WO2023003188A1 - 구멍확장성 및 연성이 우수한 고강도 강판 및 이의 제조방법 - Google Patents
구멍확장성 및 연성이 우수한 고강도 강판 및 이의 제조방법 Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 120
- 239000010959 steel Substances 0.000 title claims abstract description 120
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 32
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 64
- 238000000137 annealing Methods 0.000 claims abstract description 37
- 238000005097 cold rolling Methods 0.000 claims abstract description 21
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 20
- 238000001816 cooling Methods 0.000 claims description 85
- 238000010438 heat treatment Methods 0.000 claims description 29
- 239000011572 manganese Substances 0.000 claims description 18
- 229910001566 austenite Inorganic materials 0.000 claims description 16
- 239000011651 chromium Substances 0.000 claims description 16
- 238000002791 soaking Methods 0.000 claims description 16
- 239000010936 titanium Substances 0.000 claims description 16
- 229910052799 carbon Inorganic materials 0.000 claims description 15
- 239000010955 niobium Substances 0.000 claims description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 13
- 238000005098 hot rolling Methods 0.000 claims description 13
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 239000010960 cold rolled steel Substances 0.000 claims description 11
- 230000009467 reduction Effects 0.000 claims description 9
- 229910052748 manganese Inorganic materials 0.000 claims description 8
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 229910052796 boron Inorganic materials 0.000 claims description 7
- 229910052717 sulfur Inorganic materials 0.000 claims description 7
- 239000011593 sulfur Substances 0.000 claims description 7
- 238000004804 winding Methods 0.000 claims description 7
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 6
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 6
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 239000011733 molybdenum Substances 0.000 claims description 6
- 229910052758 niobium Inorganic materials 0.000 claims description 6
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims description 6
- 239000011574 phosphorus Substances 0.000 claims description 6
- 229910052710 silicon Inorganic materials 0.000 claims description 6
- 239000010703 silicon Substances 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- 230000000717 retained effect Effects 0.000 claims description 4
- 238000000034 method Methods 0.000 abstract description 29
- 230000008569 process Effects 0.000 abstract description 22
- 239000000463 material Substances 0.000 abstract description 12
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- 229910045601 alloy Inorganic materials 0.000 description 6
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- 229910001563 bainite Inorganic materials 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
- 230000006872 improvement Effects 0.000 description 6
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- 229910001562 pearlite Inorganic materials 0.000 description 3
- 238000005266 casting Methods 0.000 description 2
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- 238000009792 diffusion process Methods 0.000 description 2
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- 238000010583 slow cooling Methods 0.000 description 2
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- 239000011800 void material Substances 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910000797 Ultra-high-strength steel Inorganic materials 0.000 description 1
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- 229910052802 copper Inorganic materials 0.000 description 1
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- 238000010899 nucleation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 description 1
- 229910001568 polygonal ferrite Inorganic materials 0.000 description 1
- 239000000047 product Substances 0.000 description 1
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- 230000037303 wrinkles Effects 0.000 description 1
Images
Classifications
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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
- C21D9/46—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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C47/00—Winding-up, coiling or winding-off metal wire, metal band or other flexible metal material characterised by features relevant to metal processing only
- B21C47/02—Winding-up or coiling
-
- 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
-
- 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
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
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- 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
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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
- 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
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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
- C21D9/0062—Heat-treating apparatus with a cooling or quenching zone
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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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- C22C38/00—Ferrous alloys, e.g. steel alloys
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- 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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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
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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
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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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
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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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
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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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
- C21D2211/005—Ferrite
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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
Definitions
- the present invention relates to a steel suitable as a material for automobiles, and more particularly, to a high-strength steel sheet having excellent hole expandability and ductility and a manufacturing method thereof.
- high-strength steel with excellent strength is used as a material for structural members such as members, seat rails, and pillars to improve the impact resistance of the vehicle body.
- the higher the strength of the steel the more advantageous it is to absorb impact energy.
- the higher the strength the lower the elongation, thereby reducing the molding processability.
- the yield strength is excessively high, the flow of material from the mold during molding is reduced, resulting in poor moldability and an increase in manufacturing cost.
