EP3872214A1 - Manganreicher stahl mit ausgezeichneten sauerstoffschneideigenschaften und herstellungsverfahren dafür - Google Patents

Manganreicher stahl mit ausgezeichneten sauerstoffschneideigenschaften und herstellungsverfahren dafür Download PDF

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EP3872214A1
EP3872214A1 EP19876472.2A EP19876472A EP3872214A1 EP 3872214 A1 EP3872214 A1 EP 3872214A1 EP 19876472 A EP19876472 A EP 19876472A EP 3872214 A1 EP3872214 A1 EP 3872214A1
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Prior art keywords
steel
high manganese
less
cutting
manganese steel
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English (en)
French (fr)
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EP3872214A4 (de
Inventor
Un-Hae LEE
Dong-Ho Lee
Won-Tae Cho
Soon-Gi Lee
Chang-Sik Choi
Sang-Deok Kang
Young-Deok JUNG
Bo-Sung Kim
Jeong-Hun SEOK
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Posco Holdings Inc
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Posco Co Ltd
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Priority claimed from PCT/KR2019/014184 external-priority patent/WO2020085855A1/ko
Publication of EP3872214A1 publication Critical patent/EP3872214A1/de
Publication of EP3872214A4 publication Critical patent/EP3872214A4/de
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    • 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
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
    • 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
    • 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
    • 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
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following 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
    • 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
    • C22C38/06—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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • 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
    • 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
    • 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
    • C21D2261/00—Machining or cutting being involved

Definitions

  • the present disclosure relates to a high manganese steel and a manufacturing method therefor, and more particularly, to an austenitic high manganese steel having excellent oxygen cutting properties and a manufacturing method therefor.
  • An austenitic high manganese steel is characterized by high toughness because austenite is stabilized even at room temperature by adjusting contents of manganese (Mn) and carbon (C), which are elements enhancing the stability of the austenite.
  • Austenite which is a paramagnetic material, has low permeability with excellent nonmagnetic properties when compared to ferrite.
  • the austenitic high manganese steel has a permeability of 1.02 or less, whereas a material generally used for a transformer, a distribution board, or the like has a permeability of 1.05 or less.
  • the austenitic high manganese steel has superior nonmagnetic properties as compared to the conventional material.
  • the high manganese steel having austenite as a main structure thereof is technically advantageous in that its low-temperature toughness is excellent because it has ductile fracture characteristics at a low temperature.
  • the austenitic high manganese steel In order to use the austenitic high manganese steel as a structure, it is necessary to cut and process the material through oxygen cutting or the like.
  • the high manganese steel contains alloy components in a large amount, resulting in a problem that sparks occurring in oxygen cutting work may cause a cut surface in an inferior state. That is, in order to improve the cutting properties, it is necessary to pre-heat the steel or to adjust a cutting speed to a low level, which is not preferable in terms of productivity.
  • an austenitic high manganese steel having economical and effective oxygen cutting characteristics.
  • Patent Document 1 Korean Patent Laid-Open Publication No. 10-2010-0064473 (published on June 15, 2010 )
  • An aspect of the present disclosure is to provide a high manganese steel having excellent oxygen cutting properties and a manufacturing method therefor.
  • a high manganese steel having excellent oxygen cutting properties may contain, by wt%, 0.1 to 0.5% of carbon (C), 20 to 26% of manganese (Mn), 0. 05 to 0.4% of silicon (Si), 2.0% or less of aluminum (Al), and 4% or less of chromium (Cr), with the balance of Fe and other inevitable impurities, wherein the high manganese steel has a cutting sensitivity (Sc) of 430 or more when calculated according to Relational Equation 1 below, and contains 95 area% or more of austenite as a microstructure.
  • Cutting sensitivity Sc 1742 ⁇ 662 * C ⁇ 19.2 * Mn + 1.6 * Al ⁇ 140 * Cr
  • the steel may further contain, by wt%, 0.0005 to 0.01% of boron (B).
  • the steel may have a permeability of 1.02 or less.
  • the steel may have a yield strength of 240 MPa or more, a tensile strength of 720 MPa or more, and an elongation of 25% or more.
