WO2010109778A1 - Tôle d'acier au carbone présentant d'excellentes propriétés de carburation, et procédé de production associé - Google Patents

Tôle d'acier au carbone présentant d'excellentes propriétés de carburation, et procédé de production associé Download PDF

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WO2010109778A1
WO2010109778A1 PCT/JP2010/001456 JP2010001456W WO2010109778A1 WO 2010109778 A1 WO2010109778 A1 WO 2010109778A1 JP 2010001456 W JP2010001456 W JP 2010001456W WO 2010109778 A1 WO2010109778 A1 WO 2010109778A1
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mass
annealing
steel sheet
cold rolling
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PCT/JP2010/001456
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Japanese (ja)
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阿部雅之
竹田健悟
矢頭久斉
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新日本製鐵株式会社
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Priority to CN201080002531.4A priority Critical patent/CN102149839B/zh
Priority to KR1020117005139A priority patent/KR101122840B1/ko
Priority to JP2010529172A priority patent/JP4659142B2/ja
Priority to US12/998,035 priority patent/US20120006451A1/en
Priority to CA2736374A priority patent/CA2736374A1/fr
Publication of WO2010109778A1 publication Critical patent/WO2010109778A1/fr

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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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C21D1/06—Surface hardening
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
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    • 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
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    • 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
    • C21D8/0268—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment between cold rolling steps
    • 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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0426—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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0436—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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
    • C21D8/0463—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing 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
    • 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
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
    • C21D8/0468—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment between cold rolling steps
    • 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
    • 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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/561—Continuous furnaces for strip or wire with a controlled atmosphere or vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • 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
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces

Definitions

  • the present invention relates to a carbon steel sheet having excellent carburizing and hardenability and a method for producing the same.
  • automotive parts and industrial machine parts such as chain parts, gear parts, and clutch parts are manufactured by hardening the surface by heat treatment such as quenching after molding.
  • the material is required to satisfy not only processability that can withstand complicated processing when processing into parts, but also hardenability for surface hardening.
  • the hardenability and workability of the material are contradictory properties from the viewpoint of material design.
  • softening the material is effective for improving the workability, but many elements added to increase the hardenability increase the hardness of the steel sheet and sacrifice the workability.
  • Patent Document 1 discloses annealing in a hydrogen atmosphere or Ar atmosphere in which the nitrogen content is suppressed to 10% by volume or less. I can't find anything. Moreover, the technique which considered the carburizing process by the low carbon potential which is made into object by this invention is not disclosed.
  • the present invention has an object to provide a B-added steel sheet that has excellent hardenability even under carburizing conditions with a low carbon potential and that has workability, and to optimize its manufacturing method.
  • the present invention employs the following means in order to solve the above-described problems.
  • C 0.20 mass% or more, 0.45 mass% or less, Si: 0.05 mass% or more, 0.8 mass% or less, Mn: 0.85 mass %: 2.0 mass% or less, P: 0.001 mass% or more, 0.04 mass% or less, S: 0.0001 mass% or more, 0.006 mass% or less, Al: 0.01 mass% or more 0.1 mass% or less, Ti: 0.005 mass% or more, 0.3 mass% or less, B: 0.0005 mass% or more, 0.01 mass% or less, and N: 0.001 mass% or more, It contains 0.01% by mass or less of components, the balance is Fe and inevitable impurities, and the K value obtained by 3C + Mn + 0.5Si is 2.0 or more; the surface hardness is 77 or less on the Rockwell hardness B scale The average content of N in the region from the surface layer to a depth of 100 ⁇ m is 10
  • the carbon steel plate described in (1) above has Nb: 0.01% by mass or more and 0.5% by mass or less, V: 0.01% by mass or more, 0.5% by mass or less, Ta: 0.00%. 01% by mass or more, 0.5% by mass or less, W: 0.01% by mass or more, 0.5% by mass or less, Sn: 0.003% by mass or more, 0.03% by mass or less, Sb: 0.003% by mass %, 0.03% by mass or less, and As: 0.003% by mass or more and 0.03% by mass or less, may further contain one or more components.
  • a second aspect of the present invention is a heating step in which the slab is heated at 1200 ° C. or lower; a hot rolling step in which the slab is hot-rolled at a finish rolling temperature of 800 ° C. or higher and 940 ° C. or lower to obtain a steel plate. And a first cooling step of cooling the steel plate at a cooling rate of 20 ° C./second or higher until the steel plate reaches 650 ° C. or lower; following the first cooling step, the steel plate at a cooling rate of 20 ° C./second or lower. A second cooling step for cooling the steel plate; a scraping step for scraping the steel plate at 650 ° C. or lower and 400 ° C.
  • a first annealing step in which annealing is performed at a temperature of 660 ° C. or more for 10 hours or more in an atmosphere in which a dew point of ⁇ 20 ° C. or less and a dew point of 400 ° C. or more is ⁇ 40 ° C. or less is provided.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a first cold rolling process for cold rolling the steel sheet at a rolling rate of 5% or more and 60% or less after the pickling process is further performed. You may prepare.