- hole expandability is required for smooth molding, but high-strength steel has low hole expandability, resulting in cracks and cracks during molding. I have a problem with the same glitch. As such, if the hole expandability is poor, there is a concern that the safety of the occupant may be threatened as the part is easily destroyed due to cracks occurring in the part forming part when the car crashes.
- high-strength steels used as materials for automobiles include Dual Phase Steel (DP Steel), Transformation Induced Plasticity Steel (TRIP Steel), and Complex Phase Steel (CP Steel). steel), ferrite-bainite steel (Ferrite Bainite steel, FB steel), etc.
- DP steel an ultra-high-strength steel, has a low yield ratio of approximately 0.5 to 0.6, so it is easy to process and has the advantage of having a high elongation next to TRIP steel. Accordingly, it is mainly applied to door outers, seat rails, seat belts, suspensions, arms, wheel disks, and the like.
- TRIP steel is characterized by excellent formability (high ductility) by having a yield ratio in the range of 0.57 to 0.67, and is therefore suitable for parts requiring high formability such as members, roofs, seat belts, and bumper rails.
- CP steel is applied to side panels and underbody stiffeners due to its low yield ratio, high elongation and bending workability, and FB steel has excellent hole expandability and is mainly applied to suspension lower arms or wheel discs.
- DP steel is mainly composed of ferrite with excellent ductility and hard phases with high strength (martensite phase, bainite phase), and a small amount of retained austenite may be present.
- This DP steel has excellent characteristics such as low yield strength, high tensile strength, low yield ratio (Yield Ratio, YR), high work hardening rate, high ductility, continuous yield behavior, room temperature aging resistance, baking hardenability, and the like.
- high-strength steel with high hole expandability can be manufactured by controlling the fraction, recrystallization degree, and distribution uniformity of each phase.
- DP steel for automobiles is manufactured as a final product through an annealing process after manufacturing a slab through a steelmaking and casting process, then obtaining a hot-rolled coil by performing [heating-rough rolling-finish hot rolling] on the slab.
- the annealing process is a process mainly performed in the manufacture of cold-rolled steel sheet, and the cold-rolled steel sheet is pickled to remove the surface scale of the hot-rolled coil, cold-rolled at a constant reduction rate at room temperature, and then annealed and necessary. It is manufactured through an additional temper rolling process according to.
- Cold-rolled steel sheets (cold-rolled products) obtained by cold rolling are in a very hardened state and are not suitable for manufacturing parts that require workability. can make it
- the steel sheet (cold-rolled material) is heated to approximately 650 to 850° C. in a heating furnace and maintained for a predetermined time to lower hardness and improve workability through recrystallization and phase transformation.
- the steel sheet that has not undergone the annealing process has high hardness, particularly surface hardness, and lacks workability
- the steel sheet subjected to the annealing process has a recrystallized structure, so that hardness, yield point, and tensile strength are lowered to improve workability.
- ferrite is completely recrystallized in the heating process during continuous annealing to produce equiaxed crystals, so that austenite is created and grown in equiaxed crystals in the subsequent process, so that the grain size is reduced. It is advantageous to form a small, uniform austenite phase.
- Patent Document 1 proposes a method according to microstructure, and specifically, for a composite structure steel sheet mainly composed of martensite phase, fine precipitation with a grain size of 1 to 100 nm is deposited inside the structure. A method of dispersing copper particles is disclosed. However, since this technique requires the addition of 2 to 5% of Cu to obtain fine precipitated particles, there is a concern that red-hot brittleness may occur due to a large amount of Cu and the manufacturing cost is excessively increased.
- Patent Document 2 has a structure containing 2 to 10 area% of pearlite using ferrite as a base structure, and strengthens precipitation through the addition of carbon nitride forming elements (ex, Ti, etc.) and refines grains to increase strength An improved steel sheet is disclosed. While the steel sheet is good in terms of hole expandability, it has limitations in further increasing tensile strength, and has a problem in that cracks occur during fresh forming due to high yield strength and low ductility.
