WO2020085852A1 - Acier austénitique à haute teneur en manganèse ayant une haute limite d'élasticité et son procédé de fabrication - Google Patents

Acier austénitique à haute teneur en manganèse ayant une haute limite d'élasticité et son procédé de fabrication Download PDF

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WO2020085852A1
WO2020085852A1 PCT/KR2019/014175 KR2019014175W WO2020085852A1 WO 2020085852 A1 WO2020085852 A1 WO 2020085852A1 KR 2019014175 W KR2019014175 W KR 2019014175W WO 2020085852 A1 WO2020085852 A1 WO 2020085852A1
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yield strength
less
manganese steel
austenitic high
excellent yield
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PCT/KR2019/014175
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English (en)
Korean (ko)
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이운해
김보성
강상덕
석정훈
김우철
김용진
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주식회사 포스코
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Priority claimed from KR1020190118926A external-priority patent/KR102290780B1/ko
Application filed by 주식회사 포스코 filed Critical 주식회사 포스코
Priority to CN201980069181.4A priority Critical patent/CN112912530B/zh
Priority to EP19876536.4A priority patent/EP3872215A4/fr
Publication of WO2020085852A1 publication Critical patent/WO2020085852A1/fr

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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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • 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
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing 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
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium 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
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese

Definitions

  • the present invention relates to an austenitic high-manganese steel material and a method for manufacturing the same, and more particularly to an austenitic high-manganese steel material having excellent ductility and excellent yield strength and a method for manufacturing the same.
  • the austenitic high-manganese steel material is characterized by having high toughness by stabilizing austenite in an ambient or cryogenic environment by adjusting the contents of manganese (Mn) and carbon (C), which are elements that enhance the stability of austenite.
  • Patent Document 1 Republic of Korea Patent Publication No. 10-2015-0075324 (2015.07.03. Public)
  • an austenitic high-manganese steel material having excellent yield strength and a method of manufacturing the same can be provided.
  • the austenitic high-manganese steel material having excellent yield strength according to an aspect of the present invention is, by weight, C: 0.2 to 0.5%, Mn: 20 to 28%, Si: 0.05 to 0.5%, P: 0.03% or less, S: 0.005% or less, Al: 0.005 ⁇ 0.05%, including residual Fe and other unavoidable impurities, and containing 95% by area or more of austenite as a microstructure, but the grain boundary in the grains of the microstructure may be 7 area% or more have.
  • the steel material by weight, may further include 0.0005 ⁇ 0.01% B.
  • the steel material by weight, may further include one or more selected from 1.0% or less of Cu and 5.0% or less of Cr.
  • the steel material may satisfy the range of 10 to 19 mJ / m 2 in the stacked defect energy (SFE) expressed by the following relational expression 1.
  • the grain size of the austenite may be 5 ⁇ 150 ⁇ m.
  • the grain boundary in the crystal grains of the microstructure may be 80 area% or less.
  • the yield strength of the steel material is 400 MPa or more, tensile strength is 800 MPa or more, elongation is 30% or more, and Charpy impact toughness at -196 ° C may be 30 J or more (based on 5 mm thickness).
  • a method of manufacturing an austenitic high-manganese steel material having excellent yield strength in weight percent, C: 0.2 to 0.5%, Mn: 20 to 28%, Si: 0.05 to 0.5%, P: 0.03 % Or less, S: 0.005% or less, Al: 0.005 to 0.05%, reheating step of reheating the slab containing the remaining Fe and other inevitable impurities in a temperature range of 1050 to 1300 ° C; A hot rolling step of hot rolling the reheated slab to a finish rolling temperature of 800 to 1050 ° C to provide a hot rolled material; A cooling step of accelerated cooling the hot rolled material to a temperature range of 600 ° C. or less at a cooling rate of 10 to 100 ° C./s; And in the temperature range of 25 ⁇ 400 °C 0.1 to 10% of the reduction rate may include a step of weakly lowering the accelerated cooling the hot rolled material.
  • the slab by weight, may further include 0.0005 to 0.01% B.
  • the slab, by weight, may further include one or more selected from 1.0% or less of Cu and 5.0% or less of Cr.
  • the slab may satisfy the range of 10 to 19 mJ / m 2 in the stacked defect energy (SFE) expressed by the following relational expression 1.
  • the reduction ratio of the step of lowering the pressure may be 1 to 5%.