  • a second cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% to 60% after the first annealing process. And after the second cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a second annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a third cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% or more and 60% or less after the second annealing process. And after the third cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a third annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a third cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% to 60% after the second annealing process. And after the third cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a third annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a second cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% to 60% after the first annealing process. And after the second cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a second annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a third cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% or more and 60% or less after the second annealing process. And after the third cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a third annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a third cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% to 60% after the second annealing process. And after the third cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a third annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • the first cold rolling step of cold rolling the steel plate at a rolling rate of 5% to 60% after the pickling step is further performed. You may prepare.
  • a second cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% to 60% after the first annealing process. And after the second cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a second annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a third cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% to 60% after the second annealing process. And after the third cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a third annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a third cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% or more and 60% or less after the second annealing process. And after the third cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a third annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a second cold rolling process in which the steel sheet is cold-rolled at a rolling rate of 5% to 60% after the first annealing process. And after the second cold rolling step, the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower, the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower, and the temperature is 660 ° C. or higher. And a second annealing step for annealing the steel sheet.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • a third cold rolling step of cold rolling the steel plate at a rolling rate of 5% to 60% after the second annealing step is performed.
  • the dew point of 95% or more of hydrogen and up to 400 ° C. is ⁇ 20 ° C. or lower
  • the dew point of 400 ° C. or higher is ⁇ 40 ° C. or lower
  • the temperature is 660 ° C. or higher.
  • a third annealing step for annealing the steel sheet is performed in the method for producing a carbon steel plate according to (25).
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is in the range of Ac1 to Ac1 + 50 ° C.
  • the cooling rate up to 30 ° C may be set to 5 ° C / hour or less.
  • C 0.20% by mass or more and 0.45% by mass or less
  • Si 0.05% by mass or more, 0.8% by mass or less
  • Mn 0.85% by mass %: 2.0 mass% or less
  • P 0.001 mass% or more, 0.04 mass% or less
  • S 0.0001 mass% or more, 0.006 mass% or less
  • Al 0.01 mass% or more 0.1 mass% or less
  • Ti 0.005 mass% or more, 0.3 mass% or less
  • B 0.0005 mass% or more, 0.01 mass% or less
  • N 0.001 mass% or more
  • Cr 0.01% by mass or more, 2.0% by mass or less
  • Ni 0.01% by mass or more, 1.0% by mass or less
  • Cu 0.005% by mass %, 0.5% by mass or less
  • Mo 0.01% by mass or more, 1.0% by mass or less of one or more components.
  • the balance has Fe and inevitable impurities; the K ′ value obtained by 3C + Mn + 0.5Si + Cr + Ni + Mo + Cu is 2.0 or more; the surface hardness is 77 or less on the Rockwell hardness B scale; the depth from the surface layer
  • the carbon steel sheet has an average N content of 100 ppm or less in a 100 ⁇ m region. This carbon steel sheet is carburized in a carburizing atmosphere having a carbon potential of 0.6 or less.
  • the carbon steel plate described in (31) above has Nb: 0.01% by mass or more and 0.5% by mass or less, V: 0.01% by mass or more, 0.5% by mass or less, Ta: 0.00%. 01% by mass or more, 0.5% by mass or less, W: 0.01% by mass or more, 0.5% by mass or less, Sn: 0.003% by mass or more, 0.03% by mass or less, Sb: 0.003% by mass %, 0.03% by mass or less, and As: 0.003% by mass or more, 0.03% by mass or less, may further contain one or more components.
  • the carbon steel plate according to (31) or (32) above is a steel plate obtained by hot-rolling the slab at a finish rolling temperature of 800 ° C. or higher and 940 ° C. or lower; A first cooling step for cooling the steel plate at a cooling rate of 20 ° C./second or more until the steel plate reaches 650 ° C. or lower; a cooling rate of 20 ° C. following the first cooling step; A second cooling step for cooling the steel plate at a speed of less than / second; a scraping step for scraping the steel plate at 650 ° C. or lower and 400 ° C. or higher; a pickling step for pickling the steel plate; And a first annealing step of annealing at a temperature of 660 ° C.
  • the K value or K ′ value is 2.0 or more, and the surface layer average N amount is specified to be 100 ppm or less, so that it is high even under carburizing conditions with low carbon potential. Hardenability can be exhibited, and a B-added carbon steel plate having high workability can be obtained.
  • the effect of stabilizing the precipitates and improving the toughness, and the effect of suppressing the component fluctuation of the steel sheet surface layer part can be obtained.
  • the carbon steel plate excellent in workability and the carburizing property after a process can be manufactured stably. According to the methods described in the above (4) to (30), the workability and softening of the carbon steel sheet can be further improved.
  • the present invention not only has an excellent carburizing and quenching property that prevents generation of an abnormal layer due to poor hardenability during carburization of B-added steel, but also a steel material that is excellent in workability to parts and the like. It can be manufactured.
