WO2022131589A1 - 열처리 특성 및 수소지연파괴 특성이 우수한 고강도 냉간압조용 선재, 열처리부품 및 이들의 제조방법 - Google Patents
열처리 특성 및 수소지연파괴 특성이 우수한 고강도 냉간압조용 선재, 열처리부품 및 이들의 제조방법 Download PDFInfo
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- WO2022131589A1 WO2022131589A1 PCT/KR2021/016963 KR2021016963W WO2022131589A1 WO 2022131589 A1 WO2022131589 A1 WO 2022131589A1 KR 2021016963 W KR2021016963 W KR 2021016963W WO 2022131589 A1 WO2022131589 A1 WO 2022131589A1
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- Prior art keywords
- heat treatment
- wire rod
- delayed fracture
- hydrogen
- excellent heat
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- 238000010438 heat treatment Methods 0.000 title claims abstract description 59
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 25
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 25
- 239000001257 hydrogen Substances 0.000 title claims abstract description 25
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 21
- 230000003111 delayed effect Effects 0.000 title claims abstract description 20
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 29
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims abstract description 16
- 239000012535 impurity Substances 0.000 claims abstract description 14
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 13
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 12
- 229910001566 austenite Inorganic materials 0.000 claims description 25
- 238000005097 cold rolling Methods 0.000 claims description 23
- 229910052804 chromium Inorganic materials 0.000 claims description 20
- 229910052750 molybdenum Inorganic materials 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 16
- 229910052799 carbon Inorganic materials 0.000 claims description 15
- 238000001816 cooling Methods 0.000 claims description 14
- 229910052748 manganese Inorganic materials 0.000 claims description 14
- 229910052757 nitrogen Inorganic materials 0.000 claims description 14
- 229910052782 aluminium Inorganic materials 0.000 claims description 13
- 229910052710 silicon Inorganic materials 0.000 claims description 13
- 229910000831 Steel Inorganic materials 0.000 claims description 12
- 239000010959 steel Substances 0.000 claims description 12
- 238000010791 quenching Methods 0.000 claims description 9
- 230000000171 quenching effect Effects 0.000 claims description 9
- 238000005491 wire drawing Methods 0.000 claims description 8
- 238000005098 hot rolling Methods 0.000 claims description 4
- 239000011651 chromium Substances 0.000 description 21
- 239000011572 manganese Substances 0.000 description 15
- 239000000203 mixture Substances 0.000 description 12
- 238000005496 tempering Methods 0.000 description 12
- 229910045601 alloy Inorganic materials 0.000 description 9
- 239000000956 alloy Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- 150000001247 metal acetylides Chemical class 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 230000008569 process Effects 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910017464 nitrogen compound Inorganic materials 0.000 description 4
- 150000002830 nitrogen compounds Chemical class 0.000 description 4
- 238000004804 winding Methods 0.000 description 4
- 238000010273 cold forging Methods 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000009863 impact test Methods 0.000 description 2
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- -1 aluminum nitrides Chemical class 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000035755 proliferation Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
- C21D1/22—Martempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
- C21D1/58—Oils
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- 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
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/02—Hardening by precipitation
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- 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
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
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- 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
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
- C21D7/10—Modifying the physical properties of iron or steel by deformation by cold working of the whole cross-section, e.g. of concrete reinforcing bars
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- 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
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0075—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rods of limited length
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- 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
- C21D9/0093—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for screws; for bolts
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
- C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
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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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
Definitions
- the present invention relates to a high-strength cold-rolling wire rod having excellent heat treatment characteristics and hydrogen delayed fracture characteristics, a heat treatment component, and a manufacturing method thereof. It relates to a wire rod for rolling, a heat treatment component, and a manufacturing method thereof.
- the wire rod for cold rolling is divided into a wire rod for a process omission type in which heat treatment and processing processes are omitted, and a wire rod for high-strength cold rolling that can achieve weight reduction of parts.