  • an austenitic high-manganese steel having excellent ductility and excellent yield strength and a method for manufacturing the same.
  • the present invention relates to an austenitic high-manganese steel material having excellent yield strength and a method for manufacturing the same, which will be described below with reference to preferred embodiments of the present invention.
  • the embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. These embodiments are provided to those skilled in the art to further detail the present invention.
  • the austenitic high-manganese steel material having excellent yield strength according to an aspect of the present invention is, by weight, C: 0.2 to 0.5%, Mn: 20 to 28%, Si: 0.05 to 0.5%, P: 0.03% or less, S: 0.005% or less, Al: 0.005 to 0.05%, balance Fe and other inevitable impurities may be included.
  • Carbon (C) is an effective element for stabilizing austenite of steel materials and securing strength by solid solution strengthening. Therefore, the present invention can limit the lower limit of the carbon (C) content to 0.2% in order to secure low-temperature toughness and strength. That is, when the carbon (C) content is less than 0.2%, the stability of austenite is insufficient to obtain a stable austenite at cryogenic temperatures, and it is easy to process organic transformation into ⁇ -martensitic and ⁇ '-martensitic due to external stress. This is because it can reduce the toughness and strength of steel materials.
  • the lower limit of the more preferable carbon (C) content may be 0.3%.
  • the carbon (C) content exceeds a certain range, the toughness of the steel may be rapidly deteriorated due to the precipitation of carbides, and the strength of the steel may be excessively high, thereby significantly reducing the workability of the steel.
  • the upper limit of the content can be limited to 0.5%.
  • the upper limit of the more preferable carbon (C) content may be 0.45%.
  • Manganese (Mn) is an important element that plays a role in stabilizing austenite, so the present invention can limit the lower limit of the manganese (Mn) content to 20% to achieve this effect. That is, the present invention can effectively increase the austenite stability because it contains 20% or more of manganese (Mn), thereby effectively suppressing the formation of ferrite, ⁇ -martensite, and ⁇ '-martensite to effectively lower the low-temperature toughness of steel. Can be secured.
  • the lower limit of the preferred manganese (Mn) content may be 22%, and the lower limit of the more preferred manganese (Mn) content may be 23%.
  • the present invention can limit the upper limit of the manganese (Mn) content to 28%.
  • the upper limit of the preferred manganese (Mn) content may be 26%, and the upper limit of the more preferred manganese (Mn) content may be 25%.
  • Silicon (Si) is an element that is indispensably added in trace amounts as a deoxidizer, such as aluminum (Al).
  • a deoxidizer such as aluminum (Al).
  • silicon (Si) is excessively added, an oxide is formed at a grain boundary to reduce high temperature ductility, and there is a fear that surface quality may be lowered by causing cracks, etc., so that the present invention has an upper limit of the silicon (Si) content. It can be limited to 0.50%.
  • an excessive cost is required to reduce the silicon (Si) content in the steel, so the present invention can limit the lower limit of the silicon (Si) content to 0.05%. Therefore, the silicon (Si) content of the present invention may be 0.05 to 0.50%.
  • Phosphorus (P) is an element that is easily segregated and causes cracking during casting or degrades weldability. Therefore, the present invention can limit the upper limit of the phosphorus (P) content to 0.03% in order to prevent deterioration of castability and deterioration of weldability. In addition, the present invention does not specifically limit the lower limit of the phosphorus (P) content, but may also limit the lower limit to 0.001% in consideration of the steelmaking burden.
  • Sulfur (S) is an element that causes hot brittle defects by inclusion formation. Therefore, the present invention can limit the upper limit of the sulfur (S) content to 0.005% to suppress the occurrence of hot embrittlement. In addition, the present invention does not specifically limit the lower limit of the sulfur (S) content, but may also limit the lower limit to 0.0005% in consideration of the steelmaking burden.
  • Aluminum (Al) is a representative element added as a deoxidizer. Therefore, the present invention can limit the lower limit of the aluminum (Al) content to 0.001%, more preferably the lower limit of the aluminum (Al) content to 0.005% to achieve this effect.
  • aluminum (Al) may form precipitates by reacting with carbon (C) and nitrogen (N), and the hot workability may be deteriorated by these precipitates, and the present invention provides an upper limit of the aluminum (Al) content. It can be limited to 0.05%.
  • the upper limit of the more preferable aluminum (Al) content may be 0.045%.
