WO2022139282A1 - 가공성이 우수한 고인성 고탄소 냉연강판 및 그 제조방법 - Google Patents
가공성이 우수한 고인성 고탄소 냉연강판 및 그 제조방법 Download PDFInfo
- Publication number
- WO2022139282A1 WO2022139282A1 PCT/KR2021/018742 KR2021018742W WO2022139282A1 WO 2022139282 A1 WO2022139282 A1 WO 2022139282A1 KR 2021018742 W KR2021018742 W KR 2021018742W WO 2022139282 A1 WO2022139282 A1 WO 2022139282A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- steel sheet
- rolled steel
- cold
- comparative example
- toughness
- Prior art date
Links
- 239000010960 cold rolled steel Substances 0.000 title claims abstract description 56
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 36
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 35
- 238000000034 method Methods 0.000 title claims abstract description 28
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title abstract description 7
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 19
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 15
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 15
- 230000000717 retained effect Effects 0.000 claims abstract description 11
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 6
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 6
- 229910000831 Steel Inorganic materials 0.000 claims description 37
- 239000010959 steel Substances 0.000 claims description 37
- 238000005097 cold rolling Methods 0.000 claims description 27
- 238000010438 heat treatment Methods 0.000 claims description 27
- 238000001816 cooling Methods 0.000 claims description 22
- 238000005096 rolling process Methods 0.000 claims description 19
- 238000003303 reheating Methods 0.000 claims description 17
- 238000010791 quenching Methods 0.000 claims description 16
- 230000000171 quenching effect Effects 0.000 claims description 16
- 238000005452 bending Methods 0.000 claims description 13
- 238000005554 pickling Methods 0.000 claims description 8
- 238000004804 winding Methods 0.000 claims description 6
- 230000000052 comparative effect Effects 0.000 description 139
- 239000000203 mixture Substances 0.000 description 23
- 229910045601 alloy Inorganic materials 0.000 description 20
- 239000000956 alloy Substances 0.000 description 20
- 238000000137 annealing Methods 0.000 description 20
- 238000005279 austempering Methods 0.000 description 18
- 239000010410 layer Substances 0.000 description 18
- 230000015572 biosynthetic process Effects 0.000 description 10
- 230000007547 defect Effects 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 229910001562 pearlite Inorganic materials 0.000 description 6
- 238000005098 hot rolling Methods 0.000 description 5
- 150000001247 metal acetylides Chemical class 0.000 description 5
- 238000005204 segregation Methods 0.000 description 5
- 239000006104 solid solution Substances 0.000 description 5
- 229910000677 High-carbon steel Inorganic materials 0.000 description 4
- 239000002344 surface layer Substances 0.000 description 4
- 239000012467 final product Substances 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000016507 interphase Effects 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 238000012800 visualization Methods 0.000 description 2
- 241000219307 Atriplex rosea Species 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 238000001887 electron backscatter diffraction Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/008—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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- 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
-
- 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
- C21D1/20—Isothermal quenching, e.g. bainitic 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
- 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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- 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
- C21D2211/005—Ferrite
-
- 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
Definitions
- the present invention relates to a high-toughness high-carbon cold-rolled steel sheet having excellent workability and a method for manufacturing the same.
- Hot-rolled high carbon steel is variously applied to automotive parts such as engines, transmissions, automobile doors and seats, and industrial tool parts such as saws and knives, and the thickness of the applied final product ranges from 0.15mm to 6.0mm or more depending on the use. have up to Such hot-rolled high-carbon steel is manufactured into final parts through annealing/cold-rolling processes. Compared to thick parts, thin high-carbon steel parts with a thickness of 2.0mmt or less have a slightly more complicated manufacturing method. Applied to high-quality materials. In the case of such a high-grade material, annealing/cold rolling is repeated 2-3 times, and patenting heat treatment (Austempering) is also applied, which increases the manufacturing cost.
- annealing/cold rolling is repeated 2-3 times, and patenting heat treatment (Austempering) is also applied, which increases the manufacturing cost.
- One aspect of the present invention is to provide a high-toughness, high-carbon cold-rolled steel sheet having excellent workability and a method for manufacturing the same.
- One embodiment of the present invention is by weight%, C: 0.80 to 1.25%, Mn: 0.2 to 0.6%, Si: 0.01 to 0.4%, P: 0.005 to 0.02%, S: 0.01% or less, Al: 0.01 to 0.1 %, Cr: 0.01 to 1.0%, Sn: 0.05 to 0.5%, the remainder including Fe and other unavoidable impurities, the microstructure is by area%, retained austenite: 1 to 10%, martensite: 1 to 10%, Ferrite: 5% or less (including 0%), the remainder contains bainite, the average grain size of the microstructure is 3 to 20 ⁇ m, and the internal oxide layer formed directly under the surface has a thickness of 10 ⁇ m or less A tough high-carbon cold-rolled steel sheet is provided.
- Another embodiment of the present invention is by weight, C: 0.80 to 1.25%, Mn: 0.2 to 0.6%, Si: 0.01 to 0.4%, P: 0.005 to 0.02%, S: 0.01% or less, Al: 0.01 to 0.1 %, Cr: 0.01 to 1.0%, Sn: 0.05 to 0.5%, heating the slab containing the balance Fe and other unavoidable impurities; rough rolling the heated slab to obtain a bar; finishing rolling the bar at 850 to 950° C.
- a hot-rolled steel sheet winding the hot-rolled steel sheet after cooling to 560 to 700°C; obtaining a cold-rolled steel sheet by first cold rolling the wound hot-rolled steel sheet; spheroidizing the cold-rolled steel sheet at 650 to 740° C. for 10 to 25 hours; secondary cold rolling of the spheroidizing annealed cold rolled steel sheet; reheating the secondary cold-rolled cold-rolled steel sheet at 800 to 1000° C. for 10 to 120 seconds; And after quenching the reheated cold-rolled steel sheet to 300 ⁇ 500 °C, and then holding for 30 ⁇ 180 seconds; provides a method of manufacturing a high-toughness high-carbon cold-rolled steel sheet excellent in workability comprising a.
- the C content is an element that affects strength, toughness and microstructure formation. If the C content is less than 0.80%, a ferrite phase is formed in the hot rolled material, so that the work hardening rate is lowered during cold rolling (Full-Hard) before annealing, which is disadvantageous in securing strength. On the other hand, when the C content exceeds 1.25%, there is a problem in that proeutectoid cementite is formed and cracks are generated during cold rolling before annealing. Therefore, the C content is preferably in the range of 0.80 to 1.25%. The lower limit of the C content is more preferably 0.82%, still more preferably 0.84%, and most preferably 0.86%. The upper limit of the C content is more preferably 1.23%, and even more preferably 1.20%.
