EP3872217A1 - Acier inoxydable austénitique cryogénique à haute teneur en manganèse présentant une excellente qualité de surface et procédé de fabrication associé - Google Patents

Acier inoxydable austénitique cryogénique à haute teneur en manganèse présentant une excellente qualité de surface et procédé de fabrication associé Download PDF

Info

Publication number
EP3872217A1
EP3872217A1 EP19877327.7A EP19877327A EP3872217A1 EP 3872217 A1 EP3872217 A1 EP 3872217A1 EP 19877327 A EP19877327 A EP 19877327A EP 3872217 A1 EP3872217 A1 EP 3872217A1
Authority
EP
European Patent Office
Prior art keywords
less
high manganese
manganese steel
rolling
slab
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19877327.7A
Other languages
German (de)
English (en)
Other versions
EP3872217A4 (fr
Inventor
Sung-Kyu Kim
Yu-Mi Ha
Dong-Ho Lee
Un-Hae LEE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Posco Holdings Inc
Original Assignee
Posco Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Posco Co Ltd filed Critical Posco Co Ltd
Priority claimed from PCT/KR2019/014170 external-priority patent/WO2020085851A1/fr
Publication of EP3872217A1 publication Critical patent/EP3872217A1/fr
Publication of EP3872217A4 publication Critical patent/EP3872217A4/fr
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0231—Warm 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
    • C21D8/0263—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
    • 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
    • C22C38/20—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
    • C22C38/32—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
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite

Definitions

  • the present disclosure relates to a cryogenic austenitic high manganese steel appropriate for a fuel tank, a storage tank, a ship membrane, a transport pipe, and the like, for storage and transport of liquefied petroleum gas, liquefied natural gas and the like, and a manufacturing method therefor, and more particularly, to a cryogenic austenitic high manganese steel in which surface quality is effectively secured by suppressing formation of grooves in a surface, and a manufacturing method therefor.
  • An austenitic high manganese (Mn) steel has high toughness because an austenite phase is stable, even at room temperature or cryogenic temperature, by adjusting contents of manganese (Mn) and carbon (C) , which are elements that increase phase stability of austenite. Therefore, the austenitic high manganese (Mn) steel may be used as a material of a fuel tank, a storage tank, a ship membrane, a transport pipe, and the like, for storage and transport of liquefied petroleum gas, liquefied natural gas and the like requiring cryogenic properties.
  • the high manganese (Mn) steel contains a large amount of manganese (Mn) , which has a strong oxidation tendency, some of grain boundary oxidations formed at the time of reheating a slab are removed as scale, but some of the grain boundary oxidations may grow into cracks at the time of hot rolling and remain as surface flaws on a surface of a product. Therefore, at the time of manufacturing the high manganese (Mn) steel, a process of grinding the surface of the product is necessarily involved, which is not preferable in terms of economic efficiency and productivity.
  • Patent Document 1 Korea Patent Laid-Open Publication No. 10-2015-0075275 (published on July 3, 2015 )
  • An aspect of the present disclosure is to provide a cryogenic austenitic high manganese steel in which surface quality is effectively secured by suppressing formation of grooves in a surface, and a manufacturing method therefor.
  • An object of the present disclosure is not limited to the abovementioned contents . Those skilled in the art will have no difficulty in understanding an additional object of the present disclosure from the general contents of the present specification.
  • a cryogenic austenitic high manganese steel having excellent surface quality contains: by wt%, 0.4 to 0.5% of C, 23 to 26% of Mn, 0.03 to 0.5% of Si, 3 to 5% of Cr, 0.05% or less of Al, 0.05% or less of S, 0.5% or less of P, 0.005% or less of B, a balance Fe, and inevitable impurities; and 95 area% or more of austenite as a microstructure, wherein at the time of observing a cross section using an optical microscope, the number of surface flows formed at a depth of 10 ⁇ m or more from a surface among surface flaws observed in a region from the surface to a point of t/8 (here, t refers to a product thickness (mm)) is 0.0001 or less per unit area (mm 2 ).
  • the cryogenic austenitic high manganese steel may further contain 0.7wt% or less of Cu.
  • a yield strength of the cryogenic austenitic high manganese steel may be 400 MPa or more and a Charpy impact toughness of the cryogenic austenitic high manganese steel at -196°C may be 41 J or more.
  • a manufacturing method for a cryogenic austenitic high manganese steel having excellent surface quality includes: reheating a slab in a temperature range of 1000 to 1300°, the slab comprising: by wt%, 0.4 to 0.5% of C, 23 to 26% of Mn, 0.03 to 0.5% of Si, 3 to 5% of Cr, 0.05% or less of Al, 0.05% or less of S, 0.5% or less of P, 0.005% or less of B, a balance Fe, and inevitable impurities; rough-rolling the reheated slab to provide a rough rolled bar; and finish-rolling the rough rolled bar in a temperature range of 750 to 1000°C to provide a hot rolled material, wherein a reheating temperature (T SR ) of the slab and a rolling reduction (R RM ) of the rough rolling are controlled so as to satisfy the following Relational Equation 1, R RM / T SR > 0.15 (In Relational Equation 1, R RM and T SR
  • the slab may further contain 0.7wt% or less of Cu.
  • the finish-rolled hot rolled material may be accelerated-cooled to 600°C or lower at a cooling speed of 10°C/s or more.
  • an austenitic high manganese steel having excellent surface quality while having physical properties particularly suitable for a cryogenic application may be provided.
  • an austenitic high manganese steel material of which productivity and economical efficiency may be secured by securing excellent surface quality without involving a subsequent process such as grinding, and a manufacturing method therefor may be provided.
  • the present disclosure relates to a cryogenic austenitic high manganese steel and a manufacturing method therefor, and exemplary embodiments in the present disclosure will hereinafter be described. Exemplary embodiments in the present disclosure may be modified to have several forms, and it is not to be interpreted that the scope of the present disclosure is limited to exemplary embodiments described below. Exemplary embodiments in the present disclosure are provided in order to further describe the present disclosure in detail to those skilled in the art to which the present disclosure pertains.
  • compositions of a steel according to the present disclosure will be described in more detail.
  • % indicating a content of each element is based on weight.
  • a cryogenic austenitic high manganese steel having excellent surface quality according to an exemplary embodiment in the present disclosure may contain, by wt%, 0.4 to 0.5% of C, 23 to 26% of Mn, 0.03 to 0.5% of Si, 3 to 5% of Cr, 0.05% or less of Al, 0.05% or less of S, 0.5% or less of P, 0.005% or less of B, a balance Fe, and inevitable impurities.