- High-strength cold-rolling wire rods are manufactured into heat-treated parts, such as mechanical structures and automobile parts, through spheroidizing heat treatment, cold rolling, and quenching and tempering processes.
- the metal structure of a general wire rod is mainly made of pearlite, and there is an inconvenience of having to heat-treat for a long time in order to dissolve cementite during austenitization heat treatment.
- a tempered martensite microstructure is formed, and it is difficult to use such a tempered martensite microstructure because it is very sensitive to hydrogen delayed fracture at high strength of 1300 MPa or more.
- the present invention is to provide a high-strength cold-rolling wire rod, heat-treated parts, and a manufacturing method thereof having excellent heat treatment characteristics and hydrogen delayed fracture characteristics.
- the present specification is, in weight %, C: 0.3 to 0.6%, Si: 0.05 to 0.3%, Mn: 0.2 to 1.0%, Cr: 0.5 to 2.0%, Mo: 0.5 to 2.0% , Al: 0.02 to 0.05%, N: 0.01 to 0.03% Contains remaining Fe and other impurities, and the microstructure contains 80% or more of bainite, 1 to 15% of pearlite, and 0.1 to 2% of martensite by area fraction Disclosed is a high-strength cold-rolling wire rod having excellent heat treatment characteristics and hydrogen-delayed fracture characteristics containing aluminum nitride having a diameter of 5 to 50 nm and at least 2 ⁇ 10 19 pieces/m 3 .
- the prior austenite average grain diameter may be made of 10 ⁇ m or less.
- martensite may be included in the former austenite grain boundary 60% or more.
- the present specification is by weight %, C: 0.3 to 0.6%, Si: 0.05 to 0.3%, Mn: 0.2 to 1.0%, Cr: 0.5 to 2.0%, Mo: 0.5 to 2.0%, Al: 0.02 to 0.05%, N: 0.01 to 0.03%
- the billet containing the remaining Fe and other impurities is heated at 1000 to 1200° C., hot rolled to a finish hot rolling temperature of 750 to 950° C., and 0.2 to Including cooling at a cooling rate of 1.0 ° C.
- the microstructure of the cooled wire rod comprises 80% or more of bainite, 1 to 15% of pearlite, and 0.1 to 2% of martensite as an area fraction
- Disclosed is a method for manufacturing a high-strength cold-rolling wire rod having excellent heat treatment characteristics and hydrogen-delayed fracture characteristics including 2 ⁇ 10 19 pieces/m 3 or more of aluminum nitride having a diameter of 5 to 50 nm.
- the present specification is by weight %, C: 0.3 to 0.6%, Si: 0.05 to 0.3%, Mn: 0.2 to 1.0%, Cr: 0.5 to 2.0%, Mo: 0.5 to 2.0%, Al: 0.02 to 0.05%, N: 0.01 to 0.03% Contains the remaining Fe and other impurities, and the microstructure is an area fraction, and contains 90% or more of tempered martensite, aluminum having a diameter of 5 to 50 nm Disclosed is a heat treatment part having excellent heat treatment characteristics and hydrogen delayed fracture characteristics containing more than 2 ⁇ 10 19 pieces/m 3 nitride.
- the prior austenite average grain diameter may be made of 5 ⁇ m or less.
- the heat-treated parts having excellent hydrogen-delayed fracture characteristics may have a tensile strength of 1400 MPa or more and an impact toughness of 60 J or more.
- the present specification is by weight %, C: 0.3 to 0.6%, Si: 0.05 to 0.3%, Mn: 0.2 to 1.0%, Cr: 0.5 to 2.0%, Mo: 0.5 to 2.0%, Al: 0.02 to 0.05%, N: 0.01 to 0.03% including the remaining Fe and other impurities, and the microstructure is 80% or more of bainite by area fraction, 1 to 15% of pearlite and 0.1 to 2 of martensite %, wherein the martensite is prepared as a steel wire by performing spheroidizing heat treatment and wire drawing at least once on a wire rod containing 60% or more in the old austenite grain boundary, and cold forging the prepared steel wire into a part, and the prepared part Heating at 800 to 900 ° C. for 1,000 to 2,000 seconds, quenching the heated part at 50 to 150 ° C., and tempering the quenched part at 500 to 600 ° C. for 3,000 to 10,000 seconds.