  • the inventors varied the composition of the B-added steel sheet and the manufacturing conditions during the manufacturing process, conducted a hardness change and structural investigation of the surface layer during carburizing and quenching, and affected the hardenability of the surface layer.
  • the relationship between tissues and ingredients was clarified.
  • a structure softened from martensite such as pearlite, sorbite, and troostite, which are not martensite, may be generated in the surface layer portion, and is often found particularly in the extreme surface layer portion of about 100 ⁇ m from the surface.
  • FIG. 1 shows the occurrence of an abnormal layer for a material that has been carburized and quenched with a 0.22% C-based carbon potential at 0.3.
  • the abnormal layer is greatly related to the nitrogen (N) content (surface layer average N amount) in the steel sheet surface layer part from the steel sheet surface to the plate thickness direction 100 ⁇ m and the K value (or K ′ value) obtained from the steel sheet component. Turned out to be.
  • the surface layer average N amount is a value obtained by analyzing the content of nitrogen (N) in the swarf of the steel plate obtained by plane-cutting 100 ⁇ m in the thickness direction from the surface of the steel plate before carburizing and quenching. is there.
  • K value 3C + Mn + 0.5Si (1)
  • C, Mn, and Si show content (mass%) of each element.
  • K ′ value 3C + Mn + 0.5Si + Cr + Ni + Mo + Cu (2)
  • C, Mn, Si, Cr, Ni, Mo, and Cu indicate the content (% by mass) of each element.
  • K ′ value the K element shown here as the amount of alloy elements. did it.
  • the higher this K value (K ′ value) the better the hardenability is ensured.
  • the upper limit of the K value (K ′ when Cr, Ni, Mo, Cu is included) is not particularly defined, but if it exceeds 3.6, the hardenability is too high and the above-mentioned defects such as cracking may occur. Therefore, 3.6 or less is desirable.
  • the surface hardness of the steel sheet is specified to be 77 or less on the Rockwell hardness B scale (HRB).
  • HRB Rockwell hardness B scale
  • a machining experiment simulating tooth profile machining was performed as an evaluation of processability, and the presence or absence of cracks in a portion subjected to shear deformation of the root portion of the tooth mold was investigated.
  • a steel material having a thickness of 3 mm was manufactured as a test material by using a steel material having a 0.22% C-based component as the steel material and changing the hot rolling, cold rolling, and annealing conditions.
  • the shape of the tooth profile was a rack-shaped mold made with a module of 1.5 mm defined in JIS-B1703, pressed 2 mm against a steel plate with a thickness of 3 mm, and evaluated for the presence or absence of cracks in the tooth forming profile.
  • the lower limit of the K value (K ′ value) is defined from the viewpoint of ensuring hardenability.
  • K the harder it is, and it is advantageous for the hardness at the time of quenching.
  • workability is inferior, problems such as cracking occur at the time of processing. Therefore, it is necessary to carry out the manufacturing method defined in the present invention and to soften the steel sheet while controlling the atmosphere during annealing.
  • C A basic element necessary to obtain the strength of the steel sheet. If the carbon content is less than 0.20%, the required strength as a product cannot be obtained, and the hardenability of the central part of the component is also lowered, and desired characteristics cannot be obtained. However, if a large amount of C exceeding 0.45% is contained, it is difficult to ensure toughness and formability after heat treatment, so 0.20 to 0.45% by mass (hereinafter, unless otherwise specified, the content is The C content was determined in the range of (in mass%). A more preferable range is 0.20 to 0.40%.
  • Si Used as a deoxidizer for steel, effective from the viewpoint of hardenability, and needs to contain 0.05% or more of Si.
  • the upper limit is set to 0.80% because surface properties are deteriorated due to scale wrinkles and the like during hot rolling as the Si content increases.
  • a more preferred range is 0.05 to 0.50%.
  • Mn Used as a deoxidizer and effective from the viewpoint of hardenability. In the present invention, it is necessary to add 0.85% or more from the viewpoint of ensuring hardenability in carburization performed at low Cp, but if Mn is too high, impact characteristics due to structural changes after quenching and tempering due to segregation.
  • the upper limit is specified to be 2.0%. A more preferred range is 0.90 to 1.80%.
  • the steel according to the present invention is a harmful element from the viewpoint of toughness and workability, and the lower the P content, the better.
  • the upper limit is specified to 0.04%. Further, the lower limit is desirable, but the lower limit is specified to be 0.001% because reducing the cost from 0.001% greatly increases the industrial cost. A more preferred range is 0.003 to 0.025%.
  • S promotes the formation of non-metallic inclusions in the steel, and deteriorates the formability and toughness after heat treatment. For this reason, the lower the S content, the better, and the upper limit is defined as 0.006%. Although the lower limit is desirable, the lower limit is specified to be 0.0001% because a reduction from 0.0001% greatly increases the industrial cost. A more preferred range is 0.0001 to 0.003%.
