WO2023113206A1 - Austenitic stainless steel and manufacturing method therefor - Google Patents

Austenitic stainless steel and manufacturing method therefor Download PDF

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Publication number
WO2023113206A1
WO2023113206A1 PCT/KR2022/016305 KR2022016305W WO2023113206A1 WO 2023113206 A1 WO2023113206 A1 WO 2023113206A1 KR 2022016305 W KR2022016305 W KR 2022016305W WO 2023113206 A1 WO2023113206 A1 WO 2023113206A1
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stainless steel
austenitic stainless
asp
equation
value
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PCT/KR2022/016305
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French (fr)
Korean (ko)
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송석원
박미남
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주식회사 포스코
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0273—Final recrystallisation annealing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite

Definitions

  • the present invention relates to an austenitic stainless steel and a method for manufacturing the same, and specifically, austenitic stainless steel capable of securing high strength and ductility at the same time even when low temperature annealing is performed, and having excellent cost competitiveness and corrosion resistance, and manufacturing thereof It's about how.
  • Stainless steel which has excellent corrosion resistance, does not require additional facility investment to improve corrosion resistance, so it is suitable for mass production of small items, which is a recent market trend, as well as transportation and construction parts.
  • austenitic stainless steel since its formability and elongation are excellent, it is easy to make complex shapes to meet various customer needs, and has the advantage of beautiful appearance.
  • the yield strength of frequently used austenitic stainless steel is 200 to 350 MPa, which is lower than that of carbon steel, limiting its application to structures.
  • an additional temper rolling process is performed after final annealing, but has a problem of a rapid decrease in elongation and formability of the material together with a cost increase problem.
  • general stainless steel contains expensive alloy components, there is a problem in that cost competitiveness is inferior.
  • Ni which is included in austenitic stainless steel, has a problem in terms of price competitiveness due to extreme fluctuations in material prices, not only supply and demand of raw materials are unstable, and it is difficult to secure stability of supply prices and the material itself is high.
  • Korean Patent Publication No. 10-2016-0138277 relates to an austenitic stainless steel and a manufacturing method thereof, C: 0.10% or less, Si: 1.0% or less, Mn: 2.1 to 6.0%, P: 0.045 % or less, S: 0.1% or less, Ni: 8.0 to 16.0%, Cr: 15.0 to 30.0%, Mo: 1.0 to 5.0%, N: 0.05 to 0.45%, Nb: 0 to 0.50%, and V: 0 to 0.50 %, the remainder being Fe and impurities, having a chemical composition satisfying the specific formula (1), having a grain size number of less than 8.0, and having a tensile strength of 690 MPa or more. , there is a problem that a large amount of nickel content is required.
  • the austenite phase is generally transformed into the martensite phase through cold rolling, and ultra-fine grains are implemented through low-temperature annealing in a subsequent step.
  • the ultra-fine grain is implemented, it is not easy to express a material having excellent yield strength and elongation at the same time.
  • the contents of Ni, Cr, Mn, etc. are different within the range where cost competitiveness can be secured, and the amount of martensitic phase transformation by cold working is different according to the ASP (Austenitic Stability Parameter) value, and TRIP (Transformation Induced Plasticity ) because the elongation changes according to the transformation behavior.
  • Patent Document 1 Republic of Korea Patent Publication No. 10-2016-0138277 (published date: 2016.12.02)
  • Embodiments of the present invention are intended to provide an austenitic stainless steel that can be used as an industrial material because of its excellent cost competitiveness and high corrosion resistance while securing excellent yield strength and elongation.
  • an embodiment of the present invention in weight percent, carbon (C): 0.005 ⁇ 0.060%, silicon (Si): 0.1 ⁇ 1.5%, manganese (Mn): 5.0 ⁇ 10.0% , Nickel (Ni): more than 0% and less than 3%, chromium (Cr): 14.0 to 18.0%, copper (Cu): more than 0% and less than 2.0%, nitrogen (N): 0.01 to 0.25%, balance of iron (Fe ) and unavoidable impurities, and satisfies that the ⁇ value defined by the following formula (1) is 10,000 or more, and the ⁇ value defined by the following formula (2) is 100 or more, to provide an austenitic stainless steel .
  • Equation (2-1): ASP 551-462 ([C] + [N]) -9.2 [Si] -8.1 [Mn] -13.7 [Cr] -29 ([Ni] + [Cu])
  • [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
  • the average grain size (d) of the thickness center is 5.0 ⁇ m or less.
  • Equation (2) may satisfy the range of 15 to 70.
  • the austenitic stainless steel may have a pitting potential value of 100 mV or more.
  • the austenitic stainless steel may have a yield strength of 540.0 MPa or more and an elongation of 30.0% or more.
  • [Ni], [Cr], [Mn], [N] means the content (% by weight) of each element
  • YS means the yield stress (MPa)
  • EL means elongation (%)
  • ASP Austenitic Stability Parameter
  • d means the average grain size ( ⁇ m) in the center of the thickness
  • Temp is the final annealing means temperature (° C.);
  • Equation (2-1): ASP 551-462 ([C] + [N]) -9.2 [Si] -8.1 [Mn] -13.7 [Cr] -29 ([Ni] + [Cu])
  • [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
  • the final annealing step may include being performed at a temperature range of 750 ⁇ 850 °C.
  • a step of primary annealing the hot-rolled steel sheet at 1000 to 1150 ° C. may be further included before the cold rolling.
  • the cold-rolled steel sheet may be rolled at a thickness reduction rate of 50% or more of the hot-rolled steel sheet in a room temperature temperature range.
  • the austenitic stainless steel may satisfy the ASP value in the range of 15 to 70.
  • the final annealed steel sheet may have an average grain size (d) of 5.0 ⁇ m or less at the center of the thickness.
  • an austenitic stainless steel having excellent yield strength and elongation, and containing a minimum amount of Ni and having low raw material cost.
  • the present invention can provide an austenitic stainless steel with excellent cost competitiveness and excellent strength, ductility and corrosion resistance, and a method for manufacturing the same.
  • Figure 2 shows the average grain size of the thickness center of austenitic stainless steel according to Examples and Comparative Examples.
  • One embodiment of the present invention in terms of weight percent, carbon (C): 0.005-0.060%, silicon (Si): 0.1-1.5%, manganese (Mn): 5.0-10.0%, nickel (Ni): greater than 0% 3% or less, chromium (Cr): 14.0 ⁇ 18.0%, copper (Cu): more than 0% and less than 2.0%, nitrogen (N): 0.01 ⁇ 0.25%, including the remaining amount of iron (Fe) and unavoidable impurities, Provided is an austenitic stainless steel that satisfies that the value of ⁇ defined by Equation (1) is 10,000 or more, and that the value of ⁇ defined by Equation (2) is 100 or more.
  • ASP (Austenitic Stability Parameter) is a value calculated by the following formula (2-1),
  • d is the mean grain size ( ⁇ m) of the center of the thickness
  • Equation (2-1): ASP 551-462 ([C] + [N]) -9.2 [Si] -8.1 [Mn] -13.7 [Cr] -29 ([Ni] + [Cu])
  • [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
  • Ultra Fine Grain (UFG) material is characterized by excellent strength-elongation balance, fatigue resistance, etching processability, etc.
  • a manufacturing method thereof is provided. Furthermore, it is characterized by providing an austenitic stainless steel sheet having yield strength and elongation suitable for structural members such as automobile outer panels and building parts.
  • manganese and nitrogen are used to maintain excellent performance while reducing the use of expensive elements such as nickel in order to improve cost competitiveness for heat of austenitic stainless steel.
  • Austenitic stainless steel in weight%, carbon (C): 0.005 ⁇ 0.060%, silicon (Si): 0.1 ⁇ 1.5%, manganese (Mn): 5.0 ⁇ 10.0%, copper (Cu): more than 0% and less than 2.0%, nickel (Ni): more than 0% and less than 3%, chromium (Cr): 14.0 to 18.0%, nitrogen (N): 0.01 to 0.25%, the balance of iron (Fe) and It may contain unavoidable impurities.
  • Carbon is an element effective for stabilizing the austenitic phase, and may be added in an amount of 0.005% or more to secure the yield strength of austenitic stainless steel.
  • the content is excessive, it not only reduces cold workability due to the solid solution strengthening effect, but also induces grain boundary precipitation of Cr carbide during low temperature annealing, which may adversely affect ductility, toughness, and corrosion resistance. Therefore, the upper limit should be limited to 0.060%.
  • Silicon is an element effective in improving corrosion resistance while serving as a deoxidizer during the steelmaking process, and may be added in an amount of 0.01% or more.
  • Si is an element effective in stabilizing the ferrite phase, and when added excessively, it promotes the formation of delta ( ⁇ ) ferrite in the casting material, which not only deteriorates hot workability, but also adversely affects the ductility and impact characteristics of the material. Therefore, the upper limit is set to 1.5%. can be limited
  • Manganese is an austenite phase stabilizing element added instead of nickel (Ni) in the present invention, and may be added in an amount of 5.0% or more to improve austenite stability.
  • the content is excessive, the ductility, toughness and corrosion resistance of the austenitic stainless steel may be reduced by excessive formation of S-based inclusions (MnS), and Mn fumes are generated during the steelmaking process, causing manufacturing risks. can be limited to 10.0%.
  • Nickel is a strong austenite phase stabilizing element and is essential to secure good hot workability and cold workability.
  • Ni is an expensive element, when a large amount is added, raw material cost increases. Accordingly, the upper limit may be limited to 3.0% in consideration of both cost and efficiency of steel.
  • chromium is a ferrite stabilizing element, it is effective in inhibiting martensite phase formation and can be added in an amount of 14.0% or more as a basic element for securing corrosion resistance required for stainless steel.
  • the content is excessive, the manufacturing cost increases and a large amount of delta ( ⁇ ) ferrite is formed in the material, resulting in a decrease in hot workability and adverse effects on material properties, so the upper limit can be limited to 18.0%.
  • Copper is an austenite phase stabilizing element and is added instead of nickel (Ni) in the present invention.
  • Cu may be added as an element to improve corrosion resistance in a reducing environment.
  • the upper limit may be limited to 2.0% in consideration of cost-efficiency and material characteristics of steel.
  • Nitrogen is a strong austenite stabilizing element and is effective in improving corrosion resistance and yield strength of austenitic stainless steel, and can be added in an amount of 0.01% or more. However, if the content is excessive, the hardening of the material and the decrease in hot workability may occur due to the solid solution strengthening effect, so the upper limit can be limited to 0.25%.
  • the austenitic stainless steel according to an embodiment of the present invention may further include at least one of phosphorus (P) and sulfur (S) as an unavoidable impurity.
  • the content of phosphorus (P) is 0.035% or less.
  • Phosphorus (P) is an impurity unavoidably contained in steel, and since it is an element that causes intergranular corrosion or impairs hot workability, it is desirable to control the content thereof as low as possible.
  • the upper limit of the P content is managed to 0.035% or less.
  • the content of sulfur (S) is 0.01% or less.
  • Sulfur (S) is an impurity that is unavoidably contained in steel, and since it is an element that segregates at grain boundaries and is a major cause of impairing hot workability, it is desirable to control its content as low as possible.
  • the upper limit of the S content is managed to 0.01% or less.
  • the remaining component of the present invention is iron (Fe).
  • Fe iron
  • the austenitic stainless steel is characterized in that the ⁇ value defined by the following formula (1) satisfies 10,000 or more.
  • the ⁇ value is 10,000 or more, there is an advantage in that high strength and high ductility can be realized while having cost competitiveness.
  • the austenitic stainless steel is characterized in that the ⁇ value defined by the following formula (2) satisfies 100 or more.
  • the ⁇ value is 100 or more, ultra-fine grains are formed, so that high strength and high ductility can be simultaneously realized.