- Disclosed is a method for manufacturing
- the microstructure contains 80% or more of bainite, 1 to 15% of pearlite, and 0.1 to 2% of martensite by area fraction, the austenitizing heat treatment can be performed quickly, thereby Energy used in the heat treatment process can be reduced.
- the resistance to delayed hydrogen fracture can be improved.
- 1 is a graph showing the tensile strength of each invention example and comparative example.
- the present specification is, in weight %, C: 0.3 to 0.6%, Si: 0.05 to 0.3%, Mn: 0.2 to 1.0%, Cr: 0.5 to 2.0%, Mo: 0.5 to 2.0% , Al: 0.02 to 0.05%, N: 0.01 to 0.03% Contains remaining Fe and other impurities, and the microstructure contains 80% or more of bainite, 1 to 15% of pearlite, and 0.1 to 2% of martensite by area fraction Disclosed is a high-strength cold-rolling wire rod having excellent heat treatment characteristics and hydrogen-delayed fracture characteristics containing aluminum nitride having a diameter of 5 to 50 nm and at least 2 ⁇ 10 19 pieces/m 3 .
- the high-strength cold-rolling wire rod having excellent heat treatment characteristics and hydrogen-delayed fracture characteristics according to the present invention is, by weight, C: 0.3 to 0.6%, Si: 0.05 to 0.3%, Mn: 0.2 to 1.0%, Cr: 0.5 to 2.0% , Mo: 0.5 to 2.0%, Al: 0.02 to 0.05%, N: 0.01 to 0.03%, including the remainder of Fe and other impurities.
- C is an element added to secure product strength.
- the C content is less than 0.3%, it is difficult to secure the target strength, and it is not easy to secure sufficient hardenability after the final Q/T (Quenching/Tempering) heat treatment.
- the content of C exceeds 0.6%, there is a problem in that the fatigue life is reduced due to excessive generation of carbides. Accordingly, the upper limit of the C content in the present invention is limited to 0.6%.
- Si is not only used for deoxidation of steel, but also is an element advantageous for securing strength through solid solution strengthening.
- Si is added in an amount of 0.05% or more in order to deoxidize and secure strength.
- the upper limit of the Si content in the present invention is limited to 0.3%.
- Mn is advantageous in securing strength by improving hardenability of parts, and is an element that increases rollability and reduces brittleness. In order to secure sufficient strength, 0.2% or more is added. However, when the content is excessive, it is easy to generate a hard structure during cooling after hot rolling, and there is a problem in that a large amount of MnS inclusions are generated and fatigue properties are deteriorated. Accordingly, the upper limit of the Mn content in the present invention is limited to 1.0%.
- the upper limit of the Cr content in the present invention is limited to 2.0%.
- Mo is an element that improves hardenability through precipitation and solid solution strengthening by precipitation of fine carbides.
- the improvement of hardenability due to Mo is more effective than Mn and Cr.
- the Mo content is less than 0.5%, it is difficult to secure strength because fine carbides are not sufficiently precipitated during Q/T heat treatment.
- the content is excessive, the hardenability is excessively increased, and the shape of the part is distorted after quenching, so that an additional process is required to correct this, or there is a problem that microcracks are defective inside the part. Accordingly, the upper limit of the Mo content in the present invention is limited to 2.0%.
- Al is an element frequently used as a deoxidizer in the steelmaking process. Al reacts with N to form aluminum nitride (AlN), which is a nitrogen compound, and refines austenite grains.