  • Al Used as a deoxidizer for steel. For this purpose, 0.01% or more of Al is necessary. However, even if Al exceeding 0.10% is added, the effect is saturated and surface defects are likely to occur. Al is also effective for fixing N, and promotes nitrogen absorption during the production of steel sheets. However, if its content exceeds 0.10%, the Al nitride becomes stable, which inhibits grain growth during the carburizing heat treatment and causes hardenability to deteriorate. Therefore, the Al content is specified in the range of 0.01 to 0.10%. A more preferred range is 0.01 to 0.06%.
  • Ti Effective for deoxidation of steel and fixation of N, 0.005% or more of addition is necessary in relation to the amount of N. However, even if adding Ti exceeding 0.30%, the effect is saturated and the cost also increases. Furthermore, since the amount of precipitates due to nitrogen absorption during the manufacturing process increases, grain growth during carburization is hindered and the hardenability is deteriorated. Therefore, the range of Ti is specified to be 0.01 to 0.30%. A more preferred range is 0.01 to 0.10%.
  • B An effective element that improves the hardenability of steel, and the effect is seen from a very small amount. In order to obtain the effect of improving hardenability, 0.0005% or more must be added. However, if a large amount of B exceeding 0.01% is contained, the castability deteriorates and cracks occur during slab casting. Furthermore, adverse effects such as generation of B-based compounds in the steel and a reduction in toughness are observed. Therefore, the B content is specified to be 0.0005% to 0.01%. A more preferred range is 0.0005 to 0.005%.
  • N Combines with B to form a nitride, which deteriorates the hardenability improvement effect of B.
  • the N content is preferably as low as possible, but reducing it to less than 0.001% causes an increase in cost.
  • the content exceeds 0.01% as the average composition of steel, a large amount of elements for fixing N such as AL and Ti is required, and precipitates such as AlN and TiN cause grain growth during carburization. It inhibits and reduces hardenability, and not only causes abnormal layers, but also deteriorates mechanical properties such as toughness. Therefore, the upper limit of N content is specified as 0.01%. A more preferred range is 0.001 to 0.006%.
  • N easily penetrates into the steel during the manufacturing process, and enters from the atmosphere during hot rolling and annealing, so it is easy to concentrate especially in the surface layer part, and its influence is suppressed to deteriorate the hardenability of the part surface layer part. Necessary to prevent. If the nitrogen intrusion from the atmosphere during heating or annealing exceeds 100 ppm, the amount of nitrides deposited during cutting or annealing increases, grain growth during heating before quenching is delayed, and hardenability deteriorates. Therefore, it is particularly important that the N content (surface layer average N amount) in the surface layer portion (in the range of 100 ⁇ m in the thickness direction from the surface) is regulated to 100 ppm or less. More preferably, the N content in the surface layer is 70 ppm or less.
  • Cr It is an effective element that can be added from the viewpoint of hardenability of steel, and the effect becomes remarkable at 0.01% or more, but even if added over 2%, the effect is saturated, and the cost is also reduced. Get higher. Therefore, the content is specified to be 0.01 to 2.0%. A more preferred range is 0.05 to 0.50%.
  • Ni It is an effective element from the viewpoint of improving the hardenability and toughness of steel. Addition at 0.01% or more is effective, but if it exceeds 1%, it only causes an increase in cost. The content is specified to be 0.02 to 1.0% because it does not change much. A more preferred range is 0.05 to 0.50%.
  • Cu It is an effective element from the viewpoint of improving the hardenability and toughness of steel. Addition at 0.01% or more is effective, but adding more than 0.5% only causes an increase in cost. Since the effect does not change much, the content is specified to be 0.005 to 0.5%. A more preferred range is 0.02 to 0.35%.
  • Mo An effective element for improving the hardenability of steel, and an element effective for increasing the softening resistance by tempering. In order to obtain the effect, addition of 0.01% or more is necessary. However, even if the content exceeds 1.0%, the effect is saturated and the cost increases, so the content is defined as 0.01 to 1.0%. A more preferred range is 0.01 to 0.40%.
  • Nb Forms carbonitride and is effective for stabilizing precipitates and improving toughness at 0.01% or more, but adding more than 0.5% causes an increase in cost. Since this leads to a decrease in hardenability, the range is specified as 0.01 to 0.5%. A more preferred range is 0.01 to 0.20%.
  • V Carbonitride is formed in the same way as Nb, and it is effective at 0.01% or more for stabilizing precipitates and improving toughness. However, adding more than 0.5% only increases the cost. The effect does not change so much and leads to a decrease in hardenability due to carbide formation. Therefore, the range is specified as 0.01 to 0.5%. A more preferred range is 0.01 to 0.20%.
  • Ta Nb
  • V forms carbonitride and is effective in stabilizing precipitates and improving toughness at 0.01% or more, but adding more than 0.5% causes an increase in cost. As a result, the effect does not change much and leads to a decrease in hardenability due to carbide formation. Therefore, the range is specified as 0.01 to 0.5%. A more preferred range is 0.01 to 0.30%.