  • ASP Austenitic Stability Parameter
  • Equation (2-1): ASP 551-462 ([C] + [N]) -9.2 [Si] -8.1 [Mn] -13.7 [Cr] -29 ([Ni] + [Cu])
  • [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
  • the average grain size (d) of the thickness center is preferably ultra-fine grains of 5.0 ⁇ m or less, and the ASP value of Equation (2) preferably satisfies the range of 15 to 70.
  • the austenitic stainless steel according to an embodiment has corrosion resistance of 100 mV or more when pitting potential is measured with a 3.5% NaCl solution at 30°C. There are great advantages.
  • the austenitic stainless steel according to one embodiment has the advantage of having excellent strength with a yield strength of 540.0 MPa or more and excellent ductility with an elongation of 30.0% or more.
  • the final cold rolling is performed at room temperature with a total sheet thickness reduction rate of 50% or more without annealing, and the final annealing is performed at an annealing temperature in the range of 750 to 850 ° C.
  • Coils or materials produced in the casting process are subjected to annealing at an annealing temperature of 1000 to 1150 ° C, followed by final cold rolling with a total plate thickness reduction rate of 50% or more at room temperature, followed by final annealing at a temperature in the range of 750 to 850 ° C.
  • the pitting potential value is 100 mV satisfied with the ideal
  • a method for manufacturing an austenitic stainless steel according to an embodiment of the present invention includes providing a material; manufacturing a hot-rolled steel sheet by hot-rolling the material; manufacturing a cold-rolled steel sheet by cold-rolling the hot-rolled steel sheet; and final annealing the cold-rolled steel sheet, and may further include performing primary annealing before the cold rolling.
  • Cr chromium
  • Cu copper
  • N nitrogen
  • a material containing the remaining amount of iron (Fe) and unavoidable impurities (ingot or slab) can be provided.
  • composition of the material preferably satisfies the ASP value defined by the following formula (2-1) in the range of 15 to 70.
  • [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
  • the manufacturing method of austenitic stainless steel according to an embodiment of the present invention includes controlling the ⁇ value defined by the following formula (1) to be 10,000 or more.
  • the value of ⁇ is controlled to be 10,000 or more, there is an advantage in implementing high strength and high ductility while having cost competitiveness.
  • Ni, Cr, Mn means the content (% by weight) of each element
  • YS means yield stress (MPa)
  • EL means elongation (%).
  • the manufacturing method of austenitic stainless steel according to an embodiment of the present invention includes controlling the ⁇ value defined by the following formula (2) to be 100 or more.
  • the ⁇ value is controlled to be 100 or more, ultra-fine grains having an average grain size (d) of 5.0 ⁇ m or less in the center of the thickness are formed, so that high strength and high ductility can be simultaneously realized.
  • ASP Austenitic Stability Parameter
  • d means the average grain size ( ⁇ m) of the center of the thickness, and is preferably 5.0 ⁇ m or less.
  • cold rolling may be performed without annealing, or cold rolling may be performed after primary annealing.
  • the primary annealing may be performed at a temperature of 1000 to 1150 °C.
  • the cold rolling step may be performed such that the thickness reduction rate of the hot-rolled steel sheet is rolled at 50% or more in a room temperature temperature range.
  • the final annealing step may be performed in a temperature range of 750 to 850 ° C., and further, the final annealing temperature is preferably controlled so that the ⁇ value defined by the following formula (3) is 0 or more.
  • the ⁇ value is controlled to be 0 or more, the balance of components such as manganese, chromium, and nitrogen is excellent, and sufficient corrosion resistance can be secured even when low-temperature annealing is performed.
  • [Cr], [N], [Mn] means the content (wt%) of each element
  • Temp means the final annealing temperature (°C).
  • the ⁇ value is controlled to be 0 or more
  • the pitting potential is measured with a 3.5% NaCl solution at 30 ° C
  • the pitting potential value measured is 100 mV or more, resulting in excellent corrosion resistance. can be achieved.
  • Table 1 Some of the steel grades in Table 1 are Lab. Ingots were prepared by vacuum melting, and some of the slabs were manufactured through an electric furnace-casting process, and Examples 1 to 10 at the final annealing temperature (Temp; °C) as shown in Table 2 below and coils of Comparative Examples 1 to 24 were prepared. The average grain size (d) was measured at the center of the thickness of the prepared material, and the yield strength (YS; MPa) and elongation (EL; %) were measured on a JIS13B tensile test piece.
  • Temp final annealing temperature
  • EL elongation
  • Examples 1 to 10 have ASP values in the range of 15 to 70, and the average grain size (d) value of the center of the thickness of the material satisfies 5 ⁇ m or less. On the other hand, in Comparative Examples 1 to 9 and 12 to 24, it can be confirmed that the ASP value is outside the range of 10 to 70, or the average grain size (d) of the center of the thickness of the material is 5.1 ⁇ m or more.
  • Examples 1 to 10 It is a cost-saving austenitic stainless steel that has high strength and high ductility and excellent corrosion resistance. Examples 1 to 10 all have an ⁇ value of 10,000 or more, a ⁇ value of 100 or more, and a ⁇ value of 0 or more. , it satisfies that the nominal potential value is 100 mV or more.
  • Comparative Examples 1 to 6 are standard austenitic stainless steels that are commercially produced, and are inferior in cost competitiveness because they use steels that do not fall within the component range of the present invention. It is insufficient, and has a problem of not realizing high strength and high ductility with cost competitiveness.
  • Comparative Examples 7 to 8, 12, 14, and 16 to 21 have a problem in that high strength and high ductility with cost competitiveness cannot be realized because the ⁇ value is less than 10,000 in common and does not meet the ⁇ value condition.
  • Comparative Examples 7 to 9, 12 to 15, and 18 to 24 have a problem in that the average grain size (d) of the thickness center of the material does not satisfy 5 ⁇ m or less, and the ⁇ value is less than 100.
  • Figure 2 shows the grain size of Example 1 and Comparative Example 9. Comparative examples that do not satisfy 5 ⁇ m or less form coarse crystal grains as shown on the right side of FIG. 2 (Comparative Example 9), and do not realize ultra-fine grains as shown on the left side of FIG. Accordingly, there is a problem in that high strength and high ductility cannot be implemented at the same time.
  • Comparative Examples 10 to 11 have a problem in that the ⁇ value is less than 0. This is a result of an incorrect component balance consisting of a large amount of Mn and low Cr, N, etc., and it is difficult to secure sufficient corrosion resistance of the material as low-temperature annealing proceeds.
  • the austenitic stainless steel according to the present invention has excellent cost competitiveness and excellent strength, ductility and corrosion resistance, its industrial applicability is recognized.

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Abstract

The present invention relates to an austenitic stainless steel and a manufacturing method therefor and, specifically, to an austenitic stainless steel and a manufacturing method therefor, wherein the austenitic stainless steel can secure both excellent strength and ductility even after undergoing low-temperature annealing and have excellent competitiveness and corrosion resistance.

Description

오스테나이트계 스테인리스 강 및 그 제조방법Austenitic stainless steel and manufacturing method thereof
본 발명은 오스테나이트계 스테인리스 강 및 그 제조방법에 관한 것으로, 구체적으로, 저온소둔을 진행하여도 높은 강도 및 연성을 동시에 확보할 수 있고, 원가경쟁력과 내식성이 우수한 오스테나이트계 스테인리스 강 및 이의 제조 방법에 관한 것이다.The present invention relates to an austenitic stainless steel and a method for manufacturing the same, and specifically, austenitic stainless steel capable of securing high strength and ductility at the same time even when low temperature annealing is performed, and having excellent cost competitiveness and corrosion resistance, and manufacturing thereof It's about how.
내식성이 뛰어난 스테인리스 강(Stainless Steel)은 내식성을 향상시키기 위한 별도의 설비투자를 필요로 하지 않아 운송용 부품 및 건축용 부품은 물론이고 최근 시장의 트랜드인 소품종 대량생산에도 적합한 소재이다. 특히, 오스테나이트계 스테인리스 강의 경우 그 성형성과 연신율이 우수하기 때문에 고객의 다양한 요구에 맞춰 복잡한 형상을 만들기 용이하고, 외관이 미려하다는 장점이 있다.Stainless steel, which has excellent corrosion resistance, does not require additional facility investment to improve corrosion resistance, so it is suitable for mass production of small items, which is a recent market trend, as well as transportation and construction parts. In particular, in the case of austenitic stainless steel, since its formability and elongation are excellent, it is easy to make complex shapes to meet various customer needs, and has the advantage of beautiful appearance.
다만, 빈번하게 사용하는 오스테나이트계 스테인리스 강의 항복강도는 200~350MPa 수준으로서, 탄소강 대비 낮아 구조물 적용에 한계가 있는 것이 현 실정이다. 이러한 범용 300계 스테인리스 강에서 보다 높은 항복강도를 얻기 위해서는 최종소둔 이후 추가적인 조질압연 공정을 거치게 되는데, 비용상승 문제와 함께 소재의 연신율 및 성형성의 급격한 감소문제를 가진다. 또한, 일반적인 스테인리스 강은 고가의 합금성분을 포함하고 있어 원가 경쟁력이 열위한 문제가 있다. 특히, 오스테나이트계 스테인리스 강에 포함되는 Ni은 소재 가격의 극심한 변동에 의해 원료수급이 불안정할 뿐만 아니라 공급가의 안정성 확보가 어려움과 동시에 그 소재가 자체가 높아 가격경쟁력 측면에서 문제가 있다.However, the yield strength of frequently used austenitic stainless steel is 200 to 350 MPa, which is lower than that of carbon steel, limiting its application to structures. In order to obtain a higher yield strength in such general-purpose 300 series stainless steel, an additional temper rolling process is performed after final annealing, but has a problem of a rapid decrease in elongation and formability of the material together with a cost increase problem. In addition, since general stainless steel contains expensive alloy components, there is a problem in that cost competitiveness is inferior. In particular, Ni, which is included in austenitic stainless steel, has a problem in terms of price competitiveness due to extreme fluctuations in material prices, not only supply and demand of raw materials are unstable, and it is difficult to secure stability of supply prices and the material itself is high.
예를 들어, 대한민국 공개특허 제10-2016-0138277호는 오스테나이트계 스테인리스 강 및 그 제조 방법에 관한 것으로, C：0.10% 이하, Si：1.0% 이하, Mn：2.1~6.0%, P：0.045% 이하, S：0.1% 이하, Ni：8.0~16.0%, Cr：15.0~30.0%, Mo：1.0~5.0%, N：0.05~0.45%, Nb：0~0.50%, 및 V：0~0.50%를 함유하며, 잔부가 Fe 및 불순물로 이루어지고, 특정 식(1)을 만족하는 화학 조성을 가지며, 결정 입도 번호가 8.0 미만이며, 690MPa 이상의 인장 강도를 가지는 오스테나이트계 스테인리스 강에 대해 개시하고 있으나, 많은 양의 니켈 함량이 요구되는 문제가 있다.For example, Korean Patent Publication No. 10-2016-0138277 relates to an austenitic stainless steel and a manufacturing method thereof, C: 0.10% or less, Si: 1.0% or less, Mn: 2.1 to 6.0%, P: 0.045 % or less, S: 0.1% or less, Ni: 8.0 to 16.0%, Cr: 15.0 to 30.0%, Mo: 1.0 to 5.0%, N: 0.05 to 0.45%, Nb: 0 to 0.50%, and V: 0 to 0.50 %, the remainder being Fe and impurities, having a chemical composition satisfying the specific formula (1), having a grain size number of less than 8.0, and having a tensile strength of 690 MPa or more. , there is a problem that a large amount of nickel content is required.