  • the austenitic high manganese steel material having excellent yield strength according to an aspect of the present invention may further include 0.0005 to 0.01% B in weight percent, and also, among Cu of 1.0% or less and Cr of 5.0% or less It may further include one or more selected.
  • Copper (Cu) 1% or less
  • Copper (Cu) is an element that stabilizes austenite together with manganese (Mn) and carbon (C), and is an element contributing to the improvement of low-temperature toughness of steel materials.
  • copper (Cu) is a very low solid solution in carbide and has a slow diffusion in austenite, it is concentrated at the interface between austenite and carbide to surround the nucleus of fine carbide to further diffuse carbon (C). It is an element that effectively suppresses the formation and growth of carbides. Therefore, copper (Cu) may be added to secure low-temperature toughness, and copper (Cr) may be added in excess of 0%.
  • the lower limit of the preferred copper (Cu) content may be 0.3%, and the lower limit of the more preferred copper (Cu) content may be 0.4%.
  • the present invention may limit the upper limit of the content of copper (Cu) to 1%.
  • the upper limit of the preferred copper (Cu) content may be 0.9%, and the upper limit of the more preferred copper (Cu) content may be 0.7%.
  • Chromium (Cr) is a winso that stabilizes austenite up to a range of an appropriate addition amount, thereby contributing to the improvement of impact toughness at low temperatures, and is employed in austenite to increase the strength of steel.
  • chromium is also an element that improves the corrosion resistance of steel materials. Therefore, chromium (Cr) may be added to achieve this effect, and chromium (Cr) may be added in excess of 0%.
  • the lower limit of the preferred chromium (Cr) content may be 1.2%, and the lower limit of the more preferred chromium (Cr) content may be 2.5%.
  • chromium (Cr) is a carbide-forming element, and is also an element that forms a carbide at the austenite grain boundary to reduce low-temperature impact, so the present invention takes into account the content relationship with carbon (C) and other elements added together
  • the upper limit of the chromium (Cr) content may be limited to 5.0%.
  • the upper limit of the preferred chromium (Cr) content may be 4.5%, and the upper limit of the more preferred chromium (Cr) content may be 4.0%.
  • Boron (B) is a grain boundary strengthening element for strengthening the austenite grain boundary, and is an element capable of effectively lowering the high temperature cracking sensitivity of steel materials by strengthening the austenite grain boundary even with a small amount added. Therefore, in order to achieve this effect, the present invention can add more than 0.0005% boron (B).
  • the lower limit of the preferred boron (B) content may be 0.001%, and the lower limit of the more preferred boron (B) content may be 0.002%.
  • the content of boron (B) exceeds a certain range, it causes segregation at the austenite grain boundary, thereby increasing the sensitivity of high temperature cracking of the steel, so the surface quality of the steel may be lowered.
  • the upper limit of the content can be limited to 0.01%.
  • the upper limit of the preferred boron (B) content may be 0.008%, and the upper limit of the more preferred boron (B) content may be 0.006%.
  • the austenitic high-manganese steel having excellent yield strength may include the remaining Fe and other unavoidable impurities in addition to the above-described components.
  • unintended impurities may be inevitably mixed from the raw material or the surrounding environment, and thus cannot be entirely excluded. Since these impurities are known to anyone skilled in the art, they are not specifically mentioned in this specification.
  • addition of effective ingredients other than the above composition is not excluded.
  • the austenitic high-manganese steel material having excellent yield strength may include at least 95% by area of austenite as a microstructure, thereby effectively securing cryogenic toughness of the steel material.
  • the average grain size of austenite may be 5 to 150 ⁇ m.
  • the average grain size of austenite that can be implemented in the manufacturing process is 5 ⁇ m or more, and when the average grain size is greatly increased, the strength of the steel material may be lowered, so the grain size of austenite may be limited to 150 ⁇ m or less.
  • the grain boundary fraction in a grain of austenitic high-manganese steel having excellent yield strength according to an aspect of the present invention may be 7 area% or more, and a preferred grain boundary fraction in grain may be 10% or more.
  • the grain boundaries in the crystal grains of the present invention may be interpreted as meaning including grain boundaries newly formed in a process under a weak pressure described later. That is, the microstructure having a predetermined grain in the steel material may be formed by a series of processes of heating, hot rolling and cooling the slab, and in some cases, a very small amount of strain may be formed in one grain.