- AlN aluminum nitride
- the content of Al is less than 0.02%, the number of nitrogen compounds is not sufficient, so that grain refinement is not easy.
- the content is excessive, there is a problem in that the generation of non-metallic inclusions such as alumina is excessively generated, and the occurrence of defects in the steel material is deepened. Accordingly, the upper limit of the Al content in the present invention is limited to 0.05%.
- N is an element used instead of an expensive alloying element for grain refinement. N reacts with Al to form aluminum nitride (AlN), a nitrogen compound, and refines austenite grains.
- AlN aluminum nitride
- the content of N is less than 0.01%, the number of nitrogen compounds is not sufficient, so that grain refinement is not easy.
- the upper limit of the N content in the present invention is limited to 0.03%.
- the remaining component of the present invention is iron (Fe).
- Fe iron
- the impurities are known to any person skilled in the art of a conventional manufacturing process, all details thereof are not specifically mentioned in the present specification.
- V vanadium
- CHQ Cold Heading Quality
- the microstructure of the wire rod for cold rolling includes 80% or more of bainite, 1 to 15% of pearlite, and 0.1 to 2% of martensite, as an area fraction, and when the microstructure is made in this way, austen It is possible to reduce the heat treatment time for dissolving cementite during the nitriding heat treatment.
- the microstructure may include 2 ⁇ 10 19 pieces/m 3 or more of aluminum nitride having a diameter of 5 to 50 nm, and an average old austenite grain diameter of 10 ⁇ m or less.
- aluminum nitride with a diameter of 5 to 50 nm is included in 2 ⁇ 10 19 pieces/m 3 , austenite grains can be refined and resistance to delayed hydrogen fracture can be improved.
- the old austenite grain boundary of the wire rod means the grain boundary of the austenite structure of the wire rod after winding and before cooling.
- martensite may be included in the former austenite grain boundary 60% or more.
- the tensile strength of 1400Mpa and the impact toughness of 60J or more can be secured.
- the present inventors found that, when the relationship between C, Cr, and Mo contents satisfies a specific condition, the strength and resistance to hydrogen delayed fracture of the wire rod for cold rolling could be further improved, and the following component relation was derived.
- the wire rod for cold rolling according to an embodiment of the present invention may satisfy the above-described alloy composition and, at the same time, satisfy the following formula (1).
- C, Cr, and Mo mean the weight% of each element.
- 0 is substituted for the numerical value of the corresponding alloy component.
- Microcarbides capable of trapping hydrogen include CrC and MoC carbides containing Cr and Mo as main components, respectively. Only by securing a certain level of the number of such fine carbides, it is possible to secure a strength of 1400 MPa or more at a tempering temperature of 500 to 600° C. and maximize the hydrogen trap effect. In consideration of this, if the alloy composition is controlled to satisfy Equation (1), the strength and resistance to hydrogen delayed fracture of heat-treated parts can be improved at a high tempering temperature (500 to 600° C.).
- the method for manufacturing a high-strength cold-rolling wire rod having excellent heat treatment characteristics and hydrogen-delayed fracture characteristics includes the steps of heating a billet satisfying the above-described component system, preparing the heated billet as a wire rod, and cooling the wire rod may include the step of
- the billet satisfies the above-described component system, and heating may be performed at 1000 to 1200°C.
- the billet may satisfy the above-mentioned formula (1).
- the heated billet may be finish hot rolled and wound at 750 to 950° C. to prepare a wire rod.
- the wire rod may be cooled at a cooling rate of 0.2 to 1.0° C./s so that the average austenite grain size after winding is 10 ⁇ m or less.
- the cooling method is not particularly limited, but may be performed by air cooling.
- the microstructure of the cooled wire rod may include, as an area fraction, bainite: 80% or more, pearlite: 1 to 15%, and martensite: 0.1 to 2%, and the area ratio of martensite formed at the prior austenite grain boundary is It may be more than 60%.
- the old austenite grain boundary means the grain boundary of the austenite structure of the wire rod after winding and before cooling.
