ​​and [100*N] / [Ni+Cu] values ​​outside the range of the present invention, with an average grain size of 5 μm or more and a grain fraction of 5 μm or more of 10% or more, thus failing to meet the yield strength and tensile strength targeted by the present invention. Comparative Examples 10 and 11 do not satisfy the yield strength target of the present invention because their cold reduction ratio (%) values ​​fall outside the range of the present invention, their average grain size is 5 μm or larger, and their grain fraction of 5 μm or larger is 10% or larger.

[0042] As shown in Figure 1, analysis of the Transverse Direction (TD) plane at the center of the thickness of the final cold-rolled product in Example 1 using an Electron Backscatter Diffraction (EBSD) pattern analyzer revealed that the grain fraction with a grain size of 5 μm or larger was 0%.

[0043] As shown in Figure 2, analysis of the TD plane at the center of the thickness of the final cold-rolled product in Example 3 using a backscattered electron diffraction pattern analyzer revealed that the grain fraction with a grain size of 5 μm or larger was 7%.

[0044] As shown in Figure 3, analysis of the TD plane at the center of the thickness of the final cold-rolled product of Comparative Example 1 using a backscattered electron diffraction pattern analyzer revealed that the grain fraction with a grain size of 5 μm or larger was 85%.

[0045] As shown in Figure 4, analysis of the TD plane at the center of the thickness of the final cold-rolled product of Comparative Example 2 using a backscatter electron diffraction pattern analyzer revealed that the grain fraction with a grain size of 5 μm or larger was 14%.

[0046] Figures 5-8 are graphs showing the stress-strain curves of the examples and comparative examples. Figure 5 is the graph for Example 1, Figure 6 is the graph for Comparative Example 1, Figure 7 is the graph for Comparative Example 2, and Figure 8 is the graph for Comparative Example 5. Comparing Figures 5-8, it can be seen that the austenitic stainless steel according to one example of the present invention has a relatively small rate of stress change due to the degree of deformation, and therefore can simultaneously satisfy high strength and high elongation compared to the comparative examples.

[0047] Although exemplary embodiments of the present invention have been described above, the present invention is not limited thereto, and a person with ordinary skill in the art will understand that various modifications and variations are possible without departing from the concepts and scope of the claims described below. [Industrial applicability]

[0048] According to the present invention, it is possible to provide an ultrafine-grained stainless steel that can replace 301-series 1 / 4H tempered stainless steel having a thickness in the range of 0.4 to 2.0 mm, satisfying the required characteristics (yield strength of 500 MPa or more, tensile strength of 850 MPa or more, elongation of 25% or more), and thus having industrial applicability.

Claims

1. In weight percent, it contains C: 0.005-0.03%, Si: 0.1-1%, Mn: 0.1-2%, Cu: 0.01-0.4%, Mo: 0.01-0.2%, Ni: 6-9%, Cr: 16-19%, N: 0.01-0.2%, with the remainder being Fe and unavoidable impurities. The ASP (Austential Stability Parameter) value calculated using 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo is between 36.3 and 46.

3. The value of [100*N] / [Ni+Cu] is 1.4 or greater. An austenitic stainless steel material characterized by having an average grain size of less than 5 μm and a grain size fraction (%) of grains with a size of 5 μm or more of less than 10%.

2. The austenitic stainless steel material according to claim 1, characterized in that the austenitic stainless steel material has a tensile strength of 850 MPa or more.

3. The austenitic stainless steel material is characterized in that the austenitic stainless steel material has a yield strength of 500 MPa or more, as described in claim 1.

4. The austenitic stainless steel material according to claim 1, characterized in that the austenitic stainless steel material has an elongation rate of 25% or more.

5. In weight percent, it contains C: 0.005-0.03%, Si: 0.1-1%, Mn: 0.1-2%, Cu: 0.01-0.4%, Mo: 0.01-0.2%, Ni: 6-9%, Cr: 16-19%, N: 0.01-0.2%, with the remainder being Fe and unavoidable impurities. The ASP (Austential Stability Parameter) value calculated using 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo is between 36.3 and 46.

3. A step of manufacturing a slab of austenitic stainless steel material, characterized by having a [100*N] / [Ni+Cu] value of 1.4 or more, through a continuous casting process, The slab is subjected to hot rolling and annealing pickling, followed by cold rolling to a cold reduction ratio of 60% or more. This includes the step of annealing at an annealing temperature in the range of 800 to 850°C, A method for manufacturing an austenitic stainless steel, characterized in that the average grain size of the austenitic stainless steel after annealing at an annealing temperature in the range of 800 to 850°C is less than 5 μm, and the grain size fraction (%) of grains with a grain size of 5 μm or more is less than 10%.

6. The method for manufacturing an austenitic stainless steel material according to claim 5, characterized in that the austenitic stainless steel material has a tensile strength of 850 MPa or more.

7. The method for manufacturing an austenitic stainless steel material according to claim 5, characterized in that the austenitic stainless steel material has a yield strength of 500 MPa or more.

8. The method for manufacturing an austenitic stainless steel material according to claim 5, characterized in that the austenitic stainless steel material has an elongation rate of 25% or more.

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