  • W Carbonitride is formed in the same way as Nb, V, and Ta, and it is effective at 0.01% or more to stabilize precipitates and improve toughness. However, even if added over 0.5%, the cost increases. However, the effect is not much changed, and the hardenability is reduced due to the formation of carbides. Therefore, the range is specified as 0.01 to 0.5%. A more preferred range is 0.01 to 0.20%.
  • Sn, Sb, and As may be added in a required amount.
  • Sn, Sb, As: 0.003-0.03% each Sn, Sb, and As are elements that have a high tendency to segregate at the interface, the surface, and the like, and have a function of suppressing surface layer reactions during production processes such as nitrogen absorption and decarburization. By adding it, even when the steel material is exposed to a high temperature atmosphere during heating or annealing in the hot rolling process, the reaction of elements such as nitrogen and carbon that tend to fluctuate components can be suppressed, and significant component fluctuations can be prevented. is there. Therefore, it may be added as necessary.
  • the content of oxygen (O) is not specified, but when the oxide is agglomerated and coarsened, the ductility is lowered, so the oxygen content is preferably 0.025% or less. . Less oxygen is preferred, but it is technically difficult to make it less than 0.0001%, so 0.0001% or more is preferred.
  • the carbon steel sheet of the present invention may contain impurities inevitably mixed in the manufacturing process in addition to the above elements, but it is preferable that impurities are not mixed as much as possible.
  • Hot rolling is important in the present invention considered through consistent optimization with the steel material components and the subsequent annealing process, and suppresses component fluctuations in the surface layer portion of the steel sheet, that is, N intrusion and decarburization to the surface layer portion as much as possible. This is very important. Therefore, heating is set to 1200 ° C. or less without applying high-temperature heating exceeding 1200 ° C., which is normally used (S1). At this time, as the soaking time becomes longer, more nitrogen penetrates into the surface layer portion, which affects the quenching characteristics of the product. Therefore, it is important that the heating time is not long. Specifically, it is desirable to heat so that the retention time may be 60 minutes at 1200 ° C. and 90 minutes at 1100 ° C.
  • finish rolling temperature 800 ° C. or higher and 940 ° C. or lower (S2). If the finish rolling temperature is lower than 800 ° C., defects due to seizure occur frequently. If the finish rolling temperature is higher than 940 ° C., the frequency of occurrence of defects due to scale increases, resulting in a decrease in product yield and an increase in cost.
  • cooling to 650 ° C. or lower is performed at a cooling rate of 20 ° C./second or more (S3, first cooling). If the cooling to 650 ° C. after the end of rolling is made slower than 20 ° C./second, the structure variation called pearlite band accompanying segregation occurs, which leads to deterioration of workability. Therefore, after the end of rolling, the cooling rate is controlled to a cooling rate of 20 ° C./second or less up to 650 ° C. or less, and then the uniform pearlite transformation, barlite + bainite structure, bainite structure, etc. up to the take-off temperature, Slow cooling at 20 ° C./second or less is performed (S4, second cooling).
  • the coiling temperature can be systematically uniform, so that the systematic fluctuation in the coil can be reduced by winding at a temperature of 650 ° C. or lower and 400 ° C. or higher (S5).
  • the hot-rolled steel sheet manufactured by the above process is pickled (S6). After pickling, annealing and cold rolling are carried out according to the product plate thickness and the required softening level, and the following matters are important as manufacturing conditions at that time.
  • the steel sheet according to the present invention has a high carbon content, so that the characteristics cannot be obtained by a continuous annealing process used in so-called mild steel sheets.
  • a process of annealing a coil as it is called batch annealing or box annealing is applied (S7, first annealing).
  • the annealing atmosphere was an atmosphere mainly composed of hydrogen, and the hydrogen concentration was 95% or more.
  • the inside of the annealing furnace is temporarily replaced with nitrogen at room temperature to form a nitrogen atmosphere and then replaced with hydrogen.
  • the dew point is -20 ° C or less, and the temperature is 400 ° C or more and the holding time (the holding time depends on the material, but for the softening of the steel plate according to the present invention It is desirable to maintain the temperature at 660 ° C. or more for 10 hours or more.) It is important from the viewpoint of preventing fluctuations in the surface layer component that the dew point is ⁇ 40 ° C. or less. Decarburization occurs, and an abnormal layer with poor quenching is generated when carburizing at a low carbon potential. By completing this series of steps (hot rolling + heat treatment), a steel sheet according to the present invention having excellent workability and excellent carburizing and quenching properties in carburizing treatment after processing can be obtained.
  • annealing is performed in a temperature range from Ac1 point to Ac1 + 50 ° C. and the cooling rate after annealing is 5 ° C./hour or less to Ac1-30 ° C. or less.