  • a cut surface of the steel may have an average surface roughness of 0.5 mm or less.
  • a method for manufacturing a high manganese steel having excellent oxygen cutting properties may include: reheating a slab at a temperature ranging from 1050 to 1300°C, the slab containing, by wt%, 0.1 to 0.5% of carbon (C), 20 to 26% of manganese (Mn), 0.05 to 0.4% of silicon (Si), 2.0% or less of aluminum (Al), and 4% or less of chromium (Cr), with the balance of Fe and other inevitable impurities, and the slab having a cutting sensitivity (Sc) of 430 or more when calculated according to Relational Expression 1 below; hot-rolling the reheated slab at a finish rolling temperature of 800 to 1050°C to provide a hot-rolled material; and cooling the hot-rolled material to a temperature of 600°C or less at a cooling rate of 1 to 100°C/s.
  • Cutting sensitivity Sc 1742 ⁇ 662 * C ⁇ 19.2 * Mn + 1.6 * Al ⁇ 140 * Cr
  • the slab may further contain, by wt%, 0.0005 to 0.01% of boron (B).
  • an austenitic high manganese steel having excellent oxygen cutting properties and a manufacturing method therefor can be provided.
  • FIG. 1 (a) is a photograph of a surface cut by oxygen cutting together with whether or not sparks occur at the time of oxygen cutting in Example 2
  • FIG. 1 (b) is a photograph of a surface cut by oxygen cutting together with whether or not sparks occur at the time of oxygen cutting in Comparative Example 2.
  • the present disclosure relates to a high manganese steel having excellent oxygen cutting properties and a manufacturing method therefor, which will be described below with reference to preferred exemplary embodiments in the present disclosure.
  • the exemplary embodiments in the present disclosure may be modified in various forms, and the scope of the present disclosure should not be construed as being limited to the exemplary embodiments described below. These exemplary embodiments are provided to describe the present disclosure in more detail to those having ordinary knowledge in the relevant art to which the present disclosure pertains.
  • a high manganese steel having excellent oxygen cutting properties may contain, by wt%, 0.1 to 0.5% of carbon (C), 20 to 26% of manganese (Mn), 0.05 to 0.4% of silicon (Si), 2.0% or less of aluminum (Al), and 4% or less of chromium (Cr), with the balance of Fe and other inevitable impurities.
  • Carbon (C) 0.1 to 0.5%
  • Carbon (C) is an element that is effective in stabilizing austenite in the steel and securing strength through solid solution strengthening.
  • a lower limit of the carbon (C) content may be limited to a predetermined range to secure low-temperature toughness and strength. That is, if the carbon (C) content is lower than a predetermined level, stability of austenite may be insufficient, thereby not obtaining stable austenite at room temperature, and austenite may be easily transformed into ⁇ -martensite and ⁇ '-martensite by external stress through strain induced transformation, thereby decreasing the toughness and strength of the steel. Therefore, in the present disclosure, the lower limit of the carbon (C) content may be limited to 0.1%.
  • the lower limit of the carbon (C) content may be preferably 0.15%, more preferably 0.17%.
  • an upper limit of the carbon (C) content may be limited to 0.5%.
  • the upper limit of the carbon (C) content may be preferably 0.47%, more preferably 0.45%.
  • Manganese (Mn) 20 to 26%
  • Manganese (Mn) is an important element serving to stabilize austenite.
  • a lower limit of the manganese (Mn) content may be limited to 20% in the present disclosure. That is, when 20% or more of manganese (Mn) is contained according to the present disclosure, stability of austenite may be effectively increased, and accordingly, formation of ferrite, ⁇ -martensite, and ⁇ '-martensite is suppressed, thereby effectively securing the nonmagnetic properties and low-temperature toughness of the steel.
  • the manganese (Mn) content exceeds a predetermined range, the effect thereof in increasing the stability of the austenite may saturated, while a manufacturing cost greatly increases and internal oxidation occurs excessively during hot rolling, resulting in an inferior surface quality.