  • the cryogenic austenitic high manganese steel material having excellent surface quality according to an exemplary embodiment in the present disclosure may further contain 0.7wt% or less of Cu.
  • Carbon (C) is an element that is effective in stabilizing austenite in a steel and securing strength by solid solution strengthening. Therefore, in the present disclosure, a lower limit of a content of carbon (C) may be limited to 0.4% in order to secure low-temperature toughness and strength.
  • a preferable lower limit of a content of carbon (C) may be 0.41%, and a more preferable lower limit of the content of carbon (C) may be 0.43%. The reason is that when the content of carbon (C) is less than 0.4%, a yield strength may be decreased, austenite stability may be decreased, such that ferrite or martensite may be formed, and low-temperature toughness may be decreased.
  • an upper limit of the content of carbon (C) may be limited to 0.5%.
  • a preferable upper limit of a content of carbon (C) may be 0.49%, and a more preferable upper limit of the content of carbon (C) may be 0.47%.
  • Manganese (Mn) is an important element that serves to stabilize austenite. Therefore, in the present disclosure, a lower limit of a content of manganese (Mn) may be limited to 23% in order to achieve such an effect. That is, the cryogenic austenitic high manganese steel having excellent surface quality according to an exemplary embodiment in the present disclosure contains 23% or more of manganese (Mn) , and austenite stability may thus be effectively increased. Therefore, formation of ferrite, ⁇ -martensite, and ⁇ '-martensite may be suppressed to effectively secure low-temperature toughness. A more preferable lower limit of the content of manganese (Mn) may be 23.1%.
  • an upper limit of the content of manganese (Mn) may be limited to 26%.
  • a more preferable upper limit of the content of manganese (Mn) may be 25.5%.
  • Silicon (Si) 0.03 to 0.5%
  • Silicon (Si) is a deoxidizing agent like aluminum (Al), and is an element that is indispensably added in a trace amount.
  • Al aluminum
  • an upper limit of a content of silicon (Si) may be limited to 0.5%.
  • a more preferable upper limit of the content of silicon (Si) may be 0.45%.
  • an excessive cost is required in order to reduce the content of silicon (Si) in the steel.
  • a lower limit of the content of silicon (Si) may be limited to 0.03%.
  • a more preferable lower limit of the content of silicon (Si) may be 0.04%.
  • Chromium (Cr) 3 to 5%
  • Chromium (Cr) is an element that contributes to an increase in strength through solid solution strengthening in austenite.
  • chromium (Cr) is an element that has excellent corrosion resistance and thus effectively contributes to prevention of deterioration of surface quality due to high-temperature oxidation. Therefore, in the present disclosure, a lower limit of a content of chromium (Cr) may be limited to 3% in order to achieve such an effect.
  • a preferable lower limit of a content of chromium (Cr) may be 3.1%, and a more preferable lower limit of the content of chromium (Cr) may be 3.3%.
  • an upper limit of the content of chromium (Cr) may be limited to 5%.
  • a preferable upper limit of the content of chromium (Cr) may be 4.5%, and a more preferable upper limit of the content of chromium (Cr) may be 4.0%.
  • Sulfur (S) is not only an impurity element that is inevitably introduced, but is also an element that causes a hot shortness defect due to formation of inclusions. Therefore, in the present disclosure, an upper limit of a content of sulfur (S) may be actively suppressed, and a preferable upper limit of the content of sulfur (S) may be 0.05%.
  • Phosphorus (P) 0.5% or less
  • Phosphorus (P) is not only an impurity element that is inevitably introduced, but is also an element that is easily segregated and an element that causes cracking during casting or deteriorates weldability. Therefore, in the present disclosure, an upper limit of a content of phosphorus (P) may be actively suppressed, and a preferable upper limit of the content of phosphorus (P) may be 0.5%.
  • Boron (B) is an element that contributes to improvement of surface quality by an effect of suppressing an intergranular fracture through strengthening of a grain boundary, but is also an element that deteriorates toughness and weldability due to formation of coarse precipitates, or the like, when it is excessively added. Therefore, in the present disclosure, 0.0)05% or more of boron (B) may be contained in order to achieve surface quality improving effect, but an upper limit of a content of boron (B) may be limited to 0.005% in order to prevent the deterioration of the weldability.
  • Copper (Cu) is an austenite stabilizing element, is an element that stabilizes austenite along with manganese (Mn) and carbon (C) , and is an element that contributes to improvement of low-temperature toughness.
  • copper (Cu) is an element of which a solid solubility in carbide is very low and diffusion in austenite is slow
  • copper (Cu) is an element that is concentrated on an interface between austenite and carbide and surrounds a nuclear of fine carbide to effectively suppress generation and growth of carbide due to additional diffusion of carbon (C) . Therefore, in the present disclosure, a predetermined content of copper (Cu) may be additionally added in order to achieve such an effect.