- Patent Document 3 discloses a method of manufacturing a cold-rolled steel sheet that simultaneously obtains high strength and high ductility using a tempered martensite phase and has an excellent plate shape after continuous annealing, but the content of carbon (C) in the steel is 0.2% or more In addition to the problem of poor weldability, there is a possibility that dent defects in the furnace due to the addition of a large amount of Si may occur.
- Patent Document 1 Japanese Unexamined Patent Publication No. 2005-264176
- Patent Document 2 Korean Patent Publication No. 2015-0073844
- Patent Document 3 Japanese Unexamined Patent Publication No. 2010-090432
- One aspect of the present invention is to provide a high-strength steel sheet having a low yield ratio, high strength, and excellent formability such as hole expandability through improvement of ductility and a method for manufacturing the same, as a material suitable for automotive structural members, etc. is to do
- a high-strength steel sheet having excellent hole expandability, including 20 to 30% of ferrite, 5 to 15% of non-equilibrium ferrite, and the balance of martensite as a microstructure.
- Another aspect of the present invention comprising the steps of preparing a steel slab containing the above-described alloy composition; heating the steel slab in a temperature range of 1100 to 1300 °C; manufacturing a hot-rolled steel sheet by hot-rolling the heated steel slab; winding the hot-rolled steel sheet in a temperature range of 400 to 700° C.; cooling the hot-rolled steel sheet to room temperature after the winding; manufacturing a cold-rolled steel sheet by cold-rolling the cooled hot-rolled steel sheet; Continuously annealing the cold-rolled steel sheet; Primary cooling at an average cooling rate of 1 to 10 ° C / s to a temperature range of 570 to 630 ° C after the continuous annealing; And secondary cooling at an average cooling rate of 5 to 50 ° C to a temperature range of 300 to 400 ° C after the primary cooling,
- the continuous annealing is performed in a facility equipped with a heating zone, a soaking zone, and a cooling zone, and the heating zone and soaking zone provide a method for manufacturing a high-strength steel sheet having excellent hole expandability, characterized in that the temperature range is controlled in a range of 810 to 850 ° C.
- the steel sheet of the present invention with improved formability can prevent processing defects such as cracks or wrinkles during press forming, it has an effect of being suitably applied to parts such as structures requiring processing into complex shapes. Furthermore, it is also effective in manufacturing a material with improved collision resistance so that defects such as cracks are not easily formed when a vehicle to which such a part is applied is unavoidably collided.
- FIG. 1 shows a thermal history and a phase transformation history during continuous annealing according to an embodiment of the present invention.
- Figure 2 shows a void (void) forming mechanism in the tissue, (b) shows an interface reinforcing mechanism in the tissue of the inventive example according to an embodiment of the present invention.
- FIG 3 shows pictures of microstructures of inventive examples and comparative examples according to an embodiment of the present invention.
- the inventors of the present invention conducted in-depth research to develop a material having a level of moldability that can be suitably used for parts requiring processing into complex shapes among automotive materials.
- the present inventors derive a structure capable of resolving the difference in hardness between the soft phase and the hard phase, which affects the crack resistance of steel, and at the same time, refinement and crystal grain shape of the hard phase, which are advantageous for preventing generation and propagation of voids. It was confirmed that the target could be achieved through control, and the present invention was completed.
- the present invention introduces an intermediate phase, preferably a non-equilibrium ferrite phase, in order to solve the difference in hardness between the soft phase and the hard phase, and has technical significance in optimizing the alloy composition and manufacturing conditions in forming such a structure.
- the high-strength steel sheet with excellent hole expandability and ductility contains, by weight, carbon (C): 0.05 to 0.12%, manganese (Mn): 2.5 to 3.0%, silicon (Si): 1.2% or less ( Chromium (Cr): 0.1% or less (excluding 0%), Molybdenum (Mo): 0.1% or less (excluding 0%), Niobium (Nb): 0.1% or less (excluding 0%), Titanium (Ti): 0.1% or less (excluding 0%), Boron (B): 0.002% or less (excluding 0%), Aluminum (sol.Al): 0.02 to 0.05%, Phosphorus (P): 0.05% or less (excluding 0%), sulfur (S): 0.01% or less (excluding 0%), nitrogen (N): 0.01% or less (excluding 0%).