  • generated by Ac1 or more tends to coarsen the ferrite phase produced
  • the phase ratio of the austenite phase becomes too high in the composition of the steel of the present invention, and partly pearlite is generated during cooling, so that the temperature of high temperature annealing in the present invention is It is preferable that it is Ac1 + 50 degrees C or less. Further, in the steel of the present invention, the effect is saturated even if it is slowly cooled to Ac1-30 ° C. or lower, and the cost increases due to the prolonged annealing time. Therefore, the end point temperature of the slow cooling is up to the above Ac1-30 ° C. It is preferable that Ac1 here indicates the temperature at which the austenite phase appears in the temperature raising process.
  • a sample is taken from a hot-rolled steel sheet, and the expansion curve when the temperature is raised at 0.3 ° C./s with a formaster tester is shown.
  • the A1 transformation point was determined by measurement.
  • cold rolling process is used to finish the product thickness with high accuracy and to efficiently soften in combination with annealing. Therefore, in the series of steps described above, after hot rolling and scraping (S5), pickling (S6), cold rolling (S6-2, first cold rolling) may be performed. .
  • cold rolling with a rolling rate of 5% or more promotes spheroidization of carbides, recrystallization without nucleation, and relatively large grain size upon completion of recrystallization, which tends to cause coarsening due to grain growth, and promotes softening. To do.
  • the upper limit is not particularly defined, but if rolling is performed at a rolling rate exceeding 60%, the uniformity of the metal structure of the steel sheet by cold rolling further increases, but the higher the cold rolling rate, the finer the recrystallized grains during annealing. Therefore, since it is necessary to increase the annealing time for softening, the cold rolling rate can be determined from the viewpoint of cost and product homogenization.
  • the steel sheet is again subjected to cold rolling (S7-2, second cold rolling) with a reduction rate of 5% or more, and then in an atmosphere containing 95% or more of hydrogen.
  • Annealing may be performed (S7-3, second annealing).
  • the steel sheet is subjected to cold rolling (S7-4, third cold rolling) with a rolling reduction of 5% or more
  • annealing S7-5, third annealing
  • manufacturing method it is also possible to implement the above-mentioned annealing process more than 3 degree
  • the carbon steel sheet according to an embodiment of the present invention can be restated as follows, that is, by mass, C: 0.20 to 0.45%, Si: 0.05 to 0.8%, Mn: 0 .85 to 2.0%, P: 0.001 to 0.04%, S: 0.0001 to 0.006%, Al: 0.01 to 0.1%, Ti: 0.005 to 0.3 %, B: 0.0005 to 0.01%, N: 0.001 to 0.01%, the balance is Fe and inevitable impurities, and the value represented by 3C + Mn + 0.5Si + Cr + Ni + Mo + Cu is 2.0 or more
  • the steel plate surface hardness is 77 or less on the Rockwell hardness B scale (HRB), the average nitrogen (N) content from the surface layer to 100 ⁇ m is 100 ppm or less, and the carbon potential (Cp) is 0.6 or less.
  • Carburizing and quenching used in a mild carburizing atmosphere It is a carbon steel plate with excellent properties.
  • C, Mn, Si, Cr, N, Mo, and Cu indicate the content (% by mass) of each element, and are treated as zero when not included.
  • the above-mentioned carbon steel sheet is further mass%, Cr: 0.01 to 2.0%, Ni: 0.01 to 1.0%, Cu: 0.005 to 0.5%, Mo: 0.01 to One or more of 1.0% may be contained, and the value represented by 3C + Mn + 0.5Si + Cr + Ni + Mo + Cu may be 2.0 or more.
  • the above-mentioned carbon steel sheet is further mass%, Nb: 0.01 to 0.5%, V: 0.01 to 0.5%, Ta: 0.01 to 0.5%, W: 0.01 to You may contain 1 type, or 2 or more types of 0.5%.
  • the carbon steel sheet described above may further contain one type of Sn: 0.003-0.03%, Sb: 0.003-0.03%, and As: 0.003-0.03% by mass%. You may contain 2 or more types.
  • the finish rolling temperature of hot rolling is set to 800 ° C. or more and 940 ° C. or less, and the cooling rate is 20 ° C./second to 650 ° C. after finishing rolling.
  • a dew point of 95% or higher hydrogen and up to 400 ° C. May be produced by annealing at a temperature of 660 ° C. or more for 10 hours or more in an atmosphere having a dew point of ⁇ 20 ° C. or less and a dew point of ⁇ 40 ° C. or less at ⁇ 40 ° C. or less.
  • the annealing may be performed after cold rolling at a rolling rate of 5% to 60%.
  • the dew point of hydrogen is 95% or more and up to 400 ° C is -20 ° C or less, and the dew point of 400 ° C or more is -40 ° C or less.
  • annealing may be performed again at a temperature of 660 ° C. or higher.
  • cold rolling at a rolling rate of 5% or more and 60% or less is performed, the dew point of hydrogen is 95% or more and up to 400 ° C is -20 ° C or less, and the dew point of 400 ° C or more is -40 ° C or less. May be annealed at a temperature of 660 ° C.