한편, 오스테나이트계 스테인리스 강에서의 초세립 구현 기술은, 일반적으로 냉간압연을 통하여 오스테나이트 상을 마르텐사이트 상으로 변태를 시키고, 그 후 단계에서 저온소둔을 통하여 초세립을 구현하게 된다. 하지만, 초세립이 구현되었다고 하더라도 항복강도와 연신율이 동시에 우수한 소재를 발현하기는 쉽지 않다. 원가경쟁력이 확보 가능한 범위 내에서의 Ni, Cr, Mn 등의 함량이 다르며, ASP(Austenitic Stability Parameter) 값에 따라 냉간가공에 따른 마르텐사이트 상 변태량이 다르며, 또한 인장시험시의 TRIP(Transformation Induced Plasticity) 변태 거동에 따라 연신율이 변하게 되기 때문이다.On the other hand, in the technology for realizing ultra-fine grains in austenitic stainless steel, the austenite phase is generally transformed into the martensite phase through cold rolling, and ultra-fine grains are implemented through low-temperature annealing in a subsequent step. However, even if the ultra-fine grain is implemented, it is not easy to express a material having excellent yield strength and elongation at the same time. The contents of Ni, Cr, Mn, etc. are different within the range where cost competitiveness can be secured, and the amount of martensitic phase transformation by cold working is different according to the ASP (Austenitic Stability Parameter) value, and TRIP (Transformation Induced Plasticity ) because the elongation changes according to the transformation behavior.
따라서, Ni과 같은 고가의 합금원소 함량을 최소한으로 줄이면서도, 우수한 항복강도, 연신율, 및 내식성이 동시에 확보 가능한 소재와 이의 제조방법의 개발이 요구된다.Therefore, it is required to develop a material capable of securing excellent yield strength, elongation, and corrosion resistance at the same time while reducing the content of expensive alloy elements such as Ni to a minimum, and a manufacturing method thereof.
(선행기술문헌정보)(Prior art literature information)
특허문헌1: 대한민국 공개특허 제10-2016-0138277호(공개일: 2016.12.02)Patent Document 1: Republic of Korea Patent Publication No. 10-2016-0138277 (published date: 2016.12.02)
본 발명의 실시예들은 우수한 항복강도와 연신율을 확보하면서도 원가경쟁력이 우수하고 내식성이 높아 산업용 소재로 사용 가능한 오스테나이트계 스테인리스 강을 제공하고자 한다.Embodiments of the present invention are intended to provide an austenitic stainless steel that can be used as an industrial material because of its excellent cost competitiveness and high corrosion resistance while securing excellent yield strength and elongation.
구체적으로, 본 발명에 따른 초세립 제조기술을 통해 자동차외판용, 건축 부품용 등으로 사용 가능한 고강도-고연성 오스테나이트계 스테인리스 강판 및 이의 제조 방법을 제공하고자 한다.Specifically, it is intended to provide a high-strength-high-ductility austenitic stainless steel sheet and a method for manufacturing the same that can be used for exterior panels for automobiles and building parts through the ultra-fine manufacturing technology according to the present invention.
그러나, 본원이 해결하고자 하는 과제는 이상에서 언급한 과제로 제한되지 않으며, 언급되지 않은 또 다른 과제들은 아래의 기재로부터 통상의 기술자에게 명확하게 이해될 수 있을 것이다.However, the problem to be solved by the present application is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.
상기와 같은 목적을 달성하기 위해, 본 발명의 일 실시예는, 중량%로, 탄소(C): 0.005~0.060%, 실리콘(Si): 0.1~1.5%, 망간(Mn): 5.0~10.0%, 니켈(Ni): 0% 초과 3% 이하, 크롬(Cr): 14.0~18.0%, 구리(Cu): 0% 초과 2.0% 이하, 질소(N): 0.01~0.25%, 잔량의 철(Fe) 및 불가피한 불순물을 포함하고, 하기 식(1)로 정의되는 α 값이 10,000 이상인 것을 만족하고, 하기 식(2)로 정의되는 β 값이 100 이상인 것을 만족하는, 오스테나이트계 스테인리스 강을 제공한다.In order to achieve the above object, an embodiment of the present invention, in weight percent, carbon (C): 0.005 ~ 0.060%, silicon (Si): 0.1 ~ 1.5%, manganese (Mn): 5.0 ~ 10.0% , Nickel (Ni): more than 0% and less than 3%, chromium (Cr): 14.0 to 18.0%, copper (Cu): more than 0% and less than 2.0%, nitrogen (N): 0.01 to 0.25%, balance of iron (Fe ) and unavoidable impurities, and satisfies that the α value defined by the following formula (1) is 10,000 or more, and the β value defined by the following formula (2) is 100 or more, to provide an austenitic stainless steel .
식(1): α = YS×EL-200(8[Ni]+[Cr]+3[Mn])Equation (1): α = YS×EL-200 (8[Ni]+[Cr]+3[Mn])
식(2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000001
]Equation (2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000001
]
상기 식(1) 및 식(2)에서, [Ni], [Cr], [Mn]는 각 원소의 함량(중량%)을 의미하고, YS는 항복응력(MPa)을 의미하고, EL은 연신율(%)을 의미하고, ASP(Austenitic Stability Parameter)는 하기 식(2-1)로 계산되는 값이고, d는 두께 중심부의 평균 결정립 크기(㎛)를 의미하고,In the above formulas (1) and (2), [Ni], [Cr], [Mn] means the content (wt%) of each element, YS means yield stress (MPa), and EL means elongation (%), ASP (Austenitic Stability Parameter) is a value calculated by the following formula (2-1), d is the average grain size (μm) of the center of the thickness,
식(2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])Equation (2-1): ASP = 551-462 ([C] + [N]) -9.2 [Si] -8.1 [Mn] -13.7 [Cr] -29 ([Ni] + [Cu])
상기 식(2-1)에서, [C], [N], [Si], [Mn], [Cr], [Ni], [Cu]는 각 원소의 함량(중량%)을 의미한다.In the above formula (2-1), [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
또한, 상기 두께 중심부의 평균 결정립 크기(d)가 5.0 ㎛ 이하인 것을 포함할 수 있다.In addition, it may include that the average grain size (d) of the thickness center is 5.0 ㎛ or less.
또한, 상기 식(2)의 ASP 값은 15~70 범위를 만족하는 것일 수 있다.In addition, the ASP value of Equation (2) may satisfy the range of 15 to 70.
또한, 상기 오스테나이트계 스테인리스 강은 공식전위(pitting potential) 값이 100 mV 이상일 수 있다.In addition, the austenitic stainless steel may have a pitting potential value of 100 mV or more.
또한, 상기 오스테나이트계 스테인리스 강은 항복강도가 540.0 MPa 이상이고, 연신율이 30.0% 이상일 수 있다.In addition, the austenitic stainless steel may have a yield strength of 540.0 MPa or more and an elongation of 30.0% or more.
상기와 같은 목적을 달성하기 위해, 본 발명의 다른 실시예는, 중량%로, 탄소(C): 0.005~0.060%, 실리콘(Si): 0.1~1.5%, 망간(Mn): 5.0~10.0%, 니켈(Ni): 0% 초과 3% 이하, 크롬(Cr): 14.0~18.0%, 구리(Cu): 0% 초과 2.0% 이하, 질소(N): 0.01~0.25%, 잔량의 철(Fe) 및 불가피한 불순물을 포함하는 소재를 제공하는 단계; 상기 소재를 열간 압연하여 열연 강판을 제조하는 단계; 상기 열연 강판을 냉간 압연하여 냉연 강판을 제조하는 단계; 및 상기 냉연 강판을 최종 소둔하는 단계;를 포함하며, 상기 최종 소둔된 강판이 하기 식(1)로 정의되는 α 값이 10,000 이상인 것을 만족하고, 하기 식(2)로 정의되는 β 값이 100 이상인 것을 만족하도록 제어되고, 하기 식(3)로 정의되는 γ값이 0 이상인 것을 만족하는 것을 특징으로 하는, 오스테나이트계 스테인리스 강의 제조 방법을 제공한다.In order to achieve the above object, another embodiment of the present invention, by weight, carbon (C): 0.005 ~ 0.060%, silicon (Si): 0.1 ~ 1.5%, manganese (Mn): 5.0 ~ 10.0% , Nickel (Ni): more than 0% and less than 3%, chromium (Cr): 14.0 to 18.0%, copper (Cu): more than 0% and less than 2.0%, nitrogen (N): 0.01 to 0.25%, balance of iron (Fe ) and providing a material containing unavoidable impurities; manufacturing a hot-rolled steel sheet by hot-rolling the material; manufacturing a cold-rolled steel sheet by cold-rolling the hot-rolled steel sheet; and finally annealing the cold-rolled steel sheet, wherein the final annealed steel sheet satisfies that the α value defined by the following equation (1) is 10,000 or more, and the β value defined by the following equation (2) is 100 or more. is controlled to satisfy the above, and the γ value defined by the following formula (3) is 0 or more is provided.
식(1): α = YS×EL-200(8[Ni]+[Cr]+3[Mn])Equation (1): α = YS×EL-200 (8[Ni]+[Cr]+3[Mn])
식(2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000002
]Equation (2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000002
]
식(3): γ = [Cr]+16[N]-0.5[Mn]-[390/
Figure PCTKR2022016305-appb-img-000003
]Equation (3): γ = [Cr] + 16 [N] -0.5 [Mn] - [390 /
Figure PCTKR2022016305-appb-img-000003
]
상기 식(1) 내지 식(3)에서, [Ni], [Cr], [Mn], [N] 는 각 원소의 함량(중량%)을 의미하고, YS는 항복응력(MPa)을 의미하고, EL은 연신율(%)을 의미하고, ASP(Austenitic Stability Parameter)는 하기 식(2-1)로 계산되는 값이고, d는 두께 중심부의 평균 결정립 크기(㎛)를 의미하며, Temp는 최종 소둔 온도(℃)를 의미하고;In the above formulas (1) to (3), [Ni], [Cr], [Mn], [N] means the content (% by weight) of each element, YS means the yield stress (MPa), , EL means elongation (%), ASP (Austenitic Stability Parameter) is a value calculated by the following formula (2-1), d means the average grain size (㎛) in the center of the thickness, Temp is the final annealing means temperature (° C.);
식(2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])Equation (2-1): ASP = 551-462 ([C] + [N]) -9.2 [Si] -8.1 [Mn] -13.7 [Cr] -29 ([Ni] + [Cu])
상기 식(2-1)에서, [C], [N], [Si], [Mn], [Cr], [Ni], [Cu]는 각 원소의 함량(중량%)을 의미한다.In the above formula (2-1), [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
또한, 상기 최종 소둔 단계는 750~850℃의 온도 범위에서 수행되는 것을 포함할 수 있다.In addition, the final annealing step may include being performed at a temperature range of 750 ~ 850 ℃.
또한, 상기 냉간 압연 전, 상기 열연 강판을 1000 내지 1150℃로 1차 소둔하는 단계를 추가 포함할 수 있다.In addition, a step of primary annealing the hot-rolled steel sheet at 1000 to 1150 ° C. may be further included before the cold rolling.
또한, 상기 냉간 압연 단계에서, 상기 냉연 강판은 상온 온도 범위에서 상기 열연 강판의 두께 감소율이 50% 이상으로 압연될 수 있다.In addition, in the cold rolling step, the cold-rolled steel sheet may be rolled at a thickness reduction rate of 50% or more of the hot-rolled steel sheet in a room temperature temperature range.
또한, 상기 오스테나이트계 스테인리스 강은, 상기 ASP 값이 15~70 범위를 만족할 수 있다.In addition, the austenitic stainless steel may satisfy the ASP value in the range of 15 to 70.
또한, 최종 소둔된 강판은, 두께 중심부의 평균 결정립 크기(d)가 5.0 ㎛ 이하일 수 있다.In addition, the final annealed steel sheet may have an average grain size (d) of 5.0 μm or less at the center of the thickness.
본 발명의 실시예에 따르면, 항복강도 및 연신율이 우수하며, Ni이 최소로 포함되어 원료비가 저렴한 오스테나이트계 스테인리스 강을 제공할 수 있다.According to an embodiment of the present invention, it is possible to provide an austenitic stainless steel having excellent yield strength and elongation, and containing a minimum amount of Ni and having low raw material cost.