- the content of each element is based on weight, and the ratio of tissue is based on area.
- Carbon (C) is an important element added for solid solution strengthening, and this C contributes to improving the strength of steel by forming fine precipitates in combination with precipitated elements.
- the C may be included in 0.05 ⁇ 0.12%. More advantageously, it may be included at 0.06% or more, and may be included at 0.10% or less.
- Manganese (Mn) is an element that is advantageous for preventing hot brittleness due to the formation of FeS by precipitating sulfur (S) in steel as MnS, and for solid solution strengthening of steel.
- Mn-Band Mn oxide band
- the Mn may be included in 2.5 to 3.0%.
- Silicon (Si) is a ferrite stabilizing element, and is advantageous in securing a target level of ferrite fraction by accelerating ferrite transformation. In addition, it is effective in increasing the strength of ferrite because of its good solid solution strengthening ability, and is a useful element in securing strength without reducing the ductility of steel.
- the Si may be included in an amount of 1.2% or less, and 0% may be excluded. More advantageously, it may be included at 0.1% or more.
- Chromium (Cr) is an element that contributes to constituting the structure intended in the present invention, suppresses the formation of martensite and bainite phases during annealing heat treatment, and contributes to strength improvement by forming fine carbides. That is, the Cr has an effect of suppressing bainite that is formed competitively with non-equilibrium ferrite, and when it is contained at an appropriate level, it is advantageous in forming a non-equilibrium ferrite phase at a high temperature.
- the Cr may be included in an amount of 0.1% or less, and 0% may be excluded. More advantageously, it may contain 0.01% or more.
- Molybdenum is an element that facilitates the formation of a non-equilibrium ferrite phase by suppressing the transformation of pearlite, suppresses the formation of martensite phase during annealing heat treatment, and contributes to strength improvement by forming fine carbides.
- the Mo may be included in an amount of 0.1% or less, and 0% may be excluded. More advantageously, it may contain 0.01% or less.
- Niobium (Nb) is an element that segregates at austenite grain boundaries to suppress coarsening of austenite crystal grains during annealing heat treatment and contributes to strength improvement by forming fine carbides.
- Nb may be included in an amount of 0.1% or less, and 0% may be excluded. More advantageously, it may contain 0.01% or less.
- Titanium (Ti) is an element that forms fine carbides and contributes to securing yield strength and tensile strength.
- Ti has an effect of precipitating N in steel as TiN to suppress the formation of AlN by Al inevitably present in steel, thereby reducing the possibility of cracking during continuous casting.
- Ti may be included in an amount of 0.1% or less, and 0% may be excluded. More advantageously, it may contain 0.01% or less.
- Boron (B) is an element that retards the transformation of austenite into pearlite during cooling after annealing heat treatment, but when its content exceeds 0.002%, B is excessively concentrated on the surface and may cause deterioration of plating adhesion. .
- B may be included in an amount of 0.002% or less, and 0% may be excluded.
- Aluminum (sol.Al) is an element added for the grain size refinement effect and deoxidation of steel, and if the content is less than 0.02%, aluminum killed steel cannot be manufactured in a stable state. On the other hand, if the content exceeds 0.05%, the crystal grains are refined and the strength is improved, but the excessive formation of inclusions during steel casting operation increases the risk of surface defects of the coated steel sheet.
- the sol.Al may be included in an amount of 0.02 to 0.05%.
- Phosphorus (P) is a substitutional element having the greatest solid-solution strengthening effect, and is an element that is advantageous for improving in-plane anisotropy and securing strength without significantly deteriorating formability.
- P Phosphorus
- the content of P can be controlled to 0.05% or less, and 0% can be excluded in consideration of the level that is unavoidably added.
- S Sulfur
- S is an element that is unavoidably added as an impurity element in steel, and since it inhibits ductility, it is desirable to manage its content as low as possible.
- S since S has a problem of increasing the possibility of generating red heat brittleness, it is preferable to control the content to 0.01% or less.
- 0% can be excluded.