- Mn is added as a solid solution strengthening element to increase strength and secure hardenability.
- the Mn content is less than 0.2%, it may be difficult to secure a strength of 1600 MPa or more when the Mn content is small.
- the content of Mn exceeds 0.6%, it causes a decrease in toughness due to segregation/inclusion formation.
- the Mn content is preferably in the range of 0.2 to 0.6%.
- the lower limit of the Mn content is more preferably 0.22%, even more preferably 0.25%, and most preferably 0.3%.
- the upper limit of the Mn content is more preferably 0.55%, even more preferably 0.53%, and most preferably 0.5%.
- the content of Si preferably has a range of 0.01 to 0.4%.
- the lower limit of the Si content is more preferably 0.02%, more preferably 0.04%, and most preferably 0.05%.
- the upper limit of the Si content is more preferably 0.35%, still more preferably 0.30%, and most preferably 0.25%.
- the phosphorus is preferably added in an amount of 0.005% or more, but when it exceeds 0.02%, there is a problem in that workability is deteriorated due to P segregation. Therefore, the content of P is preferably in the range of 0.005 to 0.02%.
- the lower limit of the P content is more preferably 0.006%, even more preferably 0.007%, and most preferably 0.008%.
- the upper limit of the P content is more preferably 0.018%, even more preferably 0.016%, and most preferably 0.015%.
- the S content is controlled to 0.01% or less.
- the content of S is lower, the risk of brittleness due to segregation/inclusion is reduced, which is advantageous for securing toughness, so the lower limit thereof is not particularly limited.
- the content of S is more preferably 0.008% or less, even more preferably 0.006% or less, and most preferably 0.005% or less.
- Al is not only added for deoxidation, but also added for refining the bainite or martensite structure finally obtained through austenite grain refinement through AlN formation.
- the Al content is preferably 0.01 to 0.1%.
- the lower limit of the Al content is more preferably 0.015%, even more preferably 0.017%, and most preferably 0.02%.
- the upper limit of the Al content is more preferably 0.08%, even more preferably 0.06%, and most preferably 0.05%.
- the content of Cr is preferably in the range of 0.1 to 1.0%.
- the lower limit of the Cr content is more preferably 0.05%, more preferably 0.07%, and most preferably 0.1%.
- the upper limit of the Cr content is more preferably 0.9%, even more preferably 0.8%, and most preferably 0.7%.
- the Sn is segregated in the surface layer to suppress the formation of the Mn or Cr oxide layer, thereby suppressing the formation of the internal oxide layer. That is, Sn is an element for improving workability by suppressing the formation of an internal oxide layer on the surface that is generated during the manufacturing of the hot-rolled material and the subsequent heat treatment process.
- the content of Sn exceeds 0.05%, it is difficult to sufficiently obtain the above-described effect.
- the content of Sn exceeds 0.5%, there is a risk of poor workability due to excessive segregation. Therefore, the content of Sn is preferably in the range of 0.05 to 0.5%.
- the lower limit of the Sn content is more preferably 0.07%, even more preferably 0.09%, and most preferably 0.1%.
- the upper limit of the Sn content is more preferably 0.45%, even more preferably 0.43%, and most preferably 0.4%.
- the remainder may include Fe and unavoidable impurities. Inevitable impurities may be unintentionally mixed in a typical steel manufacturing process, and this cannot be entirely excluded, and those skilled in the ordinary steel manufacturing field can easily understand the meaning.
- the present invention does not entirely exclude the addition of compositions other than the above-mentioned steel composition.
- the microstructure of the high-carbon cold-rolled steel sheet of the present invention is an area%, with retained austenite: 1 to 10%, martensite: 1 to 10%, ferrite: 5% or less (including 0%), and the remainder containing bainite desirable.
- the present invention can reduce the risk of temper embrittlement while securing excellent toughness by including bainite as a matrix structure.
- the retained austenite occurs a lot in the vicinity of the triple point in the microstructure, and exhibits the effect of improving the toughness by increasing the elongation.
- the upper limit of the fraction of retained austenite is more preferably 9%, even more preferably 8%, and most preferably 7%.
- the martensite is a tissue that helps to secure high strength.
- the upper limit of the fraction of martensite is more preferably 8%, even more preferably 7%, and most preferably 5%.
- ferrite may be unavoidably formed in the manufacturing process. Since the ferrite increases the interphase hardness difference with a hard phase such as bainite or martensite to decrease workability, it is preferable to suppress it as much as possible, and in the present invention, the upper limit of the ferrite fraction is limited to 5%.
- the upper limit of the fraction of ferrite is more preferably 4%, even more preferably 3%, and most preferably 2%.
- the bainite and martensite may include tempered bainite and tempered martensite, respectively.
- the average grain size of the microstructure is preferably in the range of 3 to 20 ⁇ m in order to secure strength and bendability.
- the lower limit of the average grain size of the microstructure is more preferably 4 ⁇ m, even more preferably 5 ⁇ m, and most preferably 6 ⁇ m.
- the upper limit of the average grain size of the microstructure is more preferably 18 ⁇ m, more preferably 16 ⁇ m, and most preferably 15 ⁇ m.
- the thickness of the internal oxide layer formed directly under the surface is 10 ⁇ m or less in order to secure workability.
- the internal oxide layer means that Mn, Cr, etc. combine with oxygen to form an oxide and exist along the grain boundary of the surface tissue.
- elements having high oxide-forming ability by combining with oxygen may form an internal oxide layer.
- Such an internal oxide layer deteriorates the material of the surface portion and causes a decrease in workability such as cracks.
- the thickness of the internal oxide layer exceeds 10 ⁇ m, the poor processability is exacerbated due to the occurrence of cracks in the surface portion.
- the thickness of the internal oxide layer is more preferably 8 ⁇ m or less, even more preferably 5 ⁇ m or less, and most preferably 3 ⁇ m or less.
- the high carbon cold-rolled steel sheet according to an embodiment of the present invention provided as described above may have a tensile strength of 1600 to 2000 MPa, a hardness of 47 to 54 HRC, and an R/t of 1.0 or less during a 90° bending test, through which, Excellent strength, hardness and workability can be secured at the same time.
- R is the minimum bending radius (mm) at which cracks do not occur after the 90° bending test
- t means the thickness (mm) of the steel sheet.
- the high-carbon cold-rolled steel sheet of the present invention does not generate cracks during the 180° bending test, and thus can have excellent toughness.
- the high carbon cold rolled steel sheet of the present invention may have a thickness of 0.4 ⁇ 2.0mm.