  • the grain boundaries in the grain of the present invention include grain boundaries newly introduced into the grains through the weak pressure process.
  • the grain boundaries in the grain of the present invention may be interpreted as a concept including both high and small angle grain boundaries. Since the austenitic high manganese steel of the present invention is manufactured by introducing a process under weak pressure, grain boundaries within 7 area% or more, preferably grain boundaries within 10% or more, are formed, thereby effectively securing the yield strength of the steel. You can.
  • the present invention can limit the upper limit of the intergranular fraction in the grain to 80 area% in order to achieve the yield strength and elongation of the steel material.
  • the upper limit of the grain boundary fraction in a more preferable crystal grain may be 60 area%.
  • the austenitic high manganese steel material having excellent yield strength may include carbide and / or ⁇ -martensite as a possible structure in addition to austenite.
  • carbide and / or ⁇ -martensite exceeds a certain level, the toughness and ductility of the steel may be rapidly reduced.
  • the fraction of carbide and / or ⁇ -martensite is less than 5 area%. Can be limited.
  • the austenitic high manganese steel having excellent yield strength limits the content range of the alloy component so that the stacked fault energy (SFE) represented by the following relational expression 1 satisfies the range of 10 to 19 mJ / m 2 You can.
  • SFE stacked fault energy
  • the stacking fault energy (SFE) represented by the relational expression 1 is less than 10 mJ / m 2 , ⁇ -martensite and ⁇ '-martensite may be formed, and particularly, when ⁇ '-martensite occurs, low-temperature toughness decreases rapidly. Problems can occur.
  • the more preferable stacked defect energy (SFE) may be 11 mJ / m 2 or more.
  • the stability of austenite increases as the stacking fault energy (SFE) expressed by the relational expression 1 increases, but when the value exceeds 19 mJ / m 2 , it is not preferable in view of the efficiency of adding an alloying element.
  • the upper limit of the more preferable stacked defect energy (SFE) may be 16 mJ / m 2 .
  • the austenitic high manganese steel having excellent yield strength has a yield strength of 400 MPa or more, a tensile strength of 800 MPa or more, an elongation of 30% or more, and Charpy impact toughness of 30 J or more (based on 5 mm thickness) at -196 ° C. Therefore, it is possible to provide a structural steel material particularly suitable for cryogenic environments.
  • the method for manufacturing austenitic high manganese steel having excellent yield strength of the present invention includes a reheating step of reheating a slab in a temperature range of 1050 to 1300 ° C; A hot rolling step of hot rolling the reheated slab to a finish rolling temperature of 800 to 1050 ° C to provide a hot rolled material; A cooling step of cooling the hot rolled material to a temperature range of 600 ° C. or less at a cooling rate of 1 to 100 ° C .; And in the temperature range of 25 ⁇ 400 °C may include a step of lowering the pressure to lower the cooled hot rolled material at a reduction rate of 0.1 to 10%.
  • the slab provided in the manufacturing method of the present invention corresponds to the steel composition of the austenitic high-manganese steel described above, the steel composition of the slab and the description of the stacked defect energy (SFE) are described in the above-described austenitic high-manganese steel. It is replaced by a description of the steel composition and stacked fault energy (SFE).
  • SFE stacked defect energy
  • the slab provided with the above-described steel composition can be reheated in a temperature range of 1050 to 1300 ° C. If the reheating temperature is less than a certain range, a problem that excessive rolling load may occur during hot rolling or a problem that the alloying component is not sufficiently dissolved may occur, and the present invention limits the lower limit of the slab reheating temperature range to 1050 ° C. You can. On the other hand, when the reheating temperature exceeds a certain range, there is a fear that the grains may grow excessively and the strength may decrease or the hot rolling property of the steel material may deteriorate due to reheating exceeding the solidus temperature of the steel material. The upper limit of the reheating temperature range can be limited to 1300 ° C.
  • the hot rolling process includes a rough rolling process and a finish rolling process, and the reheated slab may be hot rolled and provided as a hot rolled material.
  • the hot finish rolling is preferably carried out in a temperature range of 800 ⁇ 1050 °C. If the hot finish rolling temperature is less than a certain range, excessive rolling load due to an increase in the rolling load may be a problem, and if the hot finish rolling temperature exceeds a certain range, the grains grow coarsely and the target strength cannot be obtained.