본 발명은 원가경쟁력이 우수하면서도, 강도, 연성 및 내식성이 우수한 초세립 특성의 오스테나이트계 스테인리스 강 및 그 제조 방법을 제공할 수 있다.The present invention can provide an austenitic stainless steel with excellent cost competitiveness and excellent strength, ductility and corrosion resistance, and a method for manufacturing the same.
도 1은, 식(1)로 계산되는 α값과 식(2)로 계산되는 β값에 따른 실시예 범위와 비교예 범위를 나타낸다.1 shows the example range and the comparative example range according to the α value calculated by equation (1) and the β value calculated by equation (2).
도 2는, 실시예 및 비교예에 따른 오스테나이트계 스테인리스 강의 두께 중심부의 평균 결정립 크기를 도시한 것이다.Figure 2 shows the average grain size of the thickness center of austenitic stainless steel according to Examples and Comparative Examples.
본 발명의 일 실시예는, 중량%로, 탄소(C): 0.005~0.060%, 실리콘(Si): 0.1~1.5%, 망간(Mn): 5.0~10.0%, 니켈(Ni): 0% 초과 3% 이하, 크롬(Cr): 14.0~18.0%, 구리(Cu): 0% 초과 2.0% 이하, 질소(N): 0.01~0.25%, 잔량의 철(Fe) 및 불가피한 불순물을 포함하고, 하기 식(1)로 정의되는 α 값이 10,000 이상인 것을 만족하고, 하기 식(2)로 정의되는 β 값이 100 이상인 것을 만족하는, 오스테나이트계 스테인리스 강을 제공한다.One embodiment of the present invention, in terms of weight percent, carbon (C): 0.005-0.060%, silicon (Si): 0.1-1.5%, manganese (Mn): 5.0-10.0%, nickel (Ni): greater than 0% 3% or less, chromium (Cr): 14.0 ~ 18.0%, copper (Cu): more than 0% and less than 2.0%, nitrogen (N): 0.01 ~ 0.25%, including the remaining amount of iron (Fe) and unavoidable impurities, Provided is an austenitic stainless steel that satisfies that the value of α defined by Equation (1) is 10,000 or more, and that the value of β defined by Equation (2) is 100 or more.
식(1): α = YS×EL-200(8[Ni]+[Cr]+3[Mn])Equation (1): α = YS×EL-200 (8[Ni]+[Cr]+3[Mn])
식(2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000004
]Equation (2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000004
]
상기 식(1) 및 식(2)에서, In the above formulas (1) and (2),
[Ni], [Cr], [Mn]는 각 원소의 함량(중량%)을 의미하고,[Ni], [Cr], and [Mn] mean the content (% by weight) of each element,
YS는 항복응력(MPa)을 의미하고, YS means yield stress (MPa),
EL은 연신율(%)을 의미하고, EL means elongation (%),
ASP(Austenitic Stability Parameter)는 하기 식(2-1)로 계산되는 값이고,ASP (Austenitic Stability Parameter) is a value calculated by the following formula (2-1),
d는 두께 중심부의 평균 결정립 크기(㎛)를 의미한다;d is the mean grain size (μm) of the center of the thickness;
식(2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])Equation (2-1): ASP = 551-462 ([C] + [N]) -9.2 [Si] -8.1 [Mn] -13.7 [Cr] -29 ([Ni] + [Cu])
상기 식(2-1)에서, [C], [N], [Si], [Mn], [Cr], [Ni], [Cu]는 각 원소의 함량(중량%)을 의미한다.In the above formula (2-1), [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
본 명세서에서 사용되는 용어는 본 발명을 설명하기 위한 것이고, 본 발명을 한정하는 것을 의도하지 않는다. 또한, 본 명세서에서 사용되는 단수 형태들은 관련 정의가 이와 명백히 반대되는 의미를 나타내지 않는 한 복수 형태들도 포함한다. The terms used herein are intended to describe the present invention and are not intended to limit the present invention. Also, the singular forms used herein include the plural forms unless the related definition clearly dictates the contrary.
이하에서 특별한 언급이 없는 한 단위는 중량%이다. 또한, 어떤 부분이 어떤 구성요소를 “포함”한다고 할 때, 이는 특별히 반대되는 기재가 없는 한 다른 구성요소를 제외하는 것이 아니라 다른 구성요소를 더 포함할 수 있는 것을 의미한다.In the following, unless otherwise specified, units are % by weight. In addition, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.
달리 정의하지 않는 한, 본 명세서에서 사용되는 기술 용어 및 과학 용어를 포함하는 모든 용어들은 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자가 일반적으로 이해하는 의미와 동일한 의미를 가진다. 사전에 정의된 용어들은 관련 기술문헌과 현재 개시된 내용에 부합하는 의미를 가지도록 해석된다.Unless otherwise defined, all terms including technical terms and scientific terms used in this specification have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. The terms defined in the dictionary are interpreted to have a meaning consistent with the related technical literature and the currently disclosed content.
또한, 본 명세서의 "약", "실질적으로" 등은 언급한 의미에 고유한 제조 및 물질 허용오차가 제시될 때 그 수치에서 또는 그 수치에 근접한 의미로 사용되고, 본 발명의 이해를 돕기 위해 정확하거나 절대적인 수치가 언급된 개시 내용을 비양심적인 침해자가 부당하게 이용하는 것을 방지하기 위해 사용된다.In addition, "about", "substantially", etc. in this specification are used at or in the sense of or close to the value when manufacturing and material tolerances inherent in the stated meaning are presented, and are accurate to aid in understanding the present invention. or absolute numbers are used to prevent unfair use by unscrupulous infringers of the stated disclosure.
초세립(UFG: Ultra Fine Grain) 소재는 우수한 강도-연신 밸런스, 내피로 특성, 에칭 가공성 등을 특징을 가지는 것으로, 본 발명에서는 고강도-고연성 구현이 가능한 초세립을 가지는 오스테나이트계 스테인리스 강 및 이의 제조방법을 제공한다. 나아가, 자동차외판용, 건축 부품용 등과 같은 구조용 부재에 적합한 항복강도와 연신율을 갖는 오스테나이트계 스테인리스 강판을 제공하는 것을 특징으로 한다.Ultra Fine Grain (UFG) material is characterized by excellent strength-elongation balance, fatigue resistance, etching processability, etc. A manufacturing method thereof is provided. Furthermore, it is characterized by providing an austenitic stainless steel sheet having yield strength and elongation suitable for structural members such as automobile outer panels and building parts.
또한, 본 발명에서는 오스테나이트계 스테인리스 강의 열위한 원가경쟁력을 개선하기 위하여 니켈 등의 고가의 원소 사용을 줄이면서 우수한 성능을 유지하기 위하여 망간 및 질소를 사용하였다.In addition, in the present invention, manganese and nitrogen are used to maintain excellent performance while reducing the use of expensive elements such as nickel in order to improve cost competitiveness for heat of austenitic stainless steel.
이하, 본 발명의 일 측면에 따른 오스테나이트계 스테인리스 강에 대해 상세히 설명한다.Hereinafter, an austenitic stainless steel according to an aspect of the present invention will be described in detail.
[오스테나이트계 스테인리스 강][Austenitic Stainless Steel]
본 발명의 일 실시예에 따른 오스테나이트계 스테인리스 강은, 중량%로, 탄소(C): 0.005~0.060%, 실리콘(Si): 0.1~1.5%, 망간(Mn): 5.0~10.0%, 구리(Cu): 0% 초과 2.0% 이하, 니켈(Ni): 0% 초과 3% 이하, 크롬(Cr): 14.0~18.0%, 질소(N): 0.01~0.25%, 잔량의 철(Fe) 및 불가피한 불순물을 포함할 수 있다.Austenitic stainless steel according to an embodiment of the present invention, in weight%, carbon (C): 0.005 ~ 0.060%, silicon (Si): 0.1 ~ 1.5%, manganese (Mn): 5.0 ~ 10.0%, copper (Cu): more than 0% and less than 2.0%, nickel (Ni): more than 0% and less than 3%, chromium (Cr): 14.0 to 18.0%, nitrogen (N): 0.01 to 0.25%, the balance of iron (Fe) and It may contain unavoidable impurities.
[성분범위][Ingredient range]
탄소(C): 0.005% 내지 0.060%Carbon (C): 0.005% to 0.060%
탄소는 오스테나이트상 안정화에 효과적인 원소로, 오스테나이트계 스테인리스 강의 항복강도를 확보하기 위해 0.005% 이상 첨가할 수 있다. 다만 그 함량이 과도할 경우, 고용강화 효과에 의해 냉간 가공성을 저하시킬 뿐만 아니라 저온 소둔시 Cr 탄화물의 입계 석출을 유도하여 연성, 인성, 내식성 등에 악영향을 미칠 수 있으므로 그 상한을 0.060%로 한정할 수 있다.Carbon is an element effective for stabilizing the austenitic phase, and may be added in an amount of 0.005% or more to secure the yield strength of austenitic stainless steel. However, if the content is excessive, it not only reduces cold workability due to the solid solution strengthening effect, but also induces grain boundary precipitation of Cr carbide during low temperature annealing, which may adversely affect ductility, toughness, and corrosion resistance. Therefore, the upper limit should be limited to 0.060%. can
실리콘(Si): 0.1% 내지 1.5%Silicon (Si): 0.1% to 1.5%
실리콘은 제강공정 중 탈산제의 역할을 함과 동시에 내식성을 향상시키는데 효과적인 원소로 0.01% 이상 첨가할 수 있다. 그러나 Si은 페라이트상 안정화에 효과적인 원소로써 과잉 첨가 시 주조 소재 내 델타(δ)페라이트 형성을 조장하여 열간 가공성을 저하시킬 뿐만 아니라 재료의 연성 및 충격특성에 악영향을 미칠 수 있으므로 그 상한을 1.5%로 한정할 수 있다.Silicon is an element effective in improving corrosion resistance while serving as a deoxidizer during the steelmaking process, and may be added in an amount of 0.01% or more. However, Si is an element effective in stabilizing the ferrite phase, and when added excessively, it promotes the formation of delta (δ) ferrite in the casting material, which not only deteriorates hot workability, but also adversely affects the ductility and impact characteristics of the material. Therefore, the upper limit is set to 1.5%. can be limited
망간(Mn): 5.0% 내지 10.0%Manganese (Mn): 5.0% to 10.0%
망간은 본 발명에서 니켈(Ni) 대신 첨가되는 오스테나이트상 안정화 원소로, 오스테나이트 안정도를 향상시키기 위해 5.0% 이상 첨가할 수 있다. 다만 그 함량이 과도할 경우, S계 개재물(MnS)을 과량 형성하여 오스테나이트계 스테인리스 강의 연성, 인성 및 내식성을 저하시킬 수 있으며, 제강 공정도중 Mn 흄을 발생시켜 제조상 위험성을 동반하기 때문에 그 상한을 10.0%로 한정할 수 있다. Manganese is an austenite phase stabilizing element added instead of nickel (Ni) in the present invention, and may be added in an amount of 5.0% or more to improve austenite stability. However, if the content is excessive, the ductility, toughness and corrosion resistance of the austenitic stainless steel may be reduced by excessive formation of S-based inclusions (MnS), and Mn fumes are generated during the steelmaking process, causing manufacturing risks. can be limited to 10.0%.
니켈(Ni):0% 초과 3.0% 이하 Nickel (Ni): More than 0% and 3.0% or less
니켈은 강력한 오스테나이트상 안정화 원소로써 양호한 열간 가공성 및 냉간 가공성을 확보하기 위해서는 필수적이다. 그러나 Ni은 고가의 원소임에 따라 다량의 첨가 시 원료비용의 상승을 초래한다. 이에, 강재의 비용 및 효율성을 모두 고려하여 그 상한을 3.0%로 한정할 수 있다.Nickel is a strong austenite phase stabilizing element and is essential to secure good hot workability and cold workability. However, since Ni is an expensive element, when a large amount is added, raw material cost increases. Accordingly, the upper limit may be limited to 3.0% in consideration of both cost and efficiency of steel.