- the 180 ° bending test can be made in a manner of bending the steel material 180 ° using a round bar having an R/t of 2.0.
- the slab satisfying the above-described alloy composition is heated.
- the heating of the steel slab may be performed at 1100 ⁇ 1300 °C. If the heating temperature of the steel slab is less than 1100 °C, it may be difficult to sufficiently secure the temperature of the slab required for the plate, and if it exceeds 1300 °C, abnormal austenite growth and surface defects due to excessive scale may occur. Therefore, the heating temperature of the slab is preferably in the range of 1100 ⁇ 1300 °C.
- the lower limit of the heating temperature of the slab is more preferably 1140 °C, even more preferably 1170 °C, most preferably 1190 °C.
- the upper limit of the heating temperature of the slab is more preferably 1280 °C, even more preferably 1260 °C, most preferably 1250 °C.
- the heated slab is rough-rolled to obtain a bar.
- the rough rolling may be performed at 1000 ⁇ 1100 °C.
- the rough rolling temperature is preferably in the range of 1000 ⁇ 1100 °C.
- the lower limit of the rough rolling temperature is more preferably 1020°C, even more preferably 1030°C, and most preferably 1040°C.
- the upper limit of the rough rolling temperature is more preferably 1090°C, even more preferably 1080°C, and most preferably 1070°C.
- the bar is finish-rolled at 850 to 950° C. to obtain a hot-rolled steel sheet.
- the finish rolling temperature is preferably in the range of 850 ⁇ 950 °C.
- the lower limit of the finish rolling temperature is more preferably 855°C, even more preferably 860°C, and most preferably 870°C.
- the upper limit of the finish rolling temperature is more preferably 940°C, even more preferably 940°C, and most preferably 930°C.
- the hot-rolled steel sheet may have a thickness of 2.0 to 4.0 mm. Most of the high-end industrial/tool products have a cold-rolled steel sheet thickness of 0.4 to 2.0 mm. It is desirable to have
- the hot-rolled steel sheet is cooled to 560 to 700° C. and then wound up.
- the coiling temperature is less than 560° C.
- a uniform hot-rolled structure cannot be obtained because a bainite or martensite structure, which is a low-temperature transformation structure, appears.
- the coiling temperature is higher than 700° C., a surface defect may be caused by forming an internal oxidation layer and a decarburization layer on the surface. Therefore, the coiling temperature is preferably in the range of 560 ⁇ 700 °C.
- the lower limit of the coiling temperature is more preferably 570°C, still more preferably 580°C, and most preferably 590°C.
- the upper limit of the coiling temperature is more preferably 690°C, even more preferably 680°C, and most preferably 670°C.
- the cooling may be performed at a cooling rate of 5 to 50° C./s. If the cooling rate is less than 5 ° C / sec, the pearlite structure becomes coarse and there is a risk of cracking during cold rolling before spheroidization annealing. When the cooling rate exceeds 50 ° C / sec, Cold rolling properties may be deteriorated due to coil shape defects such as wave generation. Accordingly, the cooling rate is preferably in the range of 5 to 50° C./sec.
- the lower limit of the cooling rate is more preferably 10°C/sec, even more preferably 13°C/sec, and most preferably 15°C/sec.
- the upper limit of the cooling rate is more preferably 45°C/sec, still more preferably 40°C/sec, and most preferably 35°C/sec.
- the step of pickling the wound hot-rolled steel sheet at 200° C. or less may be further included.
- cooling to the pickling temperature may be natural cooling. It is possible to remove the scale formed on the surface of the steel sheet through the pickling.
- the pickling temperature is preferably 200° C. or less.
- the lower limit of the pickling temperature is not particularly limited, and may be, for example, room temperature.
- the microstructure of the hot-rolled steel sheet obtained through the above process may be composed of 90 area% or more of pearlite and the remainder of bainite.
- the wound hot-rolled steel sheet is first cold rolled to obtain a cold-rolled steel sheet (hereinafter, also referred to as 'unannealed cold-rolled steel sheet (Full-Hard material)').
- a cold-rolled steel sheet hereinafter, also referred to as 'unannealed cold-rolled steel sheet (Full-Hard material)'.
- the reduction ratio during the first cold rolling may be 30 to 60%. If the reduction ratio during the first cold rolling is less than 30%, material deviation in the longitudinal/width direction may be caused, and if it exceeds 60%, there is a risk of deterioration in cold ductility and cracks in the width edge part due to excessive strength increase. .
- the thickness of the cold-rolled steel sheet obtained through the first cold rolling may be 0.8 to 2.0 mm.
- the cold-rolled steel sheet is spheroidized and annealed at 650 to 740° C. for 10 to 25 hours.
- the spheroidizing annealing is a process for softening a steel sheet for secondary cold rolling and forming fine spherical carbides. If the spheroidization annealing temperature is less than 650 ° C., spheroidization of carbides hardly occurs, and when it exceeds 740 ° C., austenite reverse transformation of some structures occurs, pearlite recrystallization occurs, and a spheroidization structure is not formed. Therefore, the spheroidizing annealing temperature preferably has a range of 650 ⁇ 740 °C.
- the lower limit of the spheroidizing annealing temperature is more preferably 660°C, even more preferably 670°C, and most preferably 680°C.
- the upper limit of the spheroidizing annealing temperature is more preferably 735°C, even more preferably 730°C, and most preferably 725°C. If the spheroidization annealing time is less than 10 hours, spheroidization hardly occurs, and when it exceeds 25 hours, the formed spheroidal carbide grows and becomes coarse, and there is a problem in causing deterioration of heat treatment properties of austempering, which is a post process.
- the spheroidizing annealing time is preferably in the range of 10 to 25 hours.
- the lower limit of the spheroidizing annealing time is more preferably 11 hours, still more preferably 12 hours, and most preferably 14 hours.
- the upper limit of the spheroidizing annealing time is more preferably 24 hours, still more preferably 23 hours, and most preferably 22 hours.
- the spheroidizing annealed cold rolled steel sheet is subjected to secondary cold rolling.
- the secondary cold rolling is to secure a target final thickness, as well as to refine the pearlite structure.
- the reduction ratio during the secondary cold rolling may be 30-50% when considering the thickness of the final product.
- the austempering heat treatment is to form bainite as a main structure to secure target physical properties.
- Austempering heat treatment in the present invention is a process of cooling to a bainite formation temperature section after reheating to the austenizing temperature, maintaining the temperature at the temperature for a certain period of time to sufficiently form bainite, and then cooling to room temperature. More specifically, the austempering heat treatment process includes the steps of reheating the secondary cold-rolled cold-rolled steel sheet at 800-1000° C. for 10-120 seconds; And after quenching the reheated cold-rolled steel sheet to 300 ⁇ 500 °C, and then holding for 30 ⁇ 180 seconds; includes.