  • a lower limit of a content of copper (Cu) may be 0.3%, a preferable lower limit of the content of copper (Cu) may be 0.35% , and a more preferable lower limit of the content of copper (Cu) may be 0.4%.
  • an upper limit of the content of copper (Cu) may be limited to 0.7%.
  • a preferable upper limit of the content of copper (Cu) may be 0.65% , and a more preferable upper limit of the content of copper (Cu) may be 0.6%.
  • the cryogenic austenitic high manganese steel having excellent surface quality may contain the balance Fe and other inevitable impurities, in addition to the components described above.
  • unintended impurities may inevitably be mixed from a raw material or the surrounding environment, and thus, these impurities may not be completely excluded. Since these impurities are known to those skilled in the art, all the contents are not specifically mentioned in the present specification.
  • addition of effective components other than the compositions described above is not excluded.
  • the cryogenic austenitic high manganese steel having excellent surface quality contains 95 area% or more of austenite as a microstructure, and at the time of observing a cross section using an optical microscope, the number of surface flows formed at a depth of 10 ⁇ m or more from a surface among surface flaws observed in a region from the surface to a point of t/8 (here, t refers to a product thickness (mm) ) may be 0.0001 or less per unit area (mm 2 ) .
  • an observation region refers to an arbitrary rectangular region formed on a cross section of the steel, and one surface of the observation region may be positioned adjacent to a surface of the steel.
  • a height of the observation region is t/8 (t is a product thickness (mm) )
  • a surface flaw number density may be calculated using the number of surface flaws having a depth of a predetermined level or more among flaws formed in the observation region.
  • cryogenic austenitic high manganese steel having excellent surface quality in the cryogenic austenitic high manganese steel having excellent surface quality according to an exemplary embodiment in the present disclosure, formation of surface flaws on a product surface is actively suppressed through strict process condition control as described below. Therefore, surface quality is effectively secured, such that a subsequent process such as a grinding process or the like may be omitted, and economical efficiency and productivity of a product may thus be effectively secured.
  • cryogenic austenitic high manganese steel having excellent surface quality has a yield strength of 400 MPa or more and a Charpy impact toughness of 41 J or more at -196°C
  • an austenitic high manganese steel particularly appropriate as a material of a fuel tank, a storage tank, a ship membrane, a transport pipe, and the like, for storage and transport of liquefied petroleum gas, liquefied natural gas and the like requiring cryogenic properties may be provided.
  • the cryogenic austenitic high manganese steel having excellent surface quality may be manufactured by reheating a slab having the composition described above in a temperature range of 1000 to 1300°C, rough-rolling the reheated slab to provide a rough rolled bar, and finish-rolling the rough rolled bar in a temperature range of 750 to 1000°C to provide a hot rolled material, wherein a reheating temperature (T SR , °C) of the slab and a rolling reduction (R RM , mm) of the rough rolling are controlled so as to satisfy the following Relational Equation 1: R RM / T SR > 0.15 .
  • a steel composition of the slab corresponds to the steel composition of the austenitic high manganese steel described above, and a description for the steel composition of the slab is thus replaced by the description for the steel composition of the austenitic high manganese steel described above.
  • the slab having the steel composition described above may be uniformly heated in a temperature range of 1000 to 1300°C.
  • a thickness of the slab provided in the reheating of the slab may be about 250 mm, but the scope of the present disclosure is not necessarily limited thereto.
  • a lower limit of a slab reheating temperature may be limited to 1000°C.
  • an upper limit of the slab reheating temperature may be limited to 1300°C.
  • a hot rolling process of rough-rolling the reheated slab to be a rough rolled bar and finish-rolling the rough rolled bar in a temperature range of 750 to 1000°C to provide a hot rolled material may be involved.
  • a finish rolling temperature of hot rolling becomes higher, a deformation resistance decreases, such that the ease of rolling is secured, but as the finish rolling temperature becomes higher, deterioration of surface quality due to grain boundary oxidations is caused.
  • the finish rolling temperature of the present disclosure may be limited to 750 to 1000°C.
  • the austenitic high manganese steel according to the present disclosure contains a large amount of manganese (Mn) having strong oxidizing properties, grain boundary oxidations are inevitably generated even when a temperature of a heating furnace is limited. Even though some of the formed grain boundary oxidations are removed as scales during the reheating of the slab, the remaining grain boundary oxidations grow into cracks during hot rolling to form surface flaws on a surface of a product, such that surface quality of the product is deteriorated.
  • Mn manganese