크롬(Cr): 14.0% 내지 18.0%Chromium (Cr): 14.0% to 18.0%
크롬은 페라이트 안정화 원소이지만 마르텐사이트상 생성 억제에 있어서 효과적이며, 스테인리스 강에 요구되는 내식성을 확보하는 기본 원소로 14.0% 이상 첨가할 수 있다. 다만 그 함량이 과도할 경우, 제조비용이 상승하고, 소재 내 델타(δ)페라이트를 다량 형성하여 열간 가공성의 저하와 재질특성에 악영향을 초래함에 따라 그 상한을 18.0%로 한정할 수 있다.Although chromium is a ferrite stabilizing element, it is effective in inhibiting martensite phase formation and can be added in an amount of 14.0% or more as a basic element for securing corrosion resistance required for stainless steel. However, if the content is excessive, the manufacturing cost increases and a large amount of delta (δ) ferrite is formed in the material, resulting in a decrease in hot workability and adverse effects on material properties, so the upper limit can be limited to 18.0%.
구리(Cu): 0% 초과 2.0% 이하Copper (Cu): greater than 0% and less than or equal to 2.0%
구리는 오스테나이트상 안정화 원소로, 본 발명에서 니켈(Ni) 대신 첨가되는 원소이다. Cu는 환원 환경에서의 내식성을 향상시키는 원소로 첨가할 수 있다. 다만 그 함량이 과도할 경우, 소재비용의 상승뿐만 아니라 액상화 및 저온취성의 문제점이 있다. 이에 강재의 비용-효율성 및 재질특성을 고려하여 그 상한을 2.0%로 한정할 수 있다.Copper is an austenite phase stabilizing element and is added instead of nickel (Ni) in the present invention. Cu may be added as an element to improve corrosion resistance in a reducing environment. However, when the content is excessive, there is a problem of liquefaction and low temperature brittleness as well as an increase in material cost. Accordingly, the upper limit may be limited to 2.0% in consideration of cost-efficiency and material characteristics of steel.
질소(N): 0.01% 내지 0.25%Nitrogen (N): 0.01% to 0.25%
질소는 강력한 오스테나이트 안정화 원소로, 오스테나이트계 스테인리스 강의 내식성 및 항복강도 향상에 효과적인 원소로 0.01% 이상 첨가할 수 있다. 다만 그 함량이 과도할 경우, 고용강화 효과에 의해 소재의 경질화 및 열간가공성 저하를 발생시킬 수 있으므로 그 상한을 0.25%로 한정할 수 있다.Nitrogen is a strong austenite stabilizing element and is effective in improving corrosion resistance and yield strength of austenitic stainless steel, and can be added in an amount of 0.01% or more. However, if the content is excessive, the hardening of the material and the decrease in hot workability may occur due to the solid solution strengthening effect, so the upper limit can be limited to 0.25%.
그 외 성분other ingredients
또한, 본 발명의 일 실시예에 따른 오스테나이트계 스테인리스 강은, 불가피한 불순물로 인(P) 및 황(S) 중 1종 이상을 더 포함할 수 있다.In addition, the austenitic stainless steel according to an embodiment of the present invention may further include at least one of phosphorus (P) and sulfur (S) as an unavoidable impurity.
인(P)의 함량은 0.035% 이하이다. 인(P)은 강 중 불가피하게 함유되는 불순물로, 입계 부식을 일으키거나 열간 가공성을 저해하는 주요 원인이 되는 원소이므로, 그 함량을 가능한 낮게 제어하는 것이 바람직하다. 본 발명에서는 상기 P 함량의 상한을 0.035% 이하로 관리한다.The content of phosphorus (P) is 0.035% or less. Phosphorus (P) is an impurity unavoidably contained in steel, and since it is an element that causes intergranular corrosion or impairs hot workability, it is desirable to control the content thereof as low as possible. In the present invention, the upper limit of the P content is managed to 0.035% or less.
황(S)의 함량은 0.01% 이하이다. 황(S)은 강 중 불가피하게 함유되는 불순물로, 결정립계에 편석되어 열간 가공성을 저해하는 주요 원인이 되는 원소이므로, 그 함량을 가능한 낮게 제어하는 것이 바람직하다. 본 발명에서는 상기 S 함량의 상한을 0.01% 이하로 관리한다.The content of sulfur (S) is 0.01% or less. Sulfur (S) is an impurity that is unavoidably contained in steel, and since it is an element that segregates at grain boundaries and is a major cause of impairing hot workability, it is desirable to control its content as low as possible. In the present invention, the upper limit of the S content is managed to 0.01% or less.
본 발명의 나머지 성분은 철(Fe)이다. 다만, 통상의 제조과정에서는 원료 또는 주위 환경으로부터 의도되지 않는 불순물들이 불가피하게 혼입될 수 있으므로, 이를 배제할 수는 없다. 이들 불순물들은 통상의 제조과정의 기술자라면 누구라도 알 수 있는 것이기 때문에 그 모든 내용을 특별히 본 명세서에서 언급하지는 않는다.The remaining component of the present invention is iron (Fe). However, since unintended impurities from raw materials or the surrounding environment may inevitably be mixed in a normal manufacturing process, this cannot be excluded. Since these impurities are known to anyone skilled in the ordinary manufacturing process, not all of them are specifically mentioned in this specification.
[파라미터 및 물성][Parameters and physical properties]
또한, 상기 오스테나이트계 스테인리스 강은, 하기 식(1)로 정의되는 α 값이 10,000 이상인 것을 만족하는 것을 특징으로 한다. 상기 α 값이 10,000 이상인 경우 원가경쟁력을 갖추면서도 고강도 및 고연성을 구현할 수 있는 이점이 있다.In addition, the austenitic stainless steel is characterized in that the α value defined by the following formula (1) satisfies 10,000 or more. When the α value is 10,000 or more, there is an advantage in that high strength and high ductility can be realized while having cost competitiveness.
식(1): α = YS×EL-200(8[Ni]+[Cr]+3[Mn])Equation (1): α = YS×EL-200 (8[Ni]+[Cr]+3[Mn])
상기 식(1) 에서, [Ni], [Cr], [Mn]는 각 원소의 함량(중량%)을 의미하고, YS는 항복응력(MPa)을 의미하고, EL은 연신율(%)을 의미한다.In the above formula (1), [Ni], [Cr], [Mn] means the content (% by weight) of each element, YS means yield stress (MPa), EL means elongation (%) do.
또한, 상기 오스테나이트계 스테인리스 강은, 하기 식(2)로 정의되는 β 값이 100 이상인 것을 만족하는 것을 특징으로 한다. 상기 β 값이 100 이상인 경우, 초세립이 형성되어 고강도 및 고연성을 동시에 구현할 수 있다.In addition, the austenitic stainless steel is characterized in that the β value defined by the following formula (2) satisfies 100 or more. When the β value is 100 or more, ultra-fine grains are formed, so that high strength and high ductility can be simultaneously realized.
식(2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000005
]Equation (2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000005
]
상기 식(2) 에서, ASP(Austenitic Stability Parameter)는 하기 식(2-1)로 계산되는 값이고, d는 두께 중심부의 평균 결정립 크기(㎛)를 의미한다.In the above formula (2), ASP (Austenitic Stability Parameter) is a value calculated by the following formula (2-1), and d means the average grain size (㎛) of the thickness center.
식(2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])Equation (2-1): ASP = 551-462 ([C] + [N]) -9.2 [Si] -8.1 [Mn] -13.7 [Cr] -29 ([Ni] + [Cu])
상기 식(2-1)에서, [C], [N], [Si], [Mn], [Cr], [Ni], [Cu]는 각 원소의 함량(중량%)을 의미한다.In the above formula (2-1), [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
상기 두께 중심부의 평균 결정립 크기(d)는 5.0 ㎛ 이하의 초세립인 것이 바람직하고, 상기 식(2)의 ASP 값은 15~70 범위를 만족하는 것이 바람직하다. The average grain size (d) of the thickness center is preferably ultra-fine grains of 5.0 μm or less, and the ASP value of Equation (2) preferably satisfies the range of 15 to 70.
일 실시예에 따른 오스테나이트계 스테인리스 강은, 30℃에서 3.5% 농도의 NaCl 용액으로 공식 전위값(pitting potential)을 측정했을 때, 측정되는 공식전위(pitting potential) 값이 100 mV 이상으로 내식성이 우수한 이점이 있다.The austenitic stainless steel according to an embodiment has corrosion resistance of 100 mV or more when pitting potential is measured with a 3.5% NaCl solution at 30°C. There are great advantages.
일 실시예에 따른 오스테나이트계 스테인리스 강은 항복강도가 540.0 MPa 이상으로 강도가 우수하고, 연신율이 30.0% 이상으로 연성이 우수한 특성을 가지는 이점이 있다.The austenitic stainless steel according to one embodiment has the advantage of having excellent strength with a yield strength of 540.0 MPa or more and excellent ductility with an elongation of 30.0% or more.
본 발명의 일 실시예에 따른 연주공정에서 생산된 소재를 열간압연을 행한 후에 소둔을 하지 않고 상온에서 총판두께감소율이 50% 이상인 최종냉간압연을 행한 후에 소둔 온도 750~850℃범위에서 최종 소둔된 코일, 또는 연주공정에서 생산된 소재를 열간 압연된 코일을 소둔 온도 1000~1150℃에서 소둔을 행한 후에 상온에서 총판두께감소율이 50%이상인 최종냉간압연을 행한 후에 소둔온도 750~850℃ 범위에서 최종 소둔된 코일에 대하여, 소재의 두께 중심부의 평균 결정립 크기(d) 값이 5㎛ 이하이면서, 3.5% NaCl 용액(30℃)으로 공식 전위값(pitting potential)을 측정했을 때, 공식전위 값이 100mV 이상인 것을 만족한다.After hot rolling the material produced in the casting process according to an embodiment of the present invention, the final cold rolling is performed at room temperature with a total sheet thickness reduction rate of 50% or more without annealing, and the final annealing is performed at an annealing temperature in the range of 750 to 850 ° C. Coils or materials produced in the casting process are subjected to annealing at an annealing temperature of 1000 to 1150 ° C, followed by final cold rolling with a total plate thickness reduction rate of 50% or more at room temperature, followed by final annealing at a temperature in the range of 750 to 850 ° C. Regarding the annealed coil, when the average grain size (d) value of the center of the thickness of the material is 5 μm or less and the pitting potential value is measured with a 3.5% NaCl solution (30 ° C), the pitting potential value is 100 mV satisfied with the ideal
[오스테나이트계 스테인리스 강의 제조 방법][Method for manufacturing austenitic stainless steel]
따라서, 이하에서는 본 발명의 일 구현예에 의한 오스테나이트계 스테인리스 강의 제조방법에 대하여 설명한다.Therefore, hereinafter, a method for manufacturing austenitic stainless steel according to an embodiment of the present invention will be described.
본 발명의 일 실시예에 따른 오스테나이트계 스테인리스 강의 제조 방법은, 소재를 제공하는 단계; 상기 소재를 열간 압연하여 열연 강판을 제조하는 단계; 상기 열연 강판을 냉간 압연하여 냉연 강판을 제조하는 단계; 및 상기 냉연 강판을 최종 소둔하는 단계;를 포함하며, 상기 냉간 압연 전, 1차 소둔하는 단계를 추가 포함할 수 있다.A method for manufacturing an austenitic stainless steel according to an embodiment of the present invention includes providing a material; manufacturing a hot-rolled steel sheet by hot-rolling the material; manufacturing a cold-rolled steel sheet by cold-rolling the hot-rolled steel sheet; and final annealing the cold-rolled steel sheet, and may further include performing primary annealing before the cold rolling.