- Nitrogen (N) is a solid solution strengthening element, but when its content exceeds 0.01%, the risk of brittleness increases, and there is a risk of impairing performance quality by combining with Al in steel to excessively precipitate AlN.
- N may be included in an amount of 0.01% or less, and 0% may be excluded in consideration of an inevitably added level.
- the remaining component of the present invention is iron (Fe).
- Fe iron
- the steel sheet of the present invention having the above-described alloy composition may be composed of a soft phase (soft phase) ferrite and a hard phase (martensite phase), together with a non-planar ferrite phase formed at these interfaces.
- the steel sheet of the present invention may include a ferrite phase in an area fraction of 20 to 30% and a non-equilibrium ferrite phase in an area fraction of 5 to 15%, and may include a martensite phase as a remaining structure.
- a trace amount of retained austenite phase may be included.
- the non-equilibrium ferrite phase is an advantageous structure for minimizing the difference in hardness between the soft phase and the hard phase, and is a structure distinct from conventional equilibrium ferrite (polygonal ferrite).
- the non-equilibrium ferrite may be an escular ferrite or a bainitic ferrite.
- Widmanstatten ferrite, Massive ferrite, etc. may be included depending on cooling conditions.
- non-equilibrium ferrite includes relatively high C and Mn compared to equilibrium ferrite while being affected by components constituting the mother phase. For example, if the C concentration of equilibrium ferrite is assumed to be 0.02%, non-equilibrium ferrite has a higher C content of 0.03 to 0.04%.
- the hard phase formed near (near) non-equilibrium ferrite has a relatively low concentration of C and Mn, the difference in hardness between the soft phase and the hard phase is reduced, and hole expandability is improved.
- the Si concentration in non-equilibrium ferrite is as low as less than 1%, stacking fault energy increases and cross slip becomes difficult, resulting in resistance to the formation of voids due to deformation. (Fig. 2).
- the non-equilibrium ferrite phase may be included at 15% or less.
- the fraction is less than 5%, the above-mentioned effect (minimization of the hardness difference between the hard phase and the soft phase) cannot be sufficiently obtained, resulting in poor hole expandability.
- the fraction of the ferrite phase is less than 20%, it is disadvantageous to secure the ductility of the steel. On the other hand, if the fraction exceeds 30%, the fraction of the hard phase is relatively low, making it difficult to secure the target level of strength.
- the fraction of the martensite phase is not specifically limited, but may be included in an area fraction of 50% or more to secure ultra-high strength of 1100 MPa or more in tensile strength.
- the fraction of the martensite phase exceeds 75%, ductility is lowered, making it difficult to secure a target level of formability.
- the fraction of the retained austenite phase does not exceed 3%, and even if the fraction is 0%, it is revealed that there is no difficulty in securing intended physical properties.
- the steel sheet of the present invention having the above-described microstructure may have a tensile strength of 1100 MPa or more, a yield strength of 550 to 700 MPa, and an elongation (total elongation) of 12% or more, so as to have high strength and high ductility.
- the steel sheet has a hole expansion ratio (HER) of 25% or more, so that resistance to cracks that may occur during processing and resistance to impact fracture are excellent.
- HER hole expansion ratio
- the present invention can manufacture a desired steel sheet through the processes of [steel slab heating - hot rolling - winding - cold rolling - continuous annealing], and each process will be described in detail below.
- This process is performed in order to smoothly perform the subsequent hot rolling process and sufficiently obtain target physical properties of the steel sheet.
- the conditions of such a heating process there is no particular restriction on the conditions of such a heating process, and it may be a normal condition.
- the heating process may be performed in a temperature range of 1100 to 1300 °C.
- the steel slab heated according to the above may be hot-rolled to produce a hot-rolled steel sheet, and at this time, finish hot-rolling may be performed at an outlet temperature of more than Ar3 and less than 1000 ° C.
- the finish hot rolling may be performed in a temperature range of 760 ⁇ 940 °C.
- the hot-rolled steel sheet manufactured according to the above may be wound into a coil shape.