  • the inventors of the present disclosure came to the conclusion that it is effective to make a structure fine by allowing recrystallization to occur as quickly as possible after heating the slab in order to minimize growth of grain boundary oxidations remaining on a surface of the slab into cracks during hot rolling, through an in-depth study.
  • an increase in a deformation speed is the most effective in order to promote the recrystallization, and the increase in the deformation speed is a factor that may be achieved through an increase in a rolling reduction of rough rolling, but when the rolling reduction excessively increases, separately from minimizing the growth of grain boundary oxidations into cracks, damage to a facility due to an excessive rolling load, or the like, may be problematic.
  • Relational Equation 1 for controlling a rolling load of hot rolling to be a threshold value or less while actively suppressing the formation of the surface flaws of the product through repeated experiments.
  • R RM / T SR > 0.15 (In Relational Equation 1, R RM and T SR refer to a rolling reduction (mm) of rough rolling and a reheating temperature (°C) of the slab, respectively)
  • a rolling reduction of rough rolling with respect to a temperature of a heating furnace is controlled to be in a predetermined range as in the above Relational Equation 1, such that when the temperature of the heating furnace is high, the rolling reduction of the rough rolling may be relatively increased to suppress growth of grain boundary oxidations into surface flaws during hot rolling, and when the temperature of the heating furnace is low, the rolling reduction of the rough rolling may be relatively decreased to decease a rolling load applied to a rolling mill during hot rolling.
  • an optimal slab heating condition and hot rolling condition may be provided.
  • the finish-rolled hot rolled material may be accelerated-cooled to 600°C or lower at a cooling rate of 10°C/s or more. Since the austenitic high manganese steel according to the present disclosure contains 3 to 5% of chromium (Cr) and C, a cooling rate of the hot rolled material is controlled to be 10°C/s or more to effectively prevent a decrease in low-temperature toughness due to carbide precipitation. In addition, in general accelerated-cooling, it is difficult to implement a cooling rate exceeding 100°C/s due to characteristics of a facility. Thus, in the present disclosure, an upper limit of the cooling rate may be limited to 100°C/s.
  • a cooling stop temperature may be limited to 600°C or less.
  • the austenitic high manganese steel manufactured as described above contains 95 area% or more of austenite as a microstructure, and at the time of observing a cross section using an optical microscope, the number of surface flaws formed at a depth of 10 ⁇ m or more from a surface may be 0.0001 or less per unit area (mm 2 ) with respect to a cross-sectional area from the surface to a point of t/8 (here, t refers to a product thickness (mm)), and the austenitic high manganese steel may have a yield strength of 400 MPa or more and a Charpy impact toughness of 41 J or more at -196°C.
  • Slabs having a thickness of 250 mm were manufactured using steels having compositions of Table 1, and specimens were manufactured and prepared under process conditions of Table 2. Each specimen was prepared by performing finish-rolling in a temperature range of 750 to 1000°C, and performing accelerated-cooling to 600°C or lower at a cooling rate of 10°C/s or more. For each specimen, impact absorption energy, a yield strength, and whether or not surface flaws have been formed, were evaluated, and evaluation results were shown together in Table 2 . The impact absorption energy was evaluated at -196°C using a plate-shaped specimen having a notch of 2 mm in accordance with ASTM E23, which is a standard test method.
  • a tensile test was evaluated with a one-way tensile tester by processing a plate-shaped specimen conforming to ASTM E8/E8M, which is a standard test method.
  • a depth and the number of surface flaws were evaluated by cutting a specimen in a thickness direction to prepare the specimen according to ASTM E112, and then measuring a depth of the largest surface flaw in an observation region and the number of surface flaws having a depth of 10 ⁇ m or more per unit area in the observation region using an optical microscope.
  • FIG. 1 is a photograph of a surface of Specimen 1
  • FIG. 2 is a photograph of a surface of Specimen 3. It can be seen as a result of observation with the naked eyes that a large amount of fine surface flaws were formed in Specimen 1, while surface flaws were not formed in Specimen 3, such that excellent surface quality was secured.
  • FIG. 3 is a photograph obtained by cutting Specimen 1 in a thickness direction and then observing a cross section of Specimen 1 with an optical microscope, and it may be confirmed from FIG. 3 that surface flaws were formed on a surface side of Specimen 1 in a direction inclined with respect to a thickness direction of Specimen 1.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
EP19877327.7A 2018-10-25 2019-10-25 Acier inoxydable austénitique cryogénique à haute teneur en manganèse présentant une excellente qualité de surface et procédé de fabrication associé Pending EP3872217A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
KR20180128501 2018-10-25
KR1020190118927A KR102255827B1 (ko) 2018-10-25 2019-09-26 표면품질이 우수한 극저온용 오스테나이트계 고망간 강재 및 그 제조방법
PCT/KR2019/014170 WO2020085851A1 (fr) 2018-10-25 2019-10-25 Acier inoxydable austénitique cryogénique à haute teneur en manganèse présentant une excellente qualité de surface et procédé de fabrication associé