상기 소재 제공 단계에서는, 중량%로, 탄소(C): 0.005~0.060%, 실리콘(Si): 0.1~1.5%, 망간(Mn): 5.0~10.0%, 니켈(Ni): 0% 초과 3.0% 이하, 크롬(Cr): 14.0~18.0%, 구리(Cu): 0% 초과 2.0% 이하, 질소(N): 0.01~0.25%, 잔량의 철(Fe) 및 불가피한 불순물을 포함하는 소재(잉곳 또는 슬라브)를 제공할 수 있다.In the material providing step, by weight, carbon (C): 0.005 to 0.060%, silicon (Si): 0.1 to 1.5%, manganese (Mn): 5.0 to 10.0%, nickel (Ni): more than 0% 3.0% Hereinafter, chromium (Cr): 14.0 to 18.0%, copper (Cu): more than 0% and less than 2.0%, nitrogen (N): 0.01 to 0.25%, a material containing the remaining amount of iron (Fe) and unavoidable impurities (ingot or slab) can be provided.
상기 소재의 조성은, 하기 식(2-1)으로 정의되는 ASP 값이 15~70 범위를 만족하는 것이 바람직하다.The composition of the material preferably satisfies the ASP value defined by the following formula (2-1) in the range of 15 to 70.
식(2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])Formula (2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])
상기 식에서, [C], [N], [Si], [Mn], [Cr], [Ni], [Cu]는 각 원소의 함량(중량%)을 의미한다.In the above formula, [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
또한, 본 발명의 일 실시예에 따른 오스테나이트계 스테인리스 강의 제조방법은, 하기 식(1)로 정의되는 α 값이 10,000 이상이 되도록 제어하는 것을 포함한다. 상기 α 값이 10,000 이상으로 제어되면, 원가경쟁력을 갖추면서도 고강도 및 고연성을 구현할 수 있는 이점이 있다.In addition, the manufacturing method of austenitic stainless steel according to an embodiment of the present invention includes controlling the α value defined by the following formula (1) to be 10,000 or more. When the value of α is controlled to be 10,000 or more, there is an advantage in implementing high strength and high ductility while having cost competitiveness.
식(1): α = YS×EL-200(8[Ni]+[Cr]+3[Mn])Equation (1): α = YS×EL-200 (8[Ni]+[Cr]+3[Mn])
상기 식(1) 에서, Ni, Cr, Mn는 각 원소의 함량(중량%)을 의미하고, YS는 항복응력(MPa)을 의미하고, EL은 연신율(%)을 의미한다.In the above formula (1), Ni, Cr, Mn means the content (% by weight) of each element, YS means yield stress (MPa), EL means elongation (%).
또한, 본 발명의 일 실시예에 따른 오스테나이트계 스테인리스 강의 제조방법은, 하기 식(2)로 정의되는 β 값이 100 이상이 되도록 제어하는 것을 포함한다. 상기 β 값이 100 이상으로 제어되면, 두께 중심부의 평균 결정립 크기(d)는 5.0 ㎛ 이하인 초세립이 형성되어 고강도 및 고연성을 동시에 구현할 수 있다.In addition, the manufacturing method of austenitic stainless steel according to an embodiment of the present invention includes controlling the β value defined by the following formula (2) to be 100 or more. When the β value is controlled to be 100 or more, ultra-fine grains having an average grain size (d) of 5.0 μm or less in the center of the thickness are formed, so that high strength and high ductility can be simultaneously realized.
식(2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000006
]Equation (2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000006
]
상기 식(2) 에서, ASP(Austenitic Stability Parameter)는 상술한 식(2-1)로 계산되는 값이고, 15~70 범위를 만족하는 것이 바람직하다. In Equation (2), ASP (Austenitic Stability Parameter) is a value calculated by Equation (2-1) described above, and preferably satisfies the range of 15 to 70.
d는 두께 중심부의 평균 결정립 크기(㎛)를 의미하며, 5.0 ㎛ 이하인 것이 바람직하다.d means the average grain size (μm) of the center of the thickness, and is preferably 5.0 μm or less.
상기 열간 압연 단계 후, 소둔을 하지 않고 냉간 압연을 수행할 수도 있고, 1차 소둔 후 냉간 압연을 수행할 수도 있다. 1차 소둔을 수행하는 경우, 1차 소둔은 1000 내지 1150℃의 온도에서 수행될 수 있다.After the hot rolling step, cold rolling may be performed without annealing, or cold rolling may be performed after primary annealing. When performing the primary annealing, the primary annealing may be performed at a temperature of 1000 to 1150 ℃.
상기 냉간 압연 단계는, 상온 온도 범위에서 상기 열연 강판의 두께 감소율이 50% 이상으로 압연되도록 수행될 수 있다.The cold rolling step may be performed such that the thickness reduction rate of the hot-rolled steel sheet is rolled at 50% or more in a room temperature temperature range.
상기 최종 소둔하는 단계는, 750~850℃의 온도 범위에서 수행될 수 있고, 나아가, 최종 소둔 온도는 하기 식(3)로 정의되는 γ값이 0 이상이 되도록 제어하는 것이 바람직하다. γ값이 0 이상으로 제어되면, 망간, 크롬, 질소 등의 성분 밸런스가 우수하여 저온소둔을 진행하여도 충분한 내식성 확보가 가능하다.The final annealing step may be performed in a temperature range of 750 to 850 ° C., and further, the final annealing temperature is preferably controlled so that the γ value defined by the following formula (3) is 0 or more. When the γ value is controlled to be 0 or more, the balance of components such as manganese, chromium, and nitrogen is excellent, and sufficient corrosion resistance can be secured even when low-temperature annealing is performed.
식(3): γ = [Cr]+16[N]-0.5[Mn]-[390/
Figure PCTKR2022016305-appb-img-000007
]Equation (3): γ = [Cr] + 16 [N] -0.5 [Mn] - [390 /
Figure PCTKR2022016305-appb-img-000007
]
상기 식(3)에서, [Cr], [N], [Mn]은 각 원소의 함량(중량%)을 의미하며, Temp는 최종 소둔 온도(℃)를 의미한다.In the above formula (3), [Cr], [N], [Mn] means the content (wt%) of each element, and Temp means the final annealing temperature (℃).
구체적으로, γ값이 0 이상으로 제어되면, 30℃에서 3.5% 농도의 NaCl 용액으로 공식 전위값(pitting potential)을 측정했을 때, 측정되는 공식전위(pitting potential) 값이 100 mV 이상으로 우수한 내식성을 달성할 수 있다.Specifically, when the γ value is controlled to be 0 or more, when the pitting potential is measured with a 3.5% NaCl solution at 30 ° C, the pitting potential value measured is 100 mV or more, resulting in excellent corrosion resistance. can be achieved.
[실시예][Example]
이하, 실시예를 통하여 본 발명을 보다 상세하게 설명하고자 한다.Hereinafter, the present invention will be described in more detail through examples.
오스테나이트계 스테인리스 강의 실시예 및 비교예에서 사용된 강종의 합금성분 및 조성범위와 하기 식(2-1)로 계산되는 주요 성분 파라미터인 ASP(Austenite Stability Parameter)값을 하기 표 1에 정리하였다.The alloy components and composition ranges of the steel types used in Examples and Comparative Examples of austenitic stainless steels and ASP (Austenite Stability Parameter) values, which are major component parameters calculated by the following formula (2-1), are summarized in Table 1 below.
식(2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])Formula (2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])
분류classification 성분(중량%)Ingredients (% by weight) ASPASP
C C Si Si Mn Mn Ni Ni Cr Cr Cu Cu N N
강종 1steel grade 1 0.030 0.030 0.5 0.5 8.5 8.5 2.5 2.5 15.5 15.5 1.2 1.2 0.20 0.20 51.6451.64
강종 2steel grade 2 0.040 0.040 0.5 0.5 8.5 8.5 2.0 2.0 16.0 16.0 2.5 2.5 0.20 0.20 16.9716.97
강종 3steel grade 3 0.040 0.040 0.5 0.5 9.2 9.2 1.2 1.2 15.5 15.5 1.8 1.8 0.20 0.20 61.6561.65
강종 4steel grade 4 0.030 0.030 0.4 0.4 9.5 9.5 1.9 1.9 15.2 15.2 1.5 1.5 0.20 0.20 57.2757.27
강종 5steel grade 5 0.030 0.030 0.4 0.4 9.5 9.5 2.5 2.5 16.2 16.2 1.0 1.0 0.22 0.22 31.4331.43
강종 6steel grade 6 0.030 0.030 1.0 1.0 9.5 9.5 1.9 1.9 15.2 15.2 1.0 1.0 0.23 0.23 52.3952.39
강종 7steel grade 7 0.120 0.120 0.6 0.6 0.9 0.9 6.8 6.8 17.1 17.1 0.0 0.0 0.05 0.05 28.1828.18
강종 8steel grade 8 0.055 0.055 0.4 0.4 1.1 1.1 8.1 8.1 18.2 18.2 0.1 0.1 0.04 0.04 7.387.38
강종 9steel grade 9 0.030 0.030 1.0 1.0 8.8 8.8 2.5 2.5 16.2 16.2 0.5 0.5 0.20 0.20 55.3255.32
강종 10steel grade 10 0.030 0.030 0.4 0.4 10.0 10.0 3.5 3.5 16.5 16.5 1.0 1.0 0.23 0.23 -10.35-10.35
강종 11steel grade 11 0.030 0.030 1.5 1.5 10.0 10.0 1.8 1.8 15.8 15.8 1.9 1.9 0.23 0.23 12.3212.32
상기 표 1의 강종으로 일부는 Lab. 진공용해를 하여 잉곳(Ingot)을 제조하였고, 일부는 전기로-연주 공정을 거쳐 슬라브(Slab)를 제작하였고, 하기 표 2에 나타낸 바와 같은 최종 소둔 온도(Temp; ℃)로 실시예 1 내지 10 및 비교예 1 내지 24의 코일을 제조하였다.평균 결정립 크기(d)는 상기 제조된 소재의 두께 중심부에서 측정하였고, 항복강도(YS; MPa) 및 연신율(EL; %)은, JIS13B 인장시험편에 대하여 상온에서 크로스헤드(crosshead) 10 mm/min ~ 20 mm/min 범위에서 인장시험을 수행하여 측정하였고, 공식전위(pitting potential)는 3.5% NaCl 용액(30℃)으로 측정하였으며, 그 결과들을 하기 표 2에 정리하였다.Some of the steel grades in Table 1 are Lab. Ingots were prepared by vacuum melting, and some of the slabs were manufactured through an electric furnace-casting process, and Examples 1 to 10 at the final annealing temperature (Temp; ℃) as shown in Table 2 below and coils of Comparative Examples 1 to 24 were prepared. The average grain size (d) was measured at the center of the thickness of the prepared material, and the yield strength (YS; MPa) and elongation (EL; %) were measured on a JIS13B tensile test piece. was measured by performing a tensile test in the crosshead range of 10 mm/min to 20 mm/min at room temperature, and the pitting potential was measured with a 3.5% NaCl solution (30 ° C), and the results are as follows. summarized in Table 2.
또한, 상기 표 1의 조성 및 측정 값들을 토대로, 하기 식(1) 내지 식(3)으로 정의되는 α, β, γ 값들을 계산하여 하기 표 2에 정리하였고, 도 1은, α값과 β값에 따른 실시예 범위와 비교예 범위를 나타낸다.In addition, based on the composition and measured values of Table 1, the values of α, β, and γ defined by the following formulas (1) to (3) were calculated and summarized in Table 2 below, and FIG. 1 shows the values of α and β Example ranges and comparative example ranges according to the values are shown.