- the reheating temperature is preferably in the range of 800 ⁇ 1000 °C.
- the lower limit of the reheating temperature is more preferably 820°C, even more preferably 840°C, and most preferably 850°C.
- the upper limit of the reheating temperature is more preferably 970°C, even more preferably 950°C, and most preferably 930°C.
- the reheating time is preferably in the range of 10 to 120 seconds.
- the lower limit of the reheating time is more preferably 15 seconds, still more preferably 18 seconds, and most preferably 20 seconds.
- the upper limit of the reheating time is more preferably 110 seconds, still more preferably 100 seconds, and most preferably 90 seconds.
- the reheating method is not particularly limited, and for example, high frequency induction heating or a BOX type heating furnace may be used.
- the quenching end temperature is preferably in the range of 300 ⁇ 500 °C.
- the lower limit of the quenching end temperature is more preferably 330°C, even more preferably 350°C, and most preferably 370°C.
- the upper limit of the quenching end temperature is more preferably 480°C, even more preferably 460°C, and most preferably 450°C. If the holding time is less than 30 seconds, it may be difficult to secure a sufficient bainite fraction, and if it exceeds 180 seconds, the retained austenite fraction increases and it may be difficult to obtain the properties desired by the present invention.
- the holding time is preferably in the range of 30 to 180 seconds.
- the lower limit of the holding time is more preferably 33 seconds, still more preferably 35 seconds, and most preferably 40 seconds.
- the upper limit of the holding time is more preferably 170 seconds, even more preferably 165 seconds, and most preferably 160 seconds.
- the cooling rate during the quenching may be 10 ⁇ 50 °C / s.
- the lower limit of the cooling rate during quenching is more preferably 13°C/s, even more preferably 15°C/s, and most preferably 20°C/s.
- the upper limit of the cooling rate during quenching is more preferably 45°C/s, still more preferably 40°C/s, and most preferably 35°C/s.
- the quenching method is not particularly limited, and for example, oil at 100°C or lower or water at 50°C or lower may be used.
- the type and fraction of the microstructure and the average grain size were measured using an electron microscope EBSD technique at ⁇ 2000 magnification.
- the thickness of the internal oxide layer was determined as the internal oxide layer from the surface layer to the point where the pickled grain boundaries were seen using an electron microscope photograph at a magnification of ⁇ 2000 after nital etching the surface part of the cold-rolled steel sheet, and the thickness was measured.
- Tensile strength was measured through a tensile test after taking a JIS-5 standard specimen from a cold-rolled steel sheet.
- HRC value was measured with a 150 kg load on the Rockwell hardness C scale.
- Bending properties were determined by dividing the minimum bending radius R where cracks do not occur after a 90° bending test on the cold-rolled steel sheet by the thickness t of the cold-rolled steel sheet.
- Example 1 Invention lecture 1 40 0.90 890 50 410 90 Invention example 2 Invention lecture 1 40 0.75 910 60 420 80 Invention example 3 Invention lecture 1 40 0.66 890 50 410 90 Invention Example 4 Invention lecture 1 45 0.61 910 60 420 80 Comparative Example 1 Invention lecture 1 Cracks during the 1st cold rolling Comparative Example 2 Invention lecture 1 40 0.90 890 50 410 90 Comparative Example 3 Invention lecture 1 40 0.75 890 50 410 90 Comparative Example 4 Invention lecture 1 40 0.75 890 50 410 90 Comparative Example 5 Invention lecture 1 40 0.75 890 50 410 90 Comparative Example 6 Invention lecture 1 40 0.75 890 50 410 90 Comparative Example 7 Invention lecture 1 40 0.66 750 60 .
- Inventive Examples 1 to 4 satisfies both the alloy composition and manufacturing conditions proposed by the present invention, and satisfies the microstructure and internal oxide layer thickness proposed by the present invention, thereby satisfying 1600 to 2000 MPa. It can be seen that it has a tensile strength of , a hardness of 47 to 54 HRC, and an R/t of 1.0 or less during a 90° bending test.
- Comparative Example 1 satisfies the alloy composition of the present invention, but the hot rolling coiling temperature is 500 ° C., which is out of 560 to 700 ° C, which is the condition of the present invention. It can be seen that the longitudinal microstructure is non-uniform, resulting in crack defects during the first cold rolling.
- Comparative Example 2 satisfies the alloy composition of the present invention, but the hot rolling coiling temperature is 740 ° C., which is out of 560 to 700 ° C., which is the condition of the present invention. It can be seen that the tensile strength of 1522 MPa and R/t is 1.7 due to the solid solution carbide and the coarse structure, and the tensile strength of 1600 to 2000 MPa, R/t, which is the target of the present invention, is out of 1.0 or less.
- Comparative Example 3 satisfies the alloy composition of the present invention, but the spheroidizing annealing temperature is 610 ° C., which is out of 650 to 740 ° C., which is the condition of the present invention. It can be seen that the carbon content of the tissue is lowered and the tensile strength is 1531 MPa, which is out of the target of 1600 to 2000 MPa of the present invention.
- Comparative Example 4 satisfies the alloy composition of the present invention, but the spheroidizing annealing temperature is 760 ° C., which is out of 650 to 740 ° C., which is the condition of the present invention. After heat treatment, it can be seen that the tensile strength is 1543 MPa due to the decrease in the strength of the bainite structure, which is out of the target of 1600 to 2000 MPa of the present invention.
- Comparative Example 5 satisfies the alloy composition of the present invention, but the spheroidizing annealing time is 6 hours, which is out of the condition of 10 to 25 hours of the present invention. It can be seen that the carbon content of the tissue is lowered and the tensile strength is 1558 MPa, which is out of the target of 1600 to 2000 MPa of the present invention.
- Comparative Example 6 satisfies the alloy composition of the present invention, but the spheroidizing annealing time is 32 hours, which is out of the condition of 10 to 25 hours of the present invention.
- the presence of undissolved carbides and a decrease in the matrix structure carbon content causes a decrease in strength and a decrease in bendability. Accordingly, it can be seen that the tensile strength of 1549 MPa and R/t is 2.7, which is out of the target of 1600 to 2000 MPa and 1.0 or less of the present invention.
- Comparative Example 7 satisfies the alloy composition of the present invention, but the austempering reheating temperature is 750 ° C., which is out of 800 to 1000 ° C., which is the condition of the present invention. It can be seen that it is out of the range of 1600 to 2000 MPa of the present invention.