Publications (2)

Publication Number Publication Date
EP3872217A1 true EP3872217A1 (fr) 2021-09-01
EP3872217A4 EP3872217A4 (fr) 2021-09-01

Family

ID=70733248

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19877327.7A Pending EP3872217A4 (fr) 2018-10-25 2019-10-25 Acier inoxydable austénitique cryogénique à haute teneur en manganèse présentant une excellente qualité de surface et procédé de fabrication associé

Country Status (3)

Country Link
EP (1) EP3872217A4 (fr)
KR (1) KR102255827B1 (fr)
CN (1) CN112888804A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114888075A (zh) * 2022-04-13 2022-08-12 大冶特殊钢有限公司 一种钎具用80Mn14Ti钎芯的轧制方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113637908B (zh) * 2021-07-30 2023-05-12 河钢股份有限公司 一种大厚度低温环境用高锰钢板及其生产方法

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5623259A (en) * 1979-08-03 1981-03-05 Sumitomo Metal Ind Ltd Nickel-free high manganese cast steel for low temperature use
JP2978427B2 (ja) * 1995-05-22 1999-11-15 株式会社神戸製鋼所 極低温用高Ｍｎ非磁性鋼及び製造方法
KR20000041265A (ko) * 1998-12-22 2000-07-15 이구택 표면스켑결함과 크랙결함을 동시에 방지하는 미니밀공정에 의한고망간강 열연강판의 제조방법
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
JP6002779B2 (ja) * 2011-12-23 2016-10-05 ポスコＰｏｓｃｏ 非磁性高強度高マンガン鋼板及びその製造方法
KR20150075275A (ko) 2013-12-25 2015-07-03 주식회사 포스코 저온인성이 우수한 고망간 강판 및 그 제조방법
KR101543916B1 (ko) * 2013-12-25 2015-08-11 주식회사 포스코 표면 가공 품질이 우수한 저온용강 및 그 제조 방법
KR101665821B1 (ko) * 2014-12-24 2016-10-13 주식회사 포스코 표면 가공 품질이 우수한 저온용 강판 및 그 제조방법
JP6703608B2 (ja) * 2015-12-22 2020-06-03 ポスコＰｏｓｃｏ 耐水素脆化性に優れたオーステナイト系鋼材
KR101889187B1 (ko) * 2015-12-23 2018-08-16 주식회사 포스코 열간 가공성이 우수한 비자성 강재 및 그 제조방법
WO2017111510A1 (fr) * 2015-12-23 2017-06-29 주식회사 포스코 Matériau d'acier non magnétique ayant une excellente aptitude au façonnage à chaud et son procédé de fabrication
CN106222554A (zh) * 2016-08-23 2016-12-14 南京钢铁股份有限公司 一种经济型超低温用钢及其制备方法
KR101940874B1 (ko) * 2016-12-22 2019-01-21 주식회사 포스코 저온인성 및 항복강도가 우수한 고 망간 강 및 제조 방법
KR101899692B1 (ko) * 2016-12-23 2018-09-17 주식회사 포스코 극저온용 오스테나이트계 고 망간 강 및 제조방법
CN107177786B (zh) * 2017-05-19 2018-12-21 东北大学 一种lng储罐用高锰中厚板的设计及其制造方法
CN108570541B (zh) * 2018-05-14 2020-07-10 东北大学 一种lng储罐用高锰中厚板的高温热处理方法