- the microstructure of the cooled wire rod may contain 2 ⁇ 10 19 pieces/m 3 or more of aluminum nitride having a diameter of 5 to 50 nm.
- the step of lowering the strength by spheroidizing the cooled wire rod following the manufacturing method of the cold-rolling wire rod to lower the strength, cold forging the wire rod may include a step of preparing the part, heating the part, quenching the heated part, and tempering the quenched part, and after spheroidizing heat treatment, wire drawing may be performed one or more times. Each step is described in detail below.
- the cooled wire rod may be subjected to spheroidizing heat treatment and wire drawing at least once to prepare a steel wire.
- the spheroidizing heat treatment is appropriately performed to impart a processing amount to the steel material prior to wire drawing, and the wire drawing may be appropriately performed in consideration of the wire drawing limit.
- the steel wire may be cold forged and provided as a part.
- the part include screws and bolts, and in the case of the bolt, the diameter of the body portion may be 12 to 30 mm.
- the part may then be heated to a high temperature.
- the heating of the component is a step of re-dissolving the carbide precipitated during wire rolling, and may be heated so that the composition of the alloy component is homogeneous and the average austenite grain size is 5 ⁇ m or less.
- the part may be heated between 800 and 900° C., and the heating time may be between 1000 and 2000 seconds.
- the heated part may be quenched to 50 to 150°C.
- the quenching method is not particularly limited, but may be performed by immersing the heated part in oil at 50 to 150°C.
- the step of tempering the quenched part is a step for controlling the final microstructure of the heat-treated part to be tempered martensite.
- the tempering step may be performed by tempering at 500 to 600 °C. At this time, the tempering time may be 3000 to 10000 seconds.
- the heat-treated parts having excellent heat treatment characteristics and hydrogen-delayed fracture characteristics according to the present invention manufactured by the above-described manufacturing method are, by weight, C: 0.3 to 0.6%, Si: 0.05 to 0.3%, Mn: 0.2 to 1.0%, Cr: 0.5 to 2.0%, Mo: 0.5 to 2.0%, Al: 0.02 to 0.05%, N: 0.01 to 0.03% Containing the remaining Fe and other impurities, the microstructure includes 90% or more of tempered martensite as an area fraction, , 2 ⁇ 10 19 pieces/m 3 or more of aluminum nitride having a diameter of 5 to 50 nm.
- the prior austenite average grain diameter may be made of 5 ⁇ m or less.
- the prior austenite average grain diameter means the average grain diameter of the austenite structure before quenching after being heated in the step of heating the part.
- the tensile strength may be 1400 MPa or more
- the impact toughness may be 60 J or more
- the final part having a body diameter of 12 to 30 mm may have a tensile strength of 1400 MPa or more, and an impact toughness of 60 J or more.
- the heat treatment component satisfying the above-described alloy composition may satisfy the following formula (1).
- Equation (1) The reason for limitation to Equation (1) is the same as described above, so it is omitted.
- C, Cr, and Mo mean the weight % of each element.
- the billet having the composition shown in Table 1 was heated to 1000 to 1200 °C, and then finished rolling at 750 to 950 °C and wound up at 730 to 900 °C. After winding, the cooling rate was 0.2 to 1°C/s. After cooling was completed, the microstructure of each wire rod contained 80% or more of bainite, 1 to 15% of pearlite, 0.1 to 2% of martensite as an area fraction, and the ratio of martensite formed at the grain boundaries of prior austenite was 60% or more. lost. In addition, more than 2 ⁇ 10 19 pieces/m 3 of aluminum nitride with a size of 5 to 50 nm appeared.
- the value of formula (1) is 6.65 or more, the ratio of grain boundary martensite is 60% or more, and the aluminum nitride having a size of 5 to 50 nm is 2 ⁇ 10 19 pieces/m 3 or more.