식(1): α = YS(MPa)×EL(%)-200(8[Ni]+[Cr]+3[Mn])Equation (1): α = YS (MPa) × EL (%) -200 (8 [Ni] + [Cr] + 3 [Mn])
식(2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000008
]Equation (2): β = ASP + [150/
Figure PCTKR2022016305-appb-img-000008
]
식(3): γ = [Cr]+16[N]-0.5[Mn]-[390/
Figure PCTKR2022016305-appb-img-000009
]Equation (3): γ = [Cr] + 16 [N] -0.5 [Mn] - [390 /
Figure PCTKR2022016305-appb-img-000009
]
구분division 강 종류river type Temp.
(℃)Temp.
(℃) 		d
(㎛)d
(μm) 		YS
(MPa)YS
(MPa) 		EL
(%)EL
(%) 		공식전위
(mV)official vanguard
(mV) 		αα ββ γγ
실시예1Example 1 강종 1steel grade 1 800800 2.5 2.5 636.4 636.4 37.9 37.9 110.7 110.7 11919.56 11919.56 146.51 146.51 0.66 0.66
실시예2Example 2 강종 1steel grade 1 850850 3.2 3.2 543.8 543.8 42.2 42.2 106.1 106.1 10748.36 10748.36 135.49 135.49 1.07 1.07
실시예3Example 3 강종 2steel grade 2 850850 2.6 2.6 653.3 653.3 36.1 36.1 142.2 142.2 12084.13 12084.13 110.00 110.00 1.57 1.57
실시예4Example 4 강종 3steel grade 3 800800 2.2 2.2 658.6 658.6 38.6 38.6 107.6 107.6 14881.96 14881.96 162.78 162.78 0.31 0.31
실시예5Example 5 강종 3steel grade 3 850850 2.7 2.7 584.2 584.2 41.0 41.0 112.5 112.5 13412.20 13412.20 152.94 152.94 0.72 0.72
실시예6Example 6 강종 4steel grade 4 850850 4.9 4.9 599.7 599.7 38.6 38.6 103.5 103.5 11368.42 11368.42 125.03 125.03 0.27 0.27
실시예7Example 7 강종 5steel grade 5 750750 3.5 3.5 760.0 760.0 30.8 30.8 115.5 115.5 10468.00 10468.00 111.61 111.61 0.73 0.73
실시예8Example 8 강종 5steel grade 5 800800 4.4 4.4 666.1 666.1 35.9 35.9 109.0 109.0 10972.99 10972.99 102.94 102.94 1.18 1.18
실시예9Example 9 강종 6steel grade 6 800800 3.5 3.5 710.5 710.5 34.5 34.5 116.9 116.9 12732.25 12732.25 132.57 132.57 0.34 0.34
실시예10Example 10 강종 6steel grade 6 850850 4.4 4.4 650.5 650.5 37.3 37.3 107.5 107.5 12483.65 12483.65 123.90 123.90 0.75 0.75
비교예1Comparative Example 1 강종 7steel grade 7 800800 2.7 2.7 620.7 620.7 21.7 21.7 262.7 262.7 -1370.81 -1370.81 119.47 119.47 3.66 3.66
비교예2Comparative Example 2 강종 7steel grade 7 850850 4.1 4.1 569.3 569.3 22.8 22.8 311.7 311.7 -1859.96 -1859.96 102.26 102.26 4.07 4.07
비교예3Comparative Example 3 강종 7steel grade 7 10501050 25.5 25.5 494.7 494.7 50.1 50.1 388.3 388.3 9944.47 9944.47 57.88 57.88 5.41 5.41
비교예4Comparative Example 4 강종 8steel grade 8 800800 5.1 5.1 594.9 594.9 35.2 35.2 288.4 288.4 3680.48 3680.48 73.80 73.80 4.50 4.50
비교예5Comparative Example 5 강종 8steel grade 8 850850 8.7 8.7 593.5 593.5 36.8 36.8 284.0 284.0 4580.80 4580.80 58.23 58.23 4.91 4.91
비교예6Comparative Example 6 강종 8steel grade 8 10501050 27.7 27.7 465.8 465.8 47.2 47.2 332.4 332.4 4725.76 4725.76 35.88 35.88 6.25 6.25
비교예7Comparative Example 7 강종 1steel grade 1 10501050 20.9 20.9 402.9 402.9 54.7 54.7 109.3 109.3 9838.63 9838.63 84.45 84.45 2.41 2.41
비교예8Comparative Example 8 강종 2steel grade 2 10501050 26.3 26.3 420.0 420.0 47.7 47.7 192.8 192.8 8534.00 8534.00 46.22 46.22 2.91 2.91
비교예9Comparative Example 9 강종 3steel grade 3 10501050 25.9 25.9 413.3 413.3 53.6 53.6 152.4 152.4 11612.88 11612.88 91.11 91.11 2.06 2.06
비교예10Comparative Example 10 강종 4steel grade 4 750750 3.6 3.6 762.9 762.9 29.4 29.4 6.3 6.3 10649.26 10649.26 136.33 136.33 -0.59 -0.59
비교예11Comparative Example 11 강종 4steel grade 4 800800 4.0 4.0 655.0 655.0 36.1 36.1 26.8 26.8 11865.50 11865.50 132.27 132.27 -0.14 -0.14
비교예12Comparative Example 12 강종 4steel grade 4 10501050 26.8 26.8 430.2 430.2 50.0 50.0 142.2 142.2 9730.00 9730.00 86.25 86.25 1.61 1.61
비교예13Comparative Example 13 강종 5steel grade 5 850850 5.5 5.5 618.1 618.1 37.9 37.9 127.4 127.4 10485.99 10485.99 95.39 95.39 1.59 1.59
비교예14Comparative Example 14 강종 5steel grade 5 10501050 19.3 19.3 453.0 453.0 46.3 46.3 113.8 113.8 8033.90 8033.90 65.57 65.57 2.93 2.93
비교예15Comparative Example 15 강종 6steel grade 6 10501050 22.8 22.8 457.8 457.8 50.1 50.1 132.2 132.2 11155.78 11155.78 83.80 83.80 2.09 2.09
비교예16Comparative Example 16 강종 9steel grade 9 800800 2.5 2.5 730.4 730.4 29.1 29.1 74.1 74.1 8734.64 8734.64 150.19 150.19 1.21 1.21
비교예17Comparative Example 17 강종 9steel grade 9 850850 3.8 3.8 689.4 689.4 30.1 30.1 145.9 145.9 8230.94 8230.94 132.27 132.27 1.62 1.62
비교예18Comparative Example 18 강종 9steel grade 9 10501050 19.5 19.5 494.3 494.3 42.6 42.6 169.0 169.0 8537.18 8537.18 89.29 89.29 2.96 2.96
비교예19Comparative Example 19 강종 10steel grade 10 800800 7.1 7.1 661.7 661.7 35.6 35.6 81.1 81.1 8656.52 8656.52 45.94 45.94 1.39 1.39
비교예20Comparative Example 20 강종 10steel grade 10 850850 9.5 9.5 612.5 612.5 37.2 37.2 171.9 171.9 7885.00 7885.00 38.32 38.32 1.80 1.80
비교예21Comparative Example 21 강종 10steel grade 10 10501050 17.3 17.3 449.2 449.2 46.6 46.6 196.3 196.3 6032.72 6032.72 25.71 25.71 3.14 3.14
비교예22Comparative Example 22 강종 11steel grade 11 800800 5.1 5.1 742.9 742.9 33.6 33.6 51.2 51.2 12921.44 12921.44 78.74 78.74 0.69 0.69
비교예23Comparative Example 23 강종 11steel grade 11 850850 6.9 6.9 686.1 686.1 36.5 36.5 54.3 54.3 13002.65 13002.65 69.42 69.42 1.10 1.10
비교예24Comparative Example 24 강종 11steel grade 11 10501050 19.0 19.0 482.1 482.1 48.8 48.8 60.7 60.7 11486.48 11486.48 46.73 46.73 2.44 2.44
표 1 및 2를 참조하면, 실시예 1~10은 ASP 값이 15 ~ 70 범위를 가지면서, 소재의 두께 중심부의 평균 결정립 크기(d)값이 5㎛ 이하를 만족한다. 반면, 비교예 1~9 및 12~24는 ASP 값이 10~70 범위 밖이거나, 소재의 두께 중심부의 평균 결정립 크기(d)가 5.1㎛ 이상을 가지는 것을 확인할 수 있다.실시예 1~10은 고강도-고연성 구현이 가능하면서 내식성이 우수한 특성을 보유한 원가절감형 오스테나이트계 스테인리스 강으로, 실시예 1~10은 모두 α값 10,000 이상이면서, β값이 100 이상이면서, γ값이 0 이상이면서, 공식전위 값이 100mV 이상인 것을 만족한다.Referring to Tables 1 and 2, Examples 1 to 10 have ASP values in the range of 15 to 70, and the average grain size (d) value of the center of the thickness of the material satisfies 5 μm or less. On the other hand, in Comparative Examples 1 to 9 and 12 to 24, it can be confirmed that the ASP value is outside the range of 10 to 70, or the average grain size (d) of the center of the thickness of the material is 5.1 μm or more. Examples 1 to 10 It is a cost-saving austenitic stainless steel that has high strength and high ductility and excellent corrosion resistance. Examples 1 to 10 all have an α value of 10,000 or more, a β value of 100 or more, and a γ value of 0 or more. , it satisfies that the nominal potential value is 100 mV or more.
비교예 1~6은 상용적으로 생산되는 규격 오스테나이트계 스테인리스 강으로, 본 발명의 성분범위에 들어가지 않는 강종을 사용하여 원가경쟁력이 열위하며, 공통적으로 α값이 10,000 미만으로 α값 조건에 미달하며, 원가경쟁력을 갖춘 고강도, 고연성을 구현하지 못하는 문제점을 가진다.Comparative Examples 1 to 6 are standard austenitic stainless steels that are commercially produced, and are inferior in cost competitiveness because they use steels that do not fall within the component range of the present invention. It is insufficient, and has a problem of not realizing high strength and high ductility with cost competitiveness.
비교예 7~8, 12, 14, 16~21는 공통적으로 α값이 10,000 미만으로 α값 조건에 미달하여 원가경쟁력을 갖춘 고강도, 고연성을 구현하지 못하는 문제점을 가진다.Comparative Examples 7 to 8, 12, 14, and 16 to 21 have a problem in that high strength and high ductility with cost competitiveness cannot be realized because the α value is less than 10,000 in common and does not meet the α value condition.
비교예 7~9, 12~15, 18~24는 소재의 두께 중심부의 평균 결정립 크기(d)가 5㎛ 이하를 만족하지 못할 뿐만 아니라, β값이 100 미만을 가지는 문제가 있다. 도 2는 실시예 1 및 비교예 9의 결정립 크기를 도시한 것이다. 5㎛ 이하를 만족하지 못하는 비교예들은 도 2의 우측(비교예 9)에 나타낸 바와 같은 조대한 결정립이 형성되어, 도 2의 좌측(실시예 1)에 나타낸 바와 같은 초세립을 구현하지 못하고, 이에 따라 고강도 및 고연성을 동시에 구현하지 못하는 문제점을 가진다.Comparative Examples 7 to 9, 12 to 15, and 18 to 24 have a problem in that the average grain size (d) of the thickness center of the material does not satisfy 5 μm or less, and the β value is less than 100. Figure 2 shows the grain size of Example 1 and Comparative Example 9. Comparative examples that do not satisfy 5 μm or less form coarse crystal grains as shown on the right side of FIG. 2 (Comparative Example 9), and do not realize ultra-fine grains as shown on the left side of FIG. Accordingly, there is a problem in that high strength and high ductility cannot be implemented at the same time.