  • the atmosphere is set to 95% or more of hydrogen and the annealing temperature is annealed in the range of Ac1 to Ac1 + 50 ° C., and the cooling rate after annealing is set to 5 to 1-30 ° C. You may cool slowly below °C / hour.
  • the surface hardness of the obtained steel sheet was measured with the Rockwell hardness B scale (HRB), and the surface layer average N amount was obtained by planing 100 ⁇ m in the thickness direction from the surface of the steel sheet before carburizing and quenching.
  • the content of nitrogen (N) in the swarf of the steel plate was analyzed. Thereafter, the carved sample was carburized and quenched, and the presence or absence of an abnormal layer on the surface was examined.
  • the carburizing treatment was performed by a gas carburizing method, and the carbon potential was measured by a CO2 amount control method using an infrared gas analyzer. No. in Table 7 to Table 12 The numerical part of the column indicates the No. in Table 1 to Table 6. It was made to understand under what conditions the material with which component was carried out.
  • the surface hardness HRB Rockwell hardness B scale
  • the surface hardness HRB Rockwell hardness B scale
  • Tables 7 to 12 From the tooth profile processing test results (Tables 7 to 12), if the HRB is 77 or less, cracks will occur. Confirmed that it does not occur. That is, it was confirmed that the steel sheet according to the present invention is excellent in workability.
  • the steel sheet according to the present invention exhibits sufficient performance even at a low carbon potential (CP ⁇ 0.6), and not only is excellent in carburization but also in workability. It was confirmed to be excellent.
  • this steel material can be applied not only to automobile parts and various industrial machine parts, but also to a wide range of tools and blades, it is needless to say that the field of application is wide, used throughout the industry, and industrially valuable. Yes.

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Abstract

La présente invention concerne une tôle d'acier au carbone contenant pas moins de 0,20 % en masse mais pas plus de 0,45 % en masse de C, pas moins de 0,05 % en masse mais pas plus de 0,8 % en masse de Si, pas moins de 0,85 % en masse mais pas plus de 2,0 % en masse de Mn, pas moins de 0,001 % en masse mais pas plus de 0,04 % en masse de P, pas moins de 0,0001 % en masse mais pas plus de 0,006 % en masse de S, pas moins de 0,01 % en masse mais pas plus de 0,1 % en masse de Al, pas moins de 0,005 % en masse mais pas plus de 0,3 % en masse de Ti, pas moins de 0,0005 % en masse mais pas plus de 0,01 % en masse de B, et pas moins de 0,001 % en masse mais pas plus de 0,01 % en masse de N. La tôle d'acier au carbone présente une valeur K, qui est exprimée par 3C + Mn + 0,5Si, non inférieure à 2,0, une dureté de surface, à savoir une dureté Rockwell, non supérieure à 77 sur l'échelle B, et une teneur moyenne en N non supérieure à 100 ppm dans la région allant de la surface à une profondeur de 100 μm. La tôle d'acier au carbone est carburée dans une atmosphère de carburation ayant un potentiel de carbone non supérieur à 0,6.
PCT/JP2010/001456 2009-03-27 2010-03-03 Tôle d'acier au carbone présentant d'excellentes propriétés de carburation, et procédé de production associé WO2010109778A1 (fr)

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CN201080002531.4A CN102149839B (zh) 2009-03-27 2010-03-03 渗碳淬火性优异的碳钢板及其制造方法
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JP2010529172A JP4659142B2 (ja) 2009-03-27 2010-03-03 浸炭焼入れ性の優れた炭素鋼板およびその製造方法
US12/998,035 US20120006451A1 (en) 2009-03-27 2010-03-03 Carbon steel sheet having excellent carburization properties, and method for producing same
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010255066A (ja) * 2009-04-28 2010-11-11 Jfe Steel Corp 高炭素熱延鋼板およびその製造方法