  • an upper limit of the manganese (Mn) content may be limited to 26%. Therefore, the manganese (Mn) content of the present disclosure may be in the range of 20 to 26%, more preferably 20 to 24%.
  • Silicon (Si) is an element which is inevitably added in a very small amount as a deoxidizer, like aluminium (Al). If silicon (Si) is excessively added, oxides may be formed along grain boundaries, resulting in a decrease in high-temperature ductility, cracks or the like may be caused, resulting in a deterioration in surface quality. Thus, in the present disclosure, an upper limit of the silicon (Si) content may be limited to 0.4%. More preferably, the upper limit of the silicon (Si) content may be 0.3%. On the other hand, in order to decrease the silicon (Si) content in the steel, an excessive cost may be incurred. Thus, in the present disclosure, a lower limit of the silicon (Si) content may be limited to 0.05%. More preferably, the lower limit of the silicon (Si) content may be 0.1%.
  • Aluminum (Al) 2.0 or less
  • Aluminum (Al) is a representative element added as a deoxidizer. However, aluminum (Al) may form precipitates by reacting with carbon (C) and nitrogen (N), and these precipitates may cause a deterioration in hot workability. Thus, in the present disclosure, an upper limit of the aluminum (Al) content may be limited to 2.0%. The aluminum (Al) content may be preferably in the range of 0.01 to 2.0%, more preferably 0.01 to 1.95%.
  • Chromium (Cr) 4% or less
  • Chromium (Cr) is an element dissolved in austenite to increase the strength of the steel, contributing to an improvement in nonmagnetic properties by stabilizing the austenite when added in an appropriate content range.
  • chromium (Cr) is an element that also improves the corrosion resistance of the steel.
  • chromium (Cr) may be added in the present disclosure.
  • chromium (Cr) increases a temperature for melting oxides at the time of oxygen cutting, and tends to cause inferior oxygen cutting properties as chromium (Cr) is added in a higher content.
  • an upper limit of the chromium (Cr) content may be limited to 4%. More preferably, the upper limit of the chromium (Cr) content may be 3.5%.
  • the balance other than the above-described components may be Fe and other inevitable impurities. Meanwhile, unintended impurities may be inevitably mixed from raw materials or surrounding environments in a general manufacturing process, and the impurities cannot be completely excluded. Such impurities are known to any person having ordinary knowledge in the art, and thus, all descriptions thereof will not be particularly provided in the present specification. Furthermore, addition of effective components other than the above-described composition is not entirely excluded.
  • the high manganese steel having excellent oxygen cutting properties may further contain, by wt%, 0.0005 to 0.01% of boron (B), and may contain one or more of 0.03% or less of phosphorus (P), 0.05% or less of sulfur (S), and 0.02% or less of nitrogen (N).
  • B boron
  • P phosphorus
  • S sulfur
  • N nitrogen
  • Boron (B) which is an element strengthening austenite grain boundaries, is an element capable of effectively lowering the hot cracking sensitivity of the steel by strengthening the austenite grain boundaries even when added in a small amount.
  • a lower limit of the boron (B) content may be limited to 0.0005% in the present disclosure. More preferably, the lower limit of the boron (B) content may be 0.001%.
  • an upper limit of the boron (B) content may be limited to 0.01%. More preferably, the upper limit of the boron (B) content may be 0.006%.
  • Phosphorus (P) is not only an element that is inevitably introduced into the steel but also an element that is easily segregated, thereby causing a crack during casting or a deterioration in weldability.
  • an upper limit of the phosphorus (P) content may be limited to 0.03% in present disclosure. More preferably, the upper limit of the phosphorus (P) content may be 0.02%.
  • Sulfur (S) is not only an element that is also inevitably introduced into the steel but also an element that forms an inclusion, thereby inducing a hot embrittlement defect.
  • an upper limit of the sulfur (S) content may be limited to 0.05% in the present disclosure. More preferably, the upper limit of the sulfur (S) content may be 0.02%.