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114888075A (zh) * 2022-04-13 2022-08-12 大冶特殊钢有限公司 一种钎具用80Mn14Ti钎芯的轧制方法

Also Published As

Publication number Publication date
KR102255827B1 (ko) 2021-05-26
CN112888804A (zh) 2021-06-01
KR20200047320A (ko) 2020-05-07
EP3872217A4 (fr) 2021-09-01

Similar Documents

Publication Publication Date Title
EP2617850B1 (fr) Tôle en acier laminée à chaud à haute résistance présentant une excellente ténacité et son procédé de fabrication
EP3135787B1 (fr) Tôle d'acier et son procédé de fabrication
EP3246426B1 (fr) Procédé de fabrication d'une tôle d'acier épaisse de haute ténacité et de haute résistance
JP7147960B2 (ja) 鋼板およびその製造方法
EP3202943A1 (fr) Tube d'acier haute résistance sans soudure pour puits de pétrole, et procédé de production de tube d'acier haute résistance sans soudure pour puits de pétrole
EP3722448B1 (fr) Acier riche en mn, et procédé de fabrication de celui-ci
WO2018104984A1 (fr) TÔLE D'ACIER À TENEUR ÉLEVÉE EN Mn ET SON PROCÉDÉ DE PRODUCTION
JP7063364B2 (ja) 高Ｍｎ鋼
CN112739843B (zh) 具有优异的冲击韧性的热轧未退火铁素体不锈钢板及其制造方法
KR102389019B1 (ko) 항복강도가 우수한 오스테나이트계 고망간 강재
EP3872217A1 (fr) Acier inoxydable austénitique cryogénique à haute teneur en manganèse présentant une excellente qualité de surface et procédé de fabrication associé
EP3831973A1 (fr) Acier à haute teneur en manganèse et son procédé de production
EP3733905A1 (fr) Matériau d'acier structural à haute résistance ayant d'excellentes caractéristiques d'inhibition de propagation des fissures de fatigue et son procédé de fabrication
JP5428999B2 (ja) Ｌｐｇ・アンモニア混載用鋼材の製造方法
KR102255825B1 (ko) 형상이 우수한 극저온용 오스테나이트계 고망간 강재 및 그 제조방법
EP3872213A1 (fr) Acier austénitique à haute teneur en manganèse pour applications cryogéniques ayant une excellente qualité de surface et une excellente résistance à la fissuration par corrosion sous contrainte, et son procédé de fabrication
KR102387364B1 (ko) 고Mn강 및 그의 제조 방법
JP7323088B1 (ja) 鋼板およびその製造方法
JP7323091B1 (ja) 鋼板およびその製造方法
KR102290103B1 (ko) 스케일 박리성이 우수한 극저온용 오스테나이트계 고망간 강재 및 그 제조방법
EP3859044A1 (fr) Tôle d'acier laminée à chaud présentant une excellente résistance aux chocs à basse température, et procédé de fabrication associé
WO2023162507A1 (fr) Tôle en acier, et procédé de fabrication de celle-ci
WO2023162522A1 (fr) Tôle en acier, et procédé de fabrication de celle-ci
CN115279933A (zh) 厚钢板及其制造方法
WO2023166934A1 (fr) Tôle en acier, et procédé de fabrication de celle-ci

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20210518

A4 Supplementary search report drawn up and despatched

Effective date: 20210628

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
RAP3 Party data changed (applicant data changed or rights of an application transferred)

Owner name: POSCO HOLDINGS INC.

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: POSCO CO., LTD