비교예 10~11은 γ값이 0 미만을 가지는 문제가 있다. 이는 다량의 Mn 및 낮은 Cr, N 등으로 구성된 성분 밸런스가 잘못된 결과로서, 저온소둔을 진행함에 따라 소재의 충분한 내식성 확보가 어렵기 때문에 내식성이 우수한 고강도 및 고연성을 동시에 구현하지 못하는 문제점을 가진다.Comparative Examples 10 to 11 have a problem in that the γ value is less than 0. This is a result of an incorrect component balance consisting of a large amount of Mn and low Cr, N, etc., and it is difficult to secure sufficient corrosion resistance of the material as low-temperature annealing proceeds.
상술한 바에 있어서, 본 발명의 예시적인 실시예들을 설명하였지만, 본 발명은 이에 한정되지 않으며 해당 기술 분야에서 통상의 지식을 가진 자라면 다음에 기재하는 특허청구범위의 개념과 범위를 벗어나지 않는 범위 내에서 다양한 변경 및 변형이 가능함을 이해할 수 있을 것이다.In the foregoing, exemplary embodiments of the present invention have been described, but the present invention is not limited thereto, and those skilled in the art are within the scope not departing from the concept and scope of the claims described below. It will be appreciated that various changes and modifications are possible.
본 발명에 따른 오스테나이트계 스테인리스 강은 원가경쟁력이 우수하면서도 강도, 연성 및 내식성이 우수하므로 산업상 이용가능성이 인정된다.Since the austenitic stainless steel according to the present invention has excellent cost competitiveness and excellent strength, ductility and corrosion resistance, its industrial applicability is recognized.

Claims (11)

  1. 중량%로, 탄소(C): 0.005~0.060%, 실리콘(Si): 0.1~1.5%, 망간(Mn): 5.0~10.0%, 니켈(Ni): 0% 초과 3% 이하, 크롬(Cr): 14.0~18.0%, 구리(Cu): 0% 초과 2.0% 이하, 질소(N): 0.01~0.25%, 잔량의 철(Fe) 및 불가피한 불순물을 포함하고,In % by weight, carbon (C): 0.005 to 0.060%, silicon (Si): 0.1 to 1.5%, manganese (Mn): 5.0 to 10.0%, nickel (Ni): greater than 0% and less than or equal to 3%, chromium (Cr) : 14.0 ~ 18.0%, copper (Cu): more than 0% and less than 2.0%, nitrogen (N): 0.01 ~ 0.25%, including the remaining amount of iron (Fe) and unavoidable impurities,
    하기 식(1)로 정의되는 α 값이 10,000 이상인 것을 만족하고,It satisfies that the α value defined by the following formula (1) is 10,000 or more,
    하기 식(2)로 정의되는 β 값이 100 이상인 것을 만족하는, 오스테나이트계 스테인리스 강.An austenitic stainless steel that satisfies that the β value defined by the following formula (2) is 100 or more.
    식(1): α = YS×EL-200(8[Ni]+[Cr]+3[Mn])Equation (1): α = YS×EL-200 (8[Ni]+[Cr]+3[Mn])
    식(2): β = ASP + [150/
    Figure PCTKR2022016305-appb-img-000010
    ]    Equation (2): β = ASP + [150/
    Figure PCTKR2022016305-appb-img-000010
    ]
    상기 식(1) 및 식(2)에서, In the above formulas (1) and (2),
    [Ni], [Cr], [Mn]는 각 원소의 함량(중량%)을 의미하고,[Ni], [Cr], and [Mn] mean the content (% by weight) of each element,
    YS는 항복응력(MPa)을 의미하고, YS means yield stress (MPa),
    EL은 연신율(%)을 의미하고, EL means elongation (%),
    ASP(Austenitic Stability Parameter)는 하기 식(2-1)로 계산되는 값이고,ASP (Austenitic Stability Parameter) is a value calculated by the following formula (2-1),
    d는 두께 중심부의 평균 결정립 크기(㎛)를 의미한다;d is the mean grain size (μm) of the center of the thickness;
    식(2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])Equation (2-1): ASP = 551-462 ([C] + [N]) -9.2 [Si] -8.1 [Mn] -13.7 [Cr] -29 ([Ni] + [Cu])
    상기 식(2-1)에서, [C], [N], [Si], [Mn], [Cr], [Ni], [Cu]는 각 원소의 함량(중량%)을 의미한다.In the above formula (2-1), [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
  2. 청구항 1에 있어서,The method of claim 1,
    상기 두께 중심부의 평균 결정립 크기(d)가 5.0 ㎛ 이하인 것인, 오스테나이트계 스테인리스 강.The average grain size (d) of the thickness center is 5.0 μm or less, austenitic stainless steel.
  3. 청구항 1에 있어서,The method of claim 1,
    상기 식(2)의 ASP 값은 15~70 범위를 만족하는 것인, 오스테나이트계 스테인리스 강.The ASP value of Equation (2) satisfies the range of 15 to 70, austenitic stainless steel.
  4. 청구항 1에 있어서,The method of claim 1,
    상기 오스테나이트계 스테인리스 강은 공식전위(pitting potential) 값이 100 mV 이상인 것인, 오스테나이트계 스테인리스 강.The austenitic stainless steel has a pitting potential value of 100 mV or more, the austenitic stainless steel.
  5. 청구항 1에 있어서,The method of claim 1,
    상기 오스테나이트계 스테인리스 강은 항복강도가 540.0 MPa 이상이고, 연신율이 30.0% 이상인 것인, 오스테나이트계 스테인리스 강.The austenitic stainless steel has a yield strength of 540.0 MPa or more and an elongation of 30.0% or more.
  6. 중량%로, 탄소(C): 0.005~0.060%, 실리콘(Si): 0.1~1.5%, 망간(Mn): 5.0~10.0%, 니켈(Ni): 0% 초과 3.0% 이하, 크롬(Cr): 14.0~18.0%, 구리(Cu): 0% 초과 2.0% 이하, 질소(N): 0.01~0.25%, 잔량의 철(Fe) 및 불가피한 불순물을 포함하는 소재를 제공하는 단계;In % by weight, carbon (C): 0.005 to 0.060%, silicon (Si): 0.1 to 1.5%, manganese (Mn): 5.0 to 10.0%, nickel (Ni): more than 0% and less than 3.0%, chromium (Cr) : 14.0 to 18.0%, copper (Cu): more than 0% and less than 2.0%, nitrogen (N): 0.01 to 0.25%, providing a material containing the balance of iron (Fe) and unavoidable impurities;
    상기 소재를 열간 압연하여 열연 강판을 제조하는 단계;manufacturing a hot-rolled steel sheet by hot-rolling the material;
    상기 열연 강판을 냉간 압연하여 냉연 강판을 제조하는 단계; 및manufacturing a cold-rolled steel sheet by cold-rolling the hot-rolled steel sheet; and
    상기 냉연 강판을 최종 소둔하는 단계;를 포함하며,Including; final annealing the cold-rolled steel sheet,
    상기 최종 소둔된 강판이 하기 식(1)로 정의되는 α 값이 10,000 이상인 것을 만족하고, 하기 식(2)로 정의되는 β 값이 100 이상인 것을 만족하도록 제어되고,Controlled so that the final annealed steel sheet satisfies that the α value defined by the following formula (1) is 10,000 or more, and the β value defined by the following formula (2) is 100 or more,
    하기 식(3)로 정의되는 γ값이 0 이상인 것을 만족하는 것을 특징으로 하는, 오스테나이트계 스테인리스 강의 제조 방법.A method for producing an austenitic stainless steel, characterized in that the γ value defined by the following formula (3) is 0 or more.
    식(1): α = YS×EL-200(8[Ni]+[Cr]+3[Mn])Equation (1): α = YS×EL-200 (8[Ni]+[Cr]+3[Mn])
    식(2): β = ASP + [150/
    Figure PCTKR2022016305-appb-img-000011
    ]    Equation (2): β = ASP + [150/
    Figure PCTKR2022016305-appb-img-000011
    ]
    식(3): γ = [Cr]+16[N]-0.5[Mn]-[390/
    Figure PCTKR2022016305-appb-img-000012
    ]    Equation (3): γ = [Cr] + 16 [N] -0.5 [Mn] - [390 /
    Figure PCTKR2022016305-appb-img-000012
    ]
    상기 식(1) 내지 식(3)에서, In the above formulas (1) to (3),
    [Ni], [Cr], [Mn], [N] 는 각 원소의 함량(중량%)을 의미하고,[Ni], [Cr], [Mn], [N] mean the content (% by weight) of each element,
    YS는 항복응력(MPa)을 의미하고, YS means yield stress (MPa),
    EL은 연신율(%)을 의미하고, EL means elongation (%),
    ASP(Austenitic Stability Parameter)는 하기 식(2-1)로 계산되는 값이고,ASP (Austenitic Stability Parameter) is a value calculated by the following formula (2-1),
    d는 두께 중심부의 평균 결정립 크기(㎛)를 의미하며,d means the average grain size (μm) of the center of the thickness,
    Temp는 최종 소둔 온도(℃)를 의미하고;Temp means the final annealing temperature (° C.);
    식(2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])Formula (2-1): ASP = 551-462([C]+[N])-9.2[Si]-8.1[Mn]-13.7[Cr]-29([Ni]+[Cu])
    상기 식(2-1)에서, [C], [N], [Si], [Mn], [Cr], [Ni], [Cu]는 각 원소의 함량(중량%)을 의미한다.In the above formula (2-1), [C], [N], [Si], [Mn], [Cr], [Ni], and [Cu] mean the content (wt%) of each element.
  7. 청구항 6에 있어서,The method of claim 6,
    상기 최종 소둔 단계는 750~850℃의 온도 범위에서 수행되는 것을 포함하는, 오스테나이트계 스테인리스 강의 제조방법.The final annealing step is a method for producing austenitic stainless steel comprising being performed at a temperature range of 750 to 850 ° C.
  8. 청구항 6에 있어서,The method of claim 6,
    상기 냉간 압연 전, 상기 열연 강판을 1000 내지 1150℃로 1차 소둔하는 단계를 추가 포함하는, 오스테나이트계 스테인리스 강의 제조방법.Method for producing austenitic stainless steel, further comprising the step of primary annealing the hot-rolled steel sheet at 1000 to 1150 ° C. before the cold rolling.
  9. 청구항 6에 있어서,The method of claim 6,
    상기 냉간 압연 단계에서, 상기 냉연 강판은 상온 온도 범위에서 상기 열연 강판의 두께 감소율이 50% 이상으로 압연되는 것인, 오스테나이트계 스테인리스 강의 제조방법.In the cold rolling step, the cold-rolled steel sheet is rolled at a thickness reduction rate of 50% or more of the hot-rolled steel sheet in the room temperature temperature range, austenitic stainless steel manufacturing method.
  10. 청구항 6에 있어서,The method of claim 6,
    상기 오스테나이트계 스테인리스 강은, 상기 ASP 값이 15~70 범위를 만족하는 것인, 오스테나이트계 스테인리스 강의 제조방법.The method of manufacturing austenitic stainless steel, wherein the austenitic stainless steel satisfies the ASP value in the range of 15 to 70.
  11. 청구항 6에 있어서,The method of claim 6,
    상기 최종 소둔된 강판은, 두께 중심부의 평균 결정립 크기(d)가 5.0 ㎛ 이하인 것인, 오스테나이트계 스테인리스 강의 제조방법.The method of manufacturing an austenitic stainless steel, wherein the final annealed steel sheet has an average grain size (d) of 5.0 μm or less in the center of the thickness.
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JP2014001422A (en) * 2012-06-18 2014-01-09 Nippon Steel & Sumitomo Metal Austenitic stainless steel plate and manufacturing method for the same
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JP2014001422A (en) * 2012-06-18 2014-01-09 Nippon Steel & Sumitomo Metal Austenitic stainless steel plate and manufacturing method for the same
WO2014157146A1 (en) * 2013-03-26 2014-10-02 日新製鋼株式会社 Austenitic stainless steel sheet and method for manufacturing high-strength steel material using same
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