  • the rolling reduction during hot rolling can be adjusted to a predetermined range according to the thickness of the desired steel.
  • the hot rolled hot rolled material may be cooled to a cooling stop temperature of 600 ° C. or less at a cooling rate of 1 to 100 ° C./s. If the cooling rate is less than a certain range, the ductility of the steel may be reduced due to carbides precipitated at the grain boundary during cooling, and thus deterioration of abrasion resistance may be a problem. Therefore, the present invention can limit the cooling rate of the hot rolled material to 1 ° C / s or more. have. The preferred lower cooling rate may be 10 ° C / s, and the cooling method may be accelerated cooling.
  • the present invention sets the upper limit of the cooling rate to 100 ° C. Can be limited to / s.
  • the present invention limits the cooling stop temperature to 600 ° C. or less. You can.
  • a process of weak rolling at a rolling rate of 0.1 to 10% in a temperature range of 25 to 400 ° C may be involved with respect to the hot rolled material being cooled or the hot rolled material that has been cooled.
  • the present invention can limit the lower limit of the temperature range of the weak pressure process to 25 ° C, and rolling
  • the lower limit of the temperature range of the process under weak pressure which is more preferable in terms of load reduction, may be 100 ° C.
  • the present invention can limit the upper limit of the temperature range of the process under the weak pressure to 400 ° C.
  • the present invention can limit the reduction ratio under a weak pressure to 0.1% or more in order to achieve the desired strength improving effect.
  • the lower limit of the preferred reduction ratio under weak pressure may be 0.5%, and the lower limit of the more preferred lower reduction ratio may be 1.0%.
  • the present invention can limit the rolling reduction under weak pressure to 10% or less in order to prevent the elongation of the steel material from falling.
  • the upper limit of the preferred reduction ratio under weak pressure may be 8%, and the upper limit of the lower preferred reduction ratio under weak pressure may be 5%.
  • the austenitic high manganese steel material prepared as described above contains 95% by area or more of austenite as a microstructure, and the grain boundary in the crystal grains may be 7% by area or more, yield strength of 400MPa or more, tensile strength of 800MPa or more, 30% or more Elongation and Charpy impact toughness of 30J or more (based on 5mm thickness) based on -196 ° C may be provided.
  • a slab provided with the alloy composition of Table 1 was prepared, and each specimen was manufactured by applying the manufacturing process of Table 2.
  • SFE in Table 1 refers to the lamination defect energy (mJ / m 2 ) calculated through Equation 1, and specimens 1, 6, and 11 in Table 2 refer to specimens in which a weak pressure is not applied.
  • the microstructure, tensile properties and impact toughness of each specimen were evaluated, and the results are shown in Table 3.
  • the microstructure of each specimen was observed using SEM and EBSD, and the grain size fraction in the mouth was measured using the EBSD Image Quality Map.
  • Tensile properties were tested at room temperature in accordance with ASTM A370, and impact toughness was measured at -196 ° C by processing into impact specimens of 5 mm thickness in accordance with the conditions of the same standard.
  • FIG. 1 is a result of observing the microstructure of specimen 1 using EBSD.
  • 1 (a) is an IPF map, and showing the same brightness (or saturation) within a boundary means one grain, and indicating different brightness (or saturation) means different crystal orientations, that is, different grains. do.
  • FIG. 1 (b) is an IQ map for the same tissue as in FIG. 1 (a), and it can be confirmed that almost no other modified tissue exists in the grain.
  • FIG. 2 is a result of observing the microstructure of specimen 10 using EBSD.
  • FIG. 2 (a) is also an IPF map, and indicating the same brightness (or saturation) within a boundary means one grain, and indicating different brightness (or saturation) means different crystal orientations, that is, different grains. do.
  • FIG. 2 (b) is an IQ map for the same tissue as FIG. 2 (a), and it can be confirmed that a modified tissue occurred in the grain.
  • FIG. 2 (c) shows the grain boundary angle according to the arrow length of FIG. 2 (b), and it can be confirmed that new grain boundaries having incineration and elevation characteristics inside the grains from lines A, B, and C were generated. That is, by (a) to (c) of FIG. 2, it can be seen that, unlike the specimen 1, the specimen 10 is formed with a large amount of new grain boundaries in the grain boundary through a process under weak pressure.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

Selon un aspect, cette invention concerne un acier austénitique à haute teneur en manganèse ayant une haute limite d'élasticité, comprenant, en % en poids : 0,2 % à 0,5 % de C, 20 % à 28 % de Mn, 0,05 % à 0,5 % de Si, 0,03 % ou moins de P, 0,005 % ou moins de S, 0,005 % à 0,05 % d'Al, le reste étant du Fe et les inévitables impuretés ; et 95 % en surface ou plus d'austénite en tant que microstructure, la fraction de limite de grain dans les grains cristallins de la microstructure pouvant être supérieure ou égale à 7 % en surface.
PCT/KR2019/014175 2018-10-25 2019-10-25 Acier austénitique à haute teneur en manganèse ayant une haute limite d'élasticité et son procédé de fabrication WO2020085852A1 (fr)

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CN201980069181.4A CN112912530B (zh) 2018-10-25 2019-10-25 屈服强度优异的奥氏体高锰钢材及其制备方法
EP19876536.4A EP3872215A4 (fr) 2018-10-25 2019-10-25 Acier austénitique à haute teneur en manganèse ayant une haute limite d'élasticité et son procédé de fabrication

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KR20180128500 2018-10-25
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KR1020190118926A KR102290780B1 (ko) 2018-10-25 2019-09-26 항복강도가 우수한 오스테나이트계 고망간 강재 및 그 제조방법

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113388787A (zh) * 2021-06-27 2021-09-14 上交大(徐州)新材料研究院有限公司 一种高强韧耐磨钢及其纳米孪晶增强增韧化的制备方法

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JPS62270721A (ja) * 1986-05-19 1987-11-25 Kobe Steel Ltd 極低温用高Ｍｎオ−ステナイトステンレス鋼の製造方法
KR100742823B1 (ko) * 2005-12-26 2007-07-25 주식회사 포스코 표면품질 및 도금성이 우수한 고망간 강판 및 이를 이용한도금강판 및 그 제조방법
KR100851158B1 (ko) * 2006-12-27 2008-08-08 주식회사 포스코 충돌특성이 우수한 고망간형 고강도 강판 및 그 제조방법
KR20100118238A (ko) * 2009-04-28 2010-11-05 연세대학교 산학협력단 고강도 및 고연성을 갖는 고망간 질소 함유 강판 및 그 제조방법
US20110308673A1 (en) * 2008-11-12 2011-12-22 Voestalpine Stahl Gmbh Manganese steel strip having an increased phosphorous content and process for producing the same
KR20150075324A (ko) 2013-12-25 2015-07-03 주식회사 포스코 항복강도가 우수한 오스테나이트계 고망간강 및 그 제조방법

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62270721A (ja) * 1986-05-19 1987-11-25 Kobe Steel Ltd 極低温用高Ｍｎオ−ステナイトステンレス鋼の製造方法
KR100742823B1 (ko) * 2005-12-26 2007-07-25 주식회사 포스코 표면품질 및 도금성이 우수한 고망간 강판 및 이를 이용한도금강판 및 그 제조방법
KR100851158B1 (ko) * 2006-12-27 2008-08-08 주식회사 포스코 충돌특성이 우수한 고망간형 고강도 강판 및 그 제조방법
US20110308673A1 (en) * 2008-11-12 2011-12-22 Voestalpine Stahl Gmbh Manganese steel strip having an increased phosphorous content and process for producing the same
KR20100118238A (ko) * 2009-04-28 2010-11-05 연세대학교 산학협력단 고강도 및 고연성을 갖는 고망간 질소 함유 강판 및 그 제조방법
KR20150075324A (ko) 2013-12-25 2015-07-03 주식회사 포스코 항복강도가 우수한 오스테나이트계 고망간강 및 그 제조방법

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113388787A (zh) * 2021-06-27 2021-09-14 上交大(徐州)新材料研究院有限公司 一种高强韧耐磨钢及其纳米孪晶增强增韧化的制备方法

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