WO2012056785A1 (fr) * 2010-10-27 2012-05-03 新日本製鐵株式会社 Acier pour durcissement de surface destiné à une utilisation structurale d'une machine, et composant d'acier pour utilisation structurale d'une machine et son procédé de fabrication
WO2014104113A1 (fr) * 2012-12-28 2014-07-03 新日鐵住金株式会社 Acier pour cémentation
WO2014199919A1 (fr) * 2013-06-13 2014-12-18 新日鐵住金株式会社 FIL MACHINE POUR FABRICATION DE FIL D'ACIER POUR BOULON À STRUCTURE PERLITIQUE OFFRANT UNE RÉSISTANCE À LA TRACTION DE 950 MPa À 1 600 MPA, FIL D'ACIER POUR BOULON À STRUCTURE PERLITIQUE OFFRANT UNE RÉSISTANCE À LA TRACTION DE 950 MPA À 1 600 MPa, BOULON À STRUCTURE PERLITIQUE ET PROCÉDÉS DE FABRICATION DE CEUX-CI
JP2017031492A (ja) * 2015-08-05 2017-02-09 新日鐵住金株式会社 冷延鋼板の製造方法及び冷延鋼板

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101617505B1 (ko) * 2011-04-27 2016-05-02 신닛테츠스미킨 카부시키카이샤 핫 스탬프 부재용 강판 및 그 제조 방법
KR101382675B1 (ko) * 2012-03-19 2014-04-07 주식회사 포스코 내마모성과 가공성이 우수한 저합금 열연 강판 및 그 제조방법
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JP5812048B2 (ja) * 2013-07-09 2015-11-11 Ｊｆｅスチール株式会社 焼入れ性および加工性に優れる高炭素熱延鋼板およびその製造方法
EP3040437B1 (fr) * 2013-08-30 2019-10-30 JFE Steel Corporation Composant structural mécanique et son procédé de fabrication
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KR101751530B1 (ko) 2015-12-28 2017-06-27 주식회사 포스코 공구용 강판 및 그 제조방법
TWI665310B (zh) * 2018-10-02 2019-07-11 日商新日鐵住金股份有限公司 滲碳用鋼板及滲碳用鋼板的製造方法
CN113549830B (zh) * 2021-07-16 2022-05-20 鞍钢股份有限公司 高表面硬度折弯性能优异的中碳球化索氏体工具钢及其生产方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03188217A (ja) * 1989-12-18 1991-08-16 Sumitomo Metal Ind Ltd 高炭素薄鋼板の製造方法
JPH05331534A (ja) * 1992-05-29 1993-12-14 Nisshin Steel Co Ltd 含ｂ鋼板の焼鈍方法
JPH10251757A (ja) * 1997-03-14 1998-09-22 Sumitomo Metal Ind Ltd 成形性にすぐれた高炭素薄鋼板の製造方法
JP2003328075A (ja) * 2002-05-16 2003-11-19 Nippon Steel Corp バーリング加工時のバラツキが少ない浸炭焼入れ用鋼板及びその製造方法

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4445365B2 (ja) * 2004-10-06 2010-04-07 新日本製鐵株式会社 伸びと穴拡げ性に優れた高強度薄鋼板の製造方法
JP4846308B2 (ja) * 2005-09-09 2011-12-28 新日本製鐵株式会社 使用中の硬さ変化が少ない高靭性耐摩耗鋼およびその製造方法
AU2007273767B2 (en) * 2006-07-14 2010-08-12 Nippon Steel Corporation High-strength steel sheet excellent in stretch flangeability and fatigue property

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03188217A (ja) * 1989-12-18 1991-08-16 Sumitomo Metal Ind Ltd 高炭素薄鋼板の製造方法
JPH05331534A (ja) * 1992-05-29 1993-12-14 Nisshin Steel Co Ltd 含ｂ鋼板の焼鈍方法
JPH10251757A (ja) * 1997-03-14 1998-09-22 Sumitomo Metal Ind Ltd 成形性にすぐれた高炭素薄鋼板の製造方法
JP2003328075A (ja) * 2002-05-16 2003-11-19 Nippon Steel Corp バーリング加工時のバラツキが少ない浸炭焼入れ用鋼板及びその製造方法

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010255066A (ja) * 2009-04-28 2010-11-11 Jfe Steel Corp 高炭素熱延鋼板およびその製造方法
WO2012056785A1 (fr) * 2010-10-27 2012-05-03 新日本製鐵株式会社 Acier pour durcissement de surface destiné à une utilisation structurale d'une machine, et composant d'acier pour utilisation structurale d'une machine et son procédé de fabrication
WO2014104113A1 (fr) * 2012-12-28 2014-07-03 新日鐵住金株式会社 Acier pour cémentation
JP5862802B2 (ja) * 2012-12-28 2016-02-16 新日鐵住金株式会社 浸炭用鋼
WO2014199919A1 (fr) * 2013-06-13 2014-12-18 新日鐵住金株式会社 FIL MACHINE POUR FABRICATION DE FIL D'ACIER POUR BOULON À STRUCTURE PERLITIQUE OFFRANT UNE RÉSISTANCE À LA TRACTION DE 950 MPa À 1 600 MPA, FIL D'ACIER POUR BOULON À STRUCTURE PERLITIQUE OFFRANT UNE RÉSISTANCE À LA TRACTION DE 950 MPA À 1 600 MPa, BOULON À STRUCTURE PERLITIQUE ET PROCÉDÉS DE FABRICATION DE CEUX-CI
JPWO2014199919A1 (ja) * 2013-06-13 2017-02-23 新日鐵住金株式会社 引張強さが９５０〜１６００ＭＰａであるパーライト組織ボルト用の鋼線の製造用の線材、引張強さが９５０〜１６００ＭＰａであるパーライト組織ボルト用の鋼線、パーライト組織ボルト、及び、それらの製造方法
JP2017031492A (ja) * 2015-08-05 2017-02-09 新日鐵住金株式会社 冷延鋼板の製造方法及び冷延鋼板

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KR20110038172A (ko) 2011-04-13
JPWO2010109778A1 (ja) 2012-09-27
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JP4659142B2 (ja) 2011-03-30
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