- Comparative Example 8 satisfies the alloy composition of the present invention, but the austempering reheating temperature is 1120 ° C., which is out of 800 to 1000 ° C., which is the condition of the present invention. It can be seen that it is out of 3-20 ⁇ m, and the bendability R/t is 3.0, which is out of 1.0 or less, which is the range of the present invention.
- Comparative Example 9 satisfies the alloy composition of the present invention, but the austempering reheating time is 5 seconds, which is outside the condition of 10 to 120 seconds of the present invention. It can be seen that it is out of the range of 1600 to 2000 MPa of the present invention.
- Comparative Example 10 satisfies the alloy composition of the present invention, but the austempering reheating time is 160 seconds, which is out of the 10 to 120 seconds condition of the present invention. It can be seen that it is out of ⁇ 20 ⁇ m, and the bendability R/t is 3.0, which is out of 1.0 or less, which is the range of the present invention.
- Comparative Example 11 satisfies the alloy composition of the present invention, but the austempering heat treatment temperature is 240 ° C., which is out of 300 to 500 ° C., which is the condition of the present invention. It can be seen that it is out of the range of 1600 to 2000 MPa.
- Comparative Example 12 satisfies the alloy composition of the present invention, but the austempering heat treatment temperature is 570 ° C., which is out of 300 to 500 ° C., which is the condition of the present invention. It can be seen that it is out of the range of 1600 to 2000 MPa.
- Comparative Example 13 satisfies the alloy composition of the present invention, but the austempering heat treatment time is 18 seconds, which is out of 30 to 180 seconds, which is the condition of the present invention. It can be seen that it is out of the range of 1600 to 2000 MPa of the present invention.
- Comparative Example 14 satisfies the alloy composition of the present invention, but the austempering heat treatment time is 240 seconds, which is out of 30 to 180 seconds, which is the condition of the present invention. It can be seen that 2.3 is out of 1.0 or less, which is the range of the present invention.
- Comparative Example 15 satisfies the manufacturing conditions of the present invention, but the C content is 0.55%, which is outside the range of 0.8 to 1.25% of the present invention. can be seen to depart from
- Comparative Example 16 satisfies the manufacturing conditions of the present invention, but the C content is 1.30%, which is outside the range of 0.8 to 1.25% of the present invention. It can be seen that it is out of the range of 1600 ⁇ 2000MPa and less than 1.0.
- Comparative Example 17 satisfies the manufacturing conditions of the present invention, but the Mn content is 0.11%, which is out of the range of 0.2 to 0.6% of the present invention. can be seen to depart from
- Comparative Example 18 satisfies the manufacturing conditions of the present invention, but the Mn content is 0.86%, which is out of the range of 0.2 to 0.6% of the present invention. , and it can be seen that the bendability is also inferior.
- Comparative Example 19 satisfies the manufacturing conditions of the present invention, but the Cr content is 0.004%, which is outside the range of 0.1 to 1.0% of the present invention. It can be seen that it is outside the scope of the invention of 1600 to 2000 MPa.
- Comparative Example 20 satisfies the manufacturing conditions of the present invention, but the Cr content is 1.12%, which is outside the range of 0.1 to 1.0% of the present invention. , and it can be seen that the bendability is also inferior.
- Comparative Example 21 satisfies the manufacturing conditions of the present invention, but the Si content is 0.006%, which is outside the range of 0.01 to 0.4% of the present invention, and the Si content tensile strength is 1569 MPa, which is out of the range of 1600 to 2000 MPa can be known
- Comparative Example 22 satisfies the manufacturing conditions of the present invention, but the Si content is 0.57%, which is outside the range of 0.01 to 0.4% of the present invention. , and it can be seen that the bendability is also inferior.
- Comparative Example 23 satisfies the manufacturing conditions of the present invention, but the Al content is 0.007%, which is outside the range of 0.01 to 0.1% of the present invention. It can be seen that /t is 2.2, which is out of 1.0 or less, which is the range of the present invention.
- Comparative Example 24 satisfies the manufacturing conditions of the present invention, but the Al content is 0.18%, which is outside the range of 0.01 to 0.1% of the present invention. , and it can be seen that the bendability is also inferior.
- Comparative Example 25 satisfies the manufacturing conditions of the present invention, but the Sn content is 0.02%, which is outside the range of 0.05 to 0.5% of the present invention. It can be seen that the 90° bendability and 180° bendability are inferior.
- Comparative Example 26 satisfies the manufacturing conditions of the present invention, but the Sn content is 0.65%, which is outside the range of 0.05 to 0.5% of the present invention. It can be seen that the bendability and 180° bendability are inferior.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
강종No. | 합금조성 (중량%) | |||||||
C | Mn | Cr | Si | Al | P | S | Sn | |
발명강1 | 1.02 | 0.41 | 0.35 | 0.22 | 0.03 | 0.011 | 0.003 | 0.22 |
비교강1 | 0.55 | 0.36 | 0.39 | 0.21 | 0.04 | 0.010 | 0.002 | 0.21 |
비교강2 | 1.30 | 0.43 | 0.28 | 0.19 | 0.03 | 0.009 | 0.002 | 0.29 |
비교강3 | 0.98 | 0.11 | 0.23 | 0.23 | 0.03 | 0.011 | 0.002 | 0.35 |
비교강4 | 1.05 | 0.86 | 0.42 | 0.25 | 0.04 | 0.012 | 0.003 | 0.25 |
비교강5 | 0.95 | 0.38 | 0.004 | 0.18 | 0.04 | 0.011 | 0.003 | 0.24 |
비교강6 | 0.97 | 0.39 | 1.12 | 0.22 | 0.03 | 0.009 | 0.002 | 0.26 |
비교강7 | 1.12 | 0.45 | 0.55 | 0.006 | 0.03 | 0.012 | 0.002 | 0.22 |
비교강8 | 1.06 | 0.41 | 0.53 | 0.57 | 0.04 | 0.011 | 0.003 | 0.31 |
비교강9 | 1.04 | 0.40 | 0.48 | 0.31 | 0.007 | 0.011 | 0.002 | 0.28 |
비교강10 | 0.99 | 0.42 | 0.34 | 0.28 | 0.18 | 0.010 | 0.002 | 0.23 |
비교강11 | 1.01 | 0.39 | 0.33 | 0.21 | 0.04 | 0.009 | 0.002 | 0.02 |
비교강12 | 0.97 | 0.41 | 0.32 | 0.20 | 0.04 | 0.01 | 0.002 | 0.65 |
구분 | 강종No. | 마무리 압연온도 (℃) |
권취 온도 (℃) |
열연강판 두께 (mm) |
1차 냉간 압연 압하율 (%) |
구상화 소둔온도 (℃) |
구상화 소둔시간 (시간) |
발명예1 | 발명강1 | 890 | 640 | 3.0 | 50 | 700 | 20 |
발명예2 | 발명강1 | 870 | 640 | 2.5 | 50 | 710 | 18 |
발명예3 | 발명강1 | 890 | 640 | 2.0 | 45 | 700 | 20 |
발명예4 | 발명강1 | 870 | 630 | 2.2 | 50 | 710 | 18 |
비교예1 | 발명강1 | 890 | 500 | 3.0 | 50 | 1차 냉연시 크랙 발생 | |
비교예2 | 발명강1 | 890 | 740 | 3.0 | 50 | 700 | 20 |
비교예3 | 발명강1 | 890 | 640 | 2.5 | 50 | 610 | 20 |
비교예4 | 발명강1 | 890 | 640 | 2.5 | 50 | 760 | 20 |
비교예5 | 발명강1 | 890 | 640 | 2.5 | 50 | 700 | 6 |
비교예6 | 발명강1 | 890 | 640 | 2.5 | 50 | 700 | 32 |
비교예7 | 발명강1 | 890 | 640 | 2.0 | 45 | 700 | 20 |
비교예8 | 발명강1 | 890 | 640 | 2.0 | 45 | 700 | 20 |
비교예9 | 발명강1 | 890 | 640 | 2.0 | 45 | 700 | 20 |
비교예10 | 발명강1 | 890 | 640 | 2.0 | 45 | 700 | 20 |
비교예11 | 발명강1 | 890 | 640 | 2.0 | 45 | 700 | 20 |
비교예12 | 발명강1 | 890 | 640 | 2.0 | 45 | 700 | 20 |
비교예13 | 발명강1 | 890 | 640 | 2.0 | 45 | 700 | 20 |
비교예14 | 발명강1 | 890 | 640 | 2.0 | 45 | 700 | 20 |
비교예15 | 비교강1 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예16 | 비교강2 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예17 | 비교강3 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예18 | 비교강4 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예19 | 비교강5 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예20 | 비교강6 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예21 | 비교강7 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예22 | 비교강8 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예23 | 비교강9 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예24 | 비교강10 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예25 | 비교강11 | 890 | 640 | 3.0 | 50 | 700 | 20 |
비교예26 | 비교강12 | 890 | 640 | 3.0 | 50 | 700 | 20 |
구분 | 강종No. | 2차 냉간 압연 압하율 (%) |
최종냉연 강판두께 (mm) |
오스템퍼링 재가열 온도 (℃) |
오스템퍼링 재가열 시간 (초) |
오스템퍼링 열처리 온도 ℃(℃) |
오스템퍼링 열처리 시간 (초) |
발명예1 | 발명강1 | 40 | 0.90 | 890 | 50 | 410 | 90 |
발명예2 | 발명강1 | 40 | 0.75 | 910 | 60 | 420 | 80 |
발명예3 | 발명강1 | 40 | 0.66 | 890 | 50 | 410 | 90 |
발명예4 | 발명강1 | 45 | 0.61 | 910 | 60 | 420 | 80 |
비교예1 | 발명강1 | 1차 냉연시 크랙 발생 | |||||
비교예2 | 발명강1 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예3 | 발명강1 | 40 | 0.75 | 890 | 50 | 410 | 90 |
비교예4 | 발명강1 | 40 | 0.75 | 890 | 50 | 410 | 90 |
비교예5 | 발명강1 | 40 | 0.75 | 890 | 50 | 410 | 90 |
비교예6 | 발명강1 | 40 | 0.75 | 890 | 50 | 410 | 90 |
비교예7 | 발명강1 | 40 | 0.66 | 750 | 60 | 410 | 90 |
비교예8 | 발명강1 | 40 | 0.66 | 1120 | 60 | 410 | 90 |