  • Nitrogen (N) is not only an element that is also inevitably introduced into the steel but also an element that contributes to solid solution strengthening. However, if the nitrogen (N) content is excessive, there is a problem that coarse nitrides may be formed, thereby decreasing the strength of the steel. Thus, in the present disclosure, an upper limit of the nitrogen (N) content may be limited to 0.02%.
  • the high manganese steel having excellent oxygen cutting properties may have a cutting sensitivity (Sc) of 430 or more when calculated according to Relational Equation 1 below. More preferably, the cutting sensitivity (Sc) calculated according to Relational Equation 1 below may be 460 or more.
  • Cutting sensitivity Sc 1742 ⁇ 662 * C ⁇ 19.2 * Mn + 1.6 * Al ⁇ 140 * Cr
  • the inventors of the present disclosure have conducted in-depth research concerning the oxygen cutting properties of the high manganese steel, and have found that aluminum (Al) is an element positively affecting the oxygen cutting properties of the high manganese steel, whereas carbon (C), manganese (Mn) and chromium (Cr) are elements negatively affecting the oxygen cutting properties of the high manganese steel.
  • the inventors of the present disclosure have conducted research on a correlation between the carbon (C), manganese (Mn), chromium (Cr), and aluminum (Al) contents, and have confirmed that when the cutting sensitivity (Sc) represented by Relational Expression 1 is at a predetermined level or higher, the high manganese steel has excellent oxygen cutting properties.
  • the high manganese steel having excellent oxygen cutting properties according to this aspect of the present disclosure has alloy composition contents controlled so that the cutting sensitivity (Sc) according to Relational Expression 1 satisfies 430 or more. Accordingly, a surface of the steel cut at the time of oxygen cutting may be managed to have an average surface roughness at a level of 0.5 mm or less.
  • the high manganese steel having excellent oxygen cutting properties may contain 95 area% or more of austenite as a microstructure, thereby securing the nonmagnetic properties and the low-temperature properties of the steel effectively.
  • the austenite may have an average grain size of 5 to 150 ⁇ m.
  • the average grain size of the austenite implementable in the manufacturing process is 5 ⁇ m or more, and the grain size of the austenite may be limited to 150 ⁇ m or less because there is concern that a great increase in average grain size thereof may cause a decrease in strength of the steel.
  • the austenitic high manganese steel having excellent oxygen cutting properties may contain carbides and/or ⁇ -martensite as a structure that may exist therein in addition to the austenite. If the fraction of the carbides and/or ⁇ -martensite exceeds a predetermined level, the toughness and the ductility of the steel may rapidly deteriorate. Thus, in the present disclosure, the fraction of the carbides and/or ⁇ -martensite may be limited to 5 area% or less.
  • the steel may have an excellent cut surface at the time of oxygen cutting. That is, the occurrence of sparks can be minimized at the time of oxygen cutting, thereby minimizing the melting of the steel, which is followed by a phenomenon in which the cut surface is uneven.
  • the high manganese steel having excellent oxygen cutting properties according to an aspect of the present disclosure is capable of effectively preventing a decrease in cutting speed at the time of oxygen cutting, thereby optimizing the process in terms of efficiency and maximizing productivity.
  • the high manganese steel having excellent oxygen cutting properties may have a permeability of 1.02 or less, a yield strength of 240 MPa or more, a tensile strength of 720 MPa or more, and an elongation of 25% or more.
  • a method for manufacturing a high manganese steel having excellent oxygen cutting properties may include: reheating a slab at a temperature ranging from 1050 to 1300°C, the slab containing, by wt%, 0.1 to 0.5% of carbon (C), 20 to 26% of manganese (Mn), 0.05 to 0.4% of silicon (Si), 2.0% or less of aluminum (Al), and 4% or less of chromium (Cr), with the balance of Fe and other inevitable impurities, and the slab having a cutting sensitivity (Sc) of 430 or more when calculated according to Relational Expression 1 below; hot-rolling the reheated slab at a finish rolling temperature of 800 to 1050°C to provide a hot-rolled material; and cooling the hot-rolled material to a temperature of 600°C or less at a cooling rate of 1 to 100°C/s.
  • Cutting sensitivity Sc 1742 ⁇ 662 * C ⁇ 19.2 * Mn + 1.6 * Al ⁇ 140 * Cr
  • the slab may further contain, by wt%, 0.0005 to 0.01% of boron (B), and may contain one or more of 0.03% or less of phosphorus (P), 0.05% or less of sulfur (S), and 0.02% or less of nitrogen (N).
  • B boron
  • P phosphorus
  • S sulfur
  • N nitrogen
  • the steel composition of the slab provided in the manufacturing method according to the present disclosure corresponds to the above-described composition of the high manganese steel having excellent oxygen cutting properties.
  • the description of the steel composition of the slab is replaced with the above description for the composition of the steel.
  • the slab provided with the above-described steel composition may be reheated at a temperature ranging from 1050 to 1300°C. If the reheating temperature is lower than the predetermined range, there may be a problem that an excessive rolling load is applied during hot rolling, or a problem that an alloy component is not sufficiently dissolved. Thus, in the present disclosure, a lower limit of the slab reheating temperature may be limited to 1050°C. On the other hand, if the reheating temperature exceeds the predetermined range, grains may excessively grow, thereby decreasing strength, or the reheating temperature may be higher than the solidus temperature of the steel, thereby causing a deterioration in hot rolling properties of the steel. Thus, in the present disclosure, an upper limit of the slab reheating temperature may be limited to 1300°C.
  • the hot rolling may include rough rolling and finish rolling, and the reheated slab may be hot-rolled and provided as a hot-rolled material.
  • the hot finish rolling is preferably performed at a temperature ranging from 800 to 1050°C. If the hot finish rolling temperature is lower than the predetermined range, there may be a problem that a rolling load increases, resulting in an excessive rolling load. If the hot finish rolling temperature exceeds the predetermined range, grains may grow coarsely and an intended degree of strength may not be obtained.
  • the hot-rolled material obtained through hot rolling 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 lower than the predetermined range, there may be a problem that carbides precipitated along grain boundaries during cooling decrease the ductility of the steel, resulting in a deterioration in wear resistance. Thus, in the present disclosure, the cooling rate of the hot-rolled material may be limited to 1°C/s or more. More preferably, a lower limit of the cooling rate may be 10°C/s, and accelerated cooling may be applied.
  • an upper limit of the cooling rate may be limited to 100°C/s in the present disclosure, taking into account that it is generally difficult to implement a cooling rate exceeding 100°C/s during cooling due to the characteristics of the facility.
  • the cooling stop temperature may be limited to 600°C or less.
  • the high manganese steel having excellent oxygen cutting properties that is manufactured as described above may contain 95 area% or more of austenite as a microstructure and have a permeability of 1.02 or less, a yield strength of 240 MPa or more, a tensile strength of 720 MPa or more, and an elongation of 25% or more. As a result, a decrease in productivity can be effectively prevented in the oxygen cutting process while the steel has an excellent cut surface at the time of oxygen cutting.
  • a specimen was prepared by performing accelerated cooling to the hot-rolled material to a cooling stop temperature of 100°C at a cooling rate of 20°C/s. For each specimen, a yield strength, a tensile strength, and an elongation were measured. The results are shown in Table 2 below together with a permeability, a maximum cutting speed, and a cut surface state.
  • the maximum cutting speed refers to a maximum cutting speed applicable when oxygen cutting is performed at an average gas pressure of 0.7 MPa.
  • Score 1 refers to a case in which a base material is melted during oxygen cutting and also a cut surface has an average surface roughness of more than 0.5 mm
  • score 1.5 refers to a case in which a base material is partially melted during oxygen cutting but a cut surface has an average surface roughness of 0.5 mm or less
  • score 1 refers to a case in which a base material is not melted during oxygen cutting and also a cut surface has an average surface roughness of 0.5 mm or less.
  • a cutting property index in Table 2 refers to a value obtained by multiplying the maximum cutting speed by the cut surface score for each specimen.
  • Example 1 Classification Alloy composition (wt%) Relational Expression 1 C Mn Si P S Al Cr N
  • Example 1 0.41 21.7 0.27 0.017 0.003 0.013 2.01 0.013 772.6
  • Example 2 0.18 22.3 0.14 0.019 0.010 1.80 0.00 0.013 1197.6
  • Example 3 0.44 24.6 0.26 0.019 0.007 0.020 3.45 0.018 495.4
  • Example 4 0.18 21.8 0.21 0.016 0.003 0.026 2.00 0.016 924.3
  • Example 5 0.41 21.8 0.22 0.019 0.003 0.016 1.95 0.013 779.0
  • Example 6 0.40 21.6 0.20 0.018 0.003 0.025 0.00 0.014 1062.5
  • Example 7 0.41 21.9 0.21 0.019 0.003 0.027 4.00 0.016 490.1
  • Example 8 0.39 22.3 0.15 0.018 0.009 1.93 1.92 0.016 789.9
  • Example 9 0.2 22 0.2 0.018 0.00
  • a cut surface has an average surface roughness of 0.5 mm or less and also a cutting property index is 400 or more, indicating superior oxygen cutting properties, whereas in Comparative Examples 1 to 3, which do not satisfy the scope of the present disclosure, a cut surface has an average surface roughness of more than 0.5 mm and also a cutting property index is about 300, indicating inferior oxygen cutting properties.
  • FIG. 1 (a) is a photograph of a surface cut by oxygen cutting together with whether or not sparks occur at the time of oxygen cutting in Example 2
  • FIG. 1 (b) is a photograph of a surface cut by oxygen cutting together with whether or not sparks occur at the time of oxygen cutting in Comparative Example 2.
  • FIGS. 1 (a) and 1 (b) it can be confirmed that the cut surface is excellent in Example 2, whereas a base material is melted due to excessive sparks occurring at the time of oxygen cutting, resulting in an uneven cut surface, in Comparative Example 2.

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EP19876472.2A 2018-10-25 2019-10-25 Manganreicher stahl mit ausgezeichneten sauerstoffschneideigenschaften und herstellungsverfahren dafür Pending EP3872214A4 (de)

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PCT/KR2019/014184 WO2020085855A1 (ko) 2018-10-25 2019-10-25 산소 절단성이 우수한 고망간 강재 및 그 제조방법

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JPS593539B2 (ja) * 1980-01-08 1984-01-24 日本鋼管株式会社 快削性高マンガン非磁性鋼
JPS621823A (ja) * 1985-06-25 1987-01-07 Kobe Steel Ltd 被削性にすぐれた高Ｍｎ非磁性鋼の製造方法
FR2857980B1 (fr) * 2003-07-22 2006-01-13 Usinor Procede de fabrication de toles d'acier austenitique fer-carbone-manganese, a haute resistance, excellente tenacite et aptitude a la mise en forme a froid, et toles ainsi produites
EP1878811A1 (de) * 2006-07-11 2008-01-16 ARCELOR France Verfahren zur herstellung eines eisen-kohlenstoff-mangan austenitischer stahlblehs mit hervorragender verzögerter bruchfestigkeit und bleh folglich hergestellt
KR100985286B1 (ko) * 2007-12-28 2010-10-04 주식회사 포스코 내지연파괴 특성이 우수한 고강도 고망간강 및 제조방법
KR101068401B1 (ko) 2008-12-05 2011-10-04 김산 산소절단 장치
JP5618932B2 (ja) * 2011-07-22 2014-11-05 株式会社神戸製鋼所 非磁性鋼線材又は棒鋼、及びその製造方法
JP2013023742A (ja) * 2011-07-22 2013-02-04 Kobe Steel Ltd 非磁性鋼線材又は棒鋼
WO2017111510A1 (ko) * 2015-12-23 2017-06-29 주식회사 포스코 열간 가공성이 우수한 비자성 강재 및 그 제조방법
KR101889187B1 (ko) * 2015-12-23 2018-08-16 주식회사 포스코 열간 가공성이 우수한 비자성 강재 및 그 제조방법
CN107620010A (zh) * 2017-10-18 2018-01-23 舞阳钢铁有限责任公司 一种低屈强比高韧性高锰钢板及其生产方法

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