- the winding may be performed in a temperature range of 400 to 700 °C. If the coiling temperature is less than 400 ° C., martensite or non-equilibrium ferrite phase is excessively formed, resulting in an excessive increase in strength of the hot-rolled steel sheet, which may cause problems such as shape defects due to load during subsequent cold rolling. On the other hand, when the coiling temperature exceeds 700 ° C., the surface scale increases and the pickling property deteriorates.
- the coiled hot-rolled steel sheet it is preferable to cool the coiled hot-rolled steel sheet to room temperature at an average cooling rate of 0.1° C./s or less (excluding 0° C./s).
- the rolled hot-rolled steel sheet may be cooled after passing through processes such as transfer and stacking, and it should be noted that the process prior to cooling is not limited thereto.
- the hot-rolled steel sheet wound according to the above may be cold-rolled to produce a cold-rolled steel sheet.
- the cold rolling may be performed at a cold rolling reduction of 55 to 70%. If the cold rolling reduction ratio is less than 55%, the recrystallization driving force is weakened, making it difficult to obtain good recrystallized grains. On the other hand, if it exceeds 70%, the risk of cracking increases at the edge of the steel sheet, and the rolling load increases rapidly. there is a risk of
- the present invention can further promote recrystallization of ferrite in the heating section during the subsequent continuous annealing process in a state where an appropriate level of cold rolling reduction is applied during cold rolling, and from this, the formation of fine ferrite is induced to form austenite at the ferrite grain boundary. It can also be formed small and uniformly. This affects the size or distribution of the non-equilibrium structure during cooling, and is advantageous for simultaneously improving workability such as elongation and hole expandability while maintaining the strength of the final product.
- the cold rolling reduction rate can be implemented with only one cold rolling, that is, one stand, and thus, there is an economically advantageous effect as the rolling reduction is possible.
- the target reduction ratio can be achieved by repeated rolling using a reversing mill.
- the reversing mill is a type of rolling mill used for rolling thin materials, and refers to a rolling mill that rolls while reciprocating the material between a pair of rolls.
- the hot-rolled steel sheet may be pickled before the cold rolling, and the pickling process may be performed in a conventional manner.
- the continuous annealing treatment may be performed in, for example, a continuous annealing furnace (CAL).
- CAL continuous annealing furnace
- a continuous annealing furnace may consist of [heating zone - soaking zone - cooling zone (slow cooling zone and rapid cooling zone) - (overaging zone, if necessary)]. After that, it is heated to a specific temperature in the heating zone, and after reaching the target temperature, it goes through a process of holding in the soaking zone for a certain period of time.
- the temperature of the heating zone and the soaking zone can be equally controlled, which means that the end temperature of the heating zone and the starting temperature of the soaking zone are equally controlled (FIG. 1).
- the temperature of the heating zone and soaking zone may be controlled to 810 to 850 ° C.
- the temperature of the heating zone is less than 810 ° C, sufficient heat input for recrystallization cannot be applied, whereas if the temperature exceeds 850 ° C, productivity is reduced and an austenite phase is excessively formed, resulting in a hard phase after subsequent cooling The fraction of is greatly increased, and there is a concern that the ductility of the steel is inferior.
- the temperature of the soaking zone is less than 810° C.
- excessive cooling is required at the end temperature of the heating zone, which is economically unfavorable, and there is a risk that the amount of heat for recrystallization may be insufficient.
- the temperature exceeds 850 ° C. the austenite fraction becomes excessive, and there is a concern that formability may decrease due to an increase in the hard phase during cooling.
- Increasing the temperature of the soaking zone within the above-mentioned temperature range can lower the austenite stability, thereby promoting the formation of a non-equilibrium ferrite phase during subsequent cooling.
- the present invention performs stepwise cooling during cooling after passing through the heating zone and soaking zone.
- it can be configured as a non-equilibrium ferrite phase. Accordingly, in the steel sheet of the present invention, not only strength and ductility can be improved, but also workability improvement effect can be obtained by interfacial strengthening by the non-equilibrium ferrite phase.
- a target structure can be formed by cooling the cold-rolled steel sheet heat-treated according to the above, and at this time, it is preferable to perform cooling stepwise.