- the value of formula (1) is less than 6.65, the ratio of intergranular martensite is less than 60%, or aluminum nitride of 5 to 50 nm size is less than 2 ⁇ 10 19 pieces/m 3 , or the alloy composition is C: 0.3 to 0.6%, Si: 0.05 to 0.3%, Mn: 0.2 to 1.0%, Cr: 0.5 to 2.0%, Mo: 0.5 to 2.0%, Al: 0.02 to 0.05%, N: 0.01 to 0.03%.
- a high-strength cold-rolling wire rod a heat-treated component, and a method for manufacturing the same, which are excellent in heat treatment characteristics and hydrogen-delayed fracture characteristics.
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Abstract
Description
구분 | 합금조성 (wt%) | 식(1) | 입계 마르텐사이트 비율(%) | AlN 수 (/m3) |
||||||
C | Si | Mn | Cr | Mo | Al | N | ||||
발명예1 | 0.32 | 0.11 | 0.71 | 1.23 | 1.19 | 0.04 | 0.015 | 6.747 | 63 | 4.3x1019 |
발명예2 | 0.41 | 0.11 | 0.62 | 1.01 | 1.12 | 0.03 | 0.016 | 6.986 | 62 | 3.4x1019 |
발명예3 | 0.56 | 0.12 | 0.82 | 0.81 | 0.92 | 0.03 | 0.016 | 7.326 | 64 | 3.6x1019 |
발명예4 | 0.42 | 0.10 | 0.72 | 1.52 | 0.95 | 0.03 | 0.017 | 7.109 | 63 | 5.0x1019 |
발명예5 | 0.40 | 0.11 | 0.56 | 0.57 | 1.45 | 0.03 | 0.014 | 7.365 | 70 | 3.1x1019 |
비교예1 | 0.32 | 0.13 | 0.69 | 1.25 | 0.85 | 0.03 | 0.016 | 5.849 | 65 | 3.6x1019 |
비교예2 | 0.40 | 0.11 | 0.65 | 0.94 | 1.19 | 0.04 | 0.015 | 7.033 | 54 | 3.7x1019 |
비교예3 | 0.54 | 0.11 | 0.75 | 0.83 | 0.94 | 0.03 | 0.009 | 7.256 | 68 | 1.9x1019 |
비교예4 | 0.43 | 0.13 | 0.66 | 2.12 | 1.05 | 0.03 | 0.016 | 8.051 | 72 | 3.4x1019 |
비교예5 | 0.41 | 0.10 | 0.76 | 0.77 | 2.21 | 0.04 | 0.015 | 9.689 | 74 | 3.7x1019 |
Claims (8)
- 중량%로, C: 0.3 내지 0.6%, Si: 0.05 내지 0.3%, Mn: 0.2 내지 1.0%, Cr: 0.5 내지 2.0%, Mo: 0.5 내지 2.0%, Al: 0.02 내지 0.05%, N: 0.01 내지 0.03% 나머지 Fe 및 기타 불순물을 포함하고,미세조직은 면적분율로, 베이나이트 80% 이상, 펄라이트 1 내지 15% 및 마르텐사이트 0.1 내지 2%를 포함하며,직경 5 내지 50nm 크기의 알루미늄 질화물을 2Х1019개/m3 이상 포함하는 열처리 특성 및 수소지연파괴 특성이 우수한 고강도 냉간압조용 선재.
- 제1항에 있어서,구오스테나이트 평균 결정립 직경이 10㎛ 이하인 열처리 특성 및 수소지연파괴 특성이 우수한 고강도 냉간압조용 선재.
- 제1항에 있어서,상기 마르텐사이트는 구오스테나이트 입계에 60% 이상 포함되는 열처리 특성 및 수소지연파괴 특성이 우수한 고강도 냉간압조용 선재.
- 중량%로, C: 0.3 내지 0.6%, Si: 0.05 내지 0.3%, Mn: 0.2 내지 1.0%, Cr: 0.5 내지 2.0%, Mo: 0.5 내지 2.0%, Al: 0.02 내지 0.05%, N: 0.01 내지 0.03% 나머지 Fe 및 기타 불순물을 포함하는 빌렛을 1000 내지 1200℃에서 가열하고,마무리 열간압연 온도 750 내지 950℃으로 열간압연하고,0.2 내지 1.0℃/s의 냉각속도로 냉각하는 것을 포함하고,냉각된 선재의 미세조직은 미세조직은 면적분율로, 베이나이트 80% 이상, 펄라이트 1 내지 15% 및 마르텐사이트 0.1 내지 2%를 포함하며,직경 5 내지 50nm 크기의 알루미늄 질화물을 2Х1019개/m3 이상 포함하는 열처리 특성 및 수소지연파괴 특성이 우수한 고강도 냉간압조용 선재의 제조방법.
- 중량%로, C: 0.3 내지 0.6%, Si: 0.05 내지 0.3%, Mn: 0.2 내지 1.0%, Cr: 0.5 내지 2.0%, Mo: 0.5 내지 2.0%, Al: 0.02 내지 0.05%, N: 0.01 내지 0.03% 나머지 Fe 및 기타 불순물을 포함하고,미세조직은 면적분율로, 템퍼드 마르텐사이트 90% 이상 포함하며, 직경 5 내지 50nm 크기의 알루미늄 질화물을 2Х1019개/m3 이상 포함하는 열처리 특성 및 수소지연파괴 특성이 우수한 열처리부품.
- 제5항에 있어서,구오스테나이트 평균 결정립 직경이 5㎛ 이하인 열처리 특성 및 수소지연파괴 특성이 우수한 열처리부품.
- 제5항에 있어서,인장강도가 1400MPa 이상이며, 충격인성이 60J 이상인 열처리 특성 및 수소지연파괴 특성이 우수한 열처리부품.
- 중량%로, C: 0.3 내지 0.6%, Si: 0.05 내지 0.3%, Mn: 0.2 내지 1.0%, Cr: 0.5 내지 2.0%, Mo: 0.5 내지 2.0%, Al: 0.02 내지 0.05%, N: 0.01 내지 0.03% 나머지 Fe 및 기타 불순물을 포함하고, 미세조직은 면적분율로, 베이나이트 80% 이상, 펄라이트 1 내지 15% 및 마르텐사이트 0.1 내지 2%를 포함하며, 상기 마르텐사이트는 구오스테나이트 입계에 60% 이상 포함되는 선재를 구상화 열처리 및 신선 가공을 1회 이상 수행하여 강선으로 마련하고,마련된 강선을 냉간단조하여 부품으로 마련하고,마련된 부품을 800 내지 900℃에서 1,000 내지 2,000초간 가열하고,상기 가열된 부품을 50 내지 150℃에 담금질하고,상기 담금질된 부품을 500 내지 600℃에서 3,000 내지 10,000초간 뜨임하는 열처리 특성 및 수소지연파괴 특성이 우수한 열처리부품의 제조방법.
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US18/267,224 US20240052467A1 (en) | 2020-12-14 | 2021-11-18 | High-strength wire rod for cold heading with superior heat treatment characteristics and resistance of hydrogen-delayed fracture characteristics, heat-treated component, and method for manufacturing same |
CN202180087541.0A CN116724131A (zh) | 2020-12-14 | 2021-11-18 | 具有优异的热处理特性和抗氢致延迟断裂性的冷镦用高强度线材、热处理组件及其制造方法 |
EP21906894.7A EP4261313A4 (en) | 2020-12-14 | 2021-11-18 | HIGH STRENGTH COLD START WIRE WIRE WITH EXCELLENT HEAT TREATMENT PROPERTIES AND HYDROGEN-RETARDED FRACTURE PROPERTIES, HEAT TREATMENT COMPONENT AND MANUFACTURING PROCESS THEREFOR |
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