비교예9 | 발명강1 | 40 | 0.66 | 890 | 5 | 410 | 90 |
비교예10 | 발명강1 | 40 | 0.66 | 890 | 160 | 410 | 90 |
비교예11 | 발명강1 | 40 | 0.66 | 890 | 60 | 240 | 90 |
비교예12 | 발명강1 | 40 | 0.66 | 890 | 60 | 570 | 90 |
비교예13 | 발명강1 | 40 | 0.66 | 890 | 60 | 410 | 18 |
비교예14 | 발명강1 | 40 | 0.66 | 890 | 60 | 410 | 240 |
비교예15 | 비교강1 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예16 | 비교강2 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예17 | 비교강3 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예18 | 비교강4 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예19 | 비교강5 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예20 | 비교강6 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예21 | 비교강7 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예22 | 비교강8 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예23 | 비교강9 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예24 | 비교강10 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교에25 | 비교강11 | 40 | 0.90 | 890 | 50 | 410 | 90 |
비교예26 | 비교강12 | 40 | 0.90 | 890 | 50 | 410 | 90 |
구분 | 미세조직(면적%) |
평균 결정립크기 (㎛) |
내부산화층 두께 (㎛) |
기계적 물성 | ||||||
B | RA | M | F | 인장강도 (MPa) |
경도 (HRC) |
R/t | 180° 특성 |
|||
발명예1 | 90 | 3 | 6 | 1 | 12 | 1 | 1896 | 51 | 0.6 | O |
발명예2 | 91 | 4 | 4 | 1 | 11 | 2 | 1831 | 49 | 0.7 | O |
발명예3 | 88 | 4 | 6 | 2 | 8 | 2 | 1924 | 51 | 0.8 | O |
발명예4 | 90 | 3 | 5 | 2 | 9 | 3 | 1855 | 50 | 0.8 | O |
비교예1 | - | - | - | - | - | - | - | - | - | - |
비교예2 | 80 | 5 | 7 | 8 | 16 | 2 | 1522 | 45 | 1.7 | O |
비교예3 | 79 | 6 | 6 | 9 | 18 | 2 | 1531 | 46 | 2.0 | O |
비교예4 | 82 | 5 | 5 | 8 | 21 | 1 | 1543 | 45 | 2.0 | O |
비교예5 | 82 | 6 | 5 | 7 | 19 | 2 | 1558 | 46 | 2.0 | O |
비교예6 | 84 | 4 | 4 | 8 | 22 | 2 | 1549 | 46 | 2.7 | O |
비교예7 | 81 | 5 | 5 | 9 | 16 | 3 | 1516 | 45 | 2.3 | O |
비교예8 | 90 | 4 | 3 | 3 | 31 | 2 | 1880 | 50 | 3.0 | X |
비교예9 | 80 | 5 | 6 | 9 | 17 | 2 | 1522 | 46 | 2.3 | O |
비교예10 | 90 | 3 | 4 | 3 | 32 | 1 | 1896 | 50 | 3.0 | X |
비교예11 | 83 | 2 | 11 | 4 | 17 | 3 | 2075 | 55 | 1.5 | O |
비교예12 | 85 | 3 | 3 | 9 | 18 | 4 | 1467 | 43 | 1.5 | O |
비교예13 | 82 | 3 | 3 | 12 | 15 | 2 | 1488 | 44 | 1.5 | O |
비교예14 | 84 | 11 | 3 | 2 | 13 | 2 | 1866 | 49 | 2.3 | O |
비교예15 | 81 | 7 | 6 | 6 | 18 | 5 | 1369 | 19 | 0.6 | O |
비교예16 | 79 | 6 | 8 | 7 | 17 | 2 | 2153 | 56 | 2.2 | O |
비교예17 | 84 | 6 | 5 | 5 | 16 | 2 | 1521 | 45 | 0.6 | O |
비교예18 | 82 | 5 | 7 | 6 | 12 | 3 | 2061 | 54 | 1.7 | O |
비교예19 | 85 | 7 | 5 | 3 | 22 | 2 | 1543 | 46 | 0.6 | O |
비교예20 | 84 | 4 | 6 | 6 | 13 | 2 | 2107 | 55 | 1.7 | O |
비교예21 | 79 | 12 | 5 | 4 | 21 | 1 | 1569 | 46 | 1.7 | O |
비교예22 | 83 | 1 | 12 | 4 | 15 | 2 | 2071 | 55 | 2.2 | O |
비교예23 | 86 | 4 | 6 | 4 | 29 | 2 | 1872 | 49 | 2.2 | O |
비교예24 | 82 | 5 | 6 | 7 | 12 | 3 | 2045 | 55 | 2.2 | O |
비교예25 | 90 | 4 | 5 | 1 | 12 | 19 | 1888 | 50 | 3.0 | X |
비교예26 | 89 | 3 | 6 | 2 | 13 | 1 | 1531 | 49 | 3.5 | X |
B: 베이나이트, RA: 잔류 오스테나이트, M: 마르텐사이트, F:페라이트 |
Claims (12)
- 중량%로, C: 0.80∼1.25%, Mn: 0.2∼0.6%, Si: 0.01~0.4%, P: 0.005∼0.02%, S: 0.01% 이하, Al: 0.01~0.1%, Cr: 0.01~1.0%, Sn: 0.05~0.5%, 잔부 Fe 및 기타 불가피한 불순물을 포함하고,미세조직은 면적%로, 잔류 오스테나이트: 1~10%, 마르텐사이트: 1~10%, 페라이트: 5% 이하(0%를 포함), 잔부 베이나이트를 포함하며,상기 미세조직의 평균 결정립 크기가 3~20㎛이고,표면 직하에 형성되는 내부산화층의 두께가 10㎛ 이하인 가공성이 우수한 고인성 고탄소 냉연강판.
- 청구항 1에 있어서,상기 냉연강판은 0.4~2.0mm의 두께를 갖는 가공성이 우수한 고인성 고탄소 냉연강판.
- 청구항 1에 있어서,상기 냉연강판은 1600~2000MPa의 인장강도, 47~54HRC의 경도 및 90° 굽힘시험시 1.0 이하의 R/t를 갖는 가공성이 우수한 고인성 고탄소 냉연강판.
- 중량%로, C: 0.80∼1.25%, Mn: 0.2∼0.6%, Si: 0.01~0.4%, P: 0.005∼0.02%, S: 0.01% 이하, Al: 0.01~0.1%, Cr: 0.01~1.0%, Sn: 0.05~0.5%, 잔부 Fe 및 기타 불가피한 불순물을 포함하는 슬라브를 가열하는 단계;상기 가열된 슬라브를 조압연하여 바를 얻는 단계;상기 바를 850~950℃에서 마무리 압연하여 열연강판을 얻는 단계;상기 열연강판을 560~700℃까지 냉각한 후 권취하는 단계;상기 권취된 열연강판을 1차 냉간압연하여 냉연강판을 얻는 단계;상기 냉연강판을 650~740℃에서 10~25시간 동안 구상화 소둔하는 단계;상기 구상화 소둔된 냉연강판을 2차 냉간압연하는 단계;상기 2차 냉간압연된 냉연강판을 800~1000℃에서 10~120초 동안 재가열하는 단계; 및상기 재가열된 냉연강판을 300~500℃까지 켄칭한 뒤, 30~180초 동안 유지하는 단계;를 포함하는 가공성이 우수한 고인성 고탄소 냉연강판의 제조방법.
- 청구항 4에 있어서,상기 슬라브의 가열은 1100~1300℃에서 행하여지는 가공성이 우수한 고인성 고탄소 냉연강판의 제조방법.
- 청구항 4에 있어서,상기 조압연은 1000~1100℃에서 행하여지는 가공성이 우수한 고인성 고탄소 냉연강판의 제조방법.
- 청구항 4에 있어서,상기 열연강판은 2.0~4.0mm의 두께를 갖는 가공성이 우수한 고인성 고탄소 냉연강판의 제조방법.
- 청구항 4에 있어서,상기 냉각은 5~50℃/s의 냉각속도로 행하여지는 가공성이 우수한 고인성 고탄소 냉연강판의 제조방법.
- 청구항 4에 있어서,상기 권취 후, 상기 권취된 열연강판을 200℃ 이하에서 산세하는 단계를 추가로 포함하는 가공성이 우수한 고인성 고탄소 냉연강판의 제조방법.
- 청구항 4에 있어서,상기 1차 냉간압연시 압하율은 30~60%인 가공성이 우수한 고인성 고탄소 냉연강판의 제조방법.
- 청구항 4에 있어서,상기 2차 냉간압연시 압하율은 30~50%인 가공성이 우수한 고인성 고탄소 냉연강판의 제조방법.
- 청구항 4에 있어서,상기 켄칭시 냉각속도는 10~50℃/s인 가공성이 우수한 고인성 고탄소 냉연강판의 제조방법.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP21911349.5A EP4265775A4 (en) | 2020-12-21 | 2021-12-10 | HIGH CARBON AND HIGH TOUGHNESS COLD-ROLLED STEEL SHEET HAVING EXCELLENT FORMABILITY, AND METHOD FOR MANUFACTURING SAME |
US18/268,549 US20240018621A1 (en) | 2020-12-21 | 2021-12-10 | High toughness high carbon cold rolled steel sheet having excellent formability, and method for manufacturing same |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020200179991A KR102494553B1 (ko) | 2020-12-21 | 2020-12-21 | 가공성이 우수한 고인성 고탄소 냉연강판 및 그 제조방법 |
KR10-2020-0179991 | 2020-12-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2022139282A1 true WO2022139282A1 (ko) | 2022-06-30 |
Family
ID=82159606
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/KR2021/018742 WO2022139282A1 (ko) | 2020-12-21 | 2021-12-10 | 가공성이 우수한 고인성 고탄소 냉연강판 및 그 제조방법 |
Country Status (4)
Country | Link |
---|---|
US (1) | US20240018621A1 (ko) |
EP (1) | EP4265775A4 (ko) |
KR (1) | KR102494553B1 (ko) |
WO (1) | WO2022139282A1 (ko) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH07179936A (ja) * | 1993-12-24 | 1995-07-18 | Aichi Steel Works Ltd | 熱へたり性に優れた薄板ばね用鋼 |
KR100847045B1 (ko) * | 2006-12-27 | 2008-07-17 | 주식회사 포스코 | 항복강도 및 냉간압연성이 우수한 고탄소 강판 및 그 제조방법 |
KR20140044925A (ko) * | 2011-09-09 | 2014-04-15 | 신닛테츠스미킨 카부시키카이샤 | 중탄소 강판, 켄칭 부재 및 그들의 제조 방법 |
KR20160071462A (ko) * | 2013-11-19 | 2016-06-21 | 신닛테츠스미킨 카부시키카이샤 | 봉강 |
JP2018048374A (ja) * | 2016-09-21 | 2018-03-29 | 株式会社神戸製鋼所 | 高炭素鋼板部材およびその製造方法 |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101799712B1 (ko) * | 2013-11-22 | 2017-11-20 | 신닛테츠스미킨 카부시키카이샤 | 고탄소 강판 및 그 제조 방법 |
-
2020
- 2020-12-21 KR KR1020200179991A patent/KR102494553B1/ko active IP Right Grant
-
2021
- 2021-12-10 EP EP21911349.5A patent/EP4265775A4/en active Pending
- 2021-12-10 US US18/268,549 patent/US20240018621A1/en active Pending
- 2021-12-10 WO PCT/KR2021/018742 patent/WO2022139282A1/ko active Application Filing
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH07179936A (ja) * | 1993-12-24 | 1995-07-18 | Aichi Steel Works Ltd | 熱へたり性に優れた薄板ばね用鋼 |
KR100847045B1 (ko) * | 2006-12-27 | 2008-07-17 | 주식회사 포스코 | 항복강도 및 냉간압연성이 우수한 고탄소 강판 및 그 제조방법 |
KR20140044925A (ko) * | 2011-09-09 | 2014-04-15 | 신닛테츠스미킨 카부시키카이샤 | 중탄소 강판, 켄칭 부재 및 그들의 제조 방법 |
KR20160071462A (ko) * | 2013-11-19 | 2016-06-21 | 신닛테츠스미킨 카부시키카이샤 | 봉강 |
JP2018048374A (ja) * | 2016-09-21 | 2018-03-29 | 株式会社神戸製鋼所 | 高炭素鋼板部材およびその製造方法 |
Non-Patent Citations (1)
Title |
---|
See also references of EP4265775A4 * |
Also Published As
Publication number | Publication date |
---|---|
EP4265775A1 (en) | 2023-10-25 |
KR102494553B1 (ko) | 2023-02-06 |
EP4265775A4 (en) | 2024-05-01 |
US20240018621A1 (en) | 2024-01-18 |
KR20220089396A (ko) | 2022-06-28 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2020067752A1 (ko) | 구멍확장성이 높은 고강도 냉연강판, 고강도 용융아연도금강판 및 이들의 제조방법 | |
WO2017111524A1 (ko) | 구멍확장성이 우수한 초고강도 강판 및 그 제조방법 | |
WO2017222159A1 (ko) | 가공성이 우수한 고강도 냉연강판 및 그 제조 방법 | |
WO2020111856A2 (ko) | 연성 및 저온 인성이 우수한 고강도 강재 및 이의 제조방법 | |
WO2021112488A1 (ko) | 내구성이 우수한 후물 복합조직강 및 그 제조방법 | |
WO2019124781A1 (ko) | 상온내시효성 및 소부경화성이 우수한 아연계 도금강판 및 그 제조방법 | |
WO2021117989A1 (ko) | 초고강도 냉연강판 및 이의 제조방법 | |
WO2020226301A1 (ko) | 전단가공성이 우수한 초고강도 강판 및 그 제조방법 | |
WO2018110906A1 (ko) | 표면품질이 우수한 고탄소 열연강판 및 이의 제조방법 | |
WO2013154254A1 (ko) | 재질 균일성이 우수한 고탄소 열연강판 및 이의 제조방법 | |
WO2020111857A1 (ko) | 크리프 강도가 우수한 크롬-몰리브덴 강판 및 그 제조방법 | |
WO2022139214A1 (ko) | 강도 및 내식성이 향상된 마르텐사이트계 스테인리스강 및 이의 제조 방법 | |
WO2019088552A1 (ko) | 냉간압연성이 우수한 초고강도 냉연강판 및 이의 제조방법 | |
WO2017111303A1 (ko) | 굽힘 가공성이 우수한 고강도 열연 강판 및 그 제조 방법 | |
WO2021261884A1 (ko) | 생산성 및 원가 절감 효과가 우수한 고강도 오스테나이트계 스테인리스강 및 이의 제조방법 | |
WO2022139282A1 (ko) | 가공성이 우수한 고인성 고탄소 냉연강판 및 그 제조방법 | |
WO2020130614A2 (ko) | 구멍확장성이 우수한 고강도 열연강판 및 그 제조방법 | |
WO2024136317A1 (ko) | 냉연강판 및 그 제조방법 | |
WO2024144040A1 (ko) | 초고장력 냉연강판 및 그 제조방법 | |
WO2024080657A1 (ko) | 강판 및 이의 제조방법 | |
WO2023234508A1 (ko) | 핫 스탬핑 부품 및 이의 제조 방법 | |
WO2023018270A1 (ko) | 고강도 고인성 강판 및 그 제조방법 | |
WO2023234509A1 (ko) | 핫 스탬핑 부품 및 이의 제조 방법 | |
WO2024072023A1 (ko) | 냉연강판 및 그 제조방법 | |
WO2023048450A1 (ko) | 표면 품질이 우수하고 재질 편차가 적은 고강도 냉연강판 및 이의 제조 방법 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 21911349 Country of ref document: EP Kind code of ref document: A1 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 18268549 Country of ref document: US |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2021911349 Country of ref document: EP |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
ENP | Entry into the national phase |
Ref document number: 2021911349 Country of ref document: EP Effective date: 20230721 |