- the stepwise cooling may consist of primary cooling - secondary cooling, specifically, after the primary cooling at an average cooling rate of 1 to 10 ° C / s to a temperature range of 570 to 630 ° C after the continuous annealing, Secondary cooling may be performed at an average cooling rate of 5 to 50° C./s up to a temperature range of 300 to 400° C.
- the end temperature of the primary cooling is less than 570 ° C, the diffusion activity of carbon is low due to the too low temperature, and the carbon concentration in ferrite increases, while the yield ratio increases due to excessive hard phase fraction as the carbon concentration in austenite decreases. This increases the tendency of cracking during machining.
- the cooling rate between the soaking zone and the cooling zone becomes too high, causing a problem that the shape of the plate becomes non-uniform.
- an excessively high cooling rate is required during subsequent cooling (secondary cooling), and introduction of the non-equilibrium ferrite phase becomes difficult.
- the primary cooling may be performed at an average cooling rate of 1° C./s or more.
- rapid cooling may be performed at a cooling rate equal to or higher than a certain level.
- secondary cooling end temperature is less than 300 ° C.
- cooling deviation occurs in the width and length directions of the steel sheet, so that the plate shape may be deteriorated.
- the temperature exceeds 400 ° C., it is not possible to sufficiently secure the hard phase, and thus the strength may be lowered, and bainite may be formed to cause an increase in yield ratio and a decrease in elongation.
- the average cooling rate during the secondary cooling is less than 5 ° C / s, there is a risk that the fraction of the hard phase (hard phase) will be excessive, whereas if it exceeds 50 ° C / s, there is a risk that the hard phase will be insufficient.
- overaging treatment may be performed.
- the overaging treatment is a process of holding for a predetermined time after the secondary cooling end temperature, and has an effect of improving shape quality by performing uniform heat treatment in the width direction and length direction of the coil. To this end, the overaging treatment may be performed for 200 to 800 seconds.
- the temperature may be the same as the end temperature of the secondary cooling or may be performed within the end temperature range of the secondary cooling.
- the high-strength steel sheet of the present invention prepared as described above has a microstructure composed of a hard phase and a soft phase, and in particular, by maximizing ferrite recrystallization by an optimized cold rolling and annealing process, the hard phase martensite is finally recrystallized on the ferrite matrix. It may have a structure in which phases are uniformly distributed. In addition, by introducing a non-equilibrium ferrite phase into the interface between the hard phase and the soft phase, crack resistance during processing is increased.
- the steel sheet of the present invention has a high tensile strength of 1100 MPa or more, it is possible to ensure excellent formability such as hole expandability by securing a low yield ratio and high ductility.
- each steel slab was heated at 1200 ° C. for 1 hour, and then hot-rolled hot-rolled at a finish rolling temperature of 880 to 920 ° C. to prepare a hot-rolled steel sheet. Thereafter, each hot-rolled steel sheet was wound at 650° C. and then cooled to room temperature at a cooling rate of 0.1° C./s. Thereafter, the rolled hot-rolled steel sheet was subjected to cold rolling and continuous annealing under the conditions shown in Table 2 below, and then, after gradual cooling (first-secondary), overaging was performed at 360 ° C. for 520 seconds to prepare a final steel sheet. .
- the first cooling was performed at an average cooling rate of 3°C/s and the second cooling was performed at an average cooling rate of 20°C/s.
- cold rolling was performed by one stand.
- the tensile test for each test piece was performed at a strain rate of 0.01/s after taking a JIS No. 5 size tensile test piece in the direction perpendicular to the rolling direction.
- the hole expandability (HER, %) measurement test was performed according to the ISO16630 standard. Specifically, when a circular hole is punched in a test piece and then expanded using a conical punch, the hole enlargement until the crack generated at the edge of the hole penetrates in the thickness direction is expressed as a ratio to the initial hole. .
- the specimen size was 120 mm ⁇ 120 mm
- the clearance was 12%
- the punching hole diameter was 10 mm
- the punching holding load was 20 ton
- the test speed was set to 12 mm/min.
- the martensite phase and the non-equilibrium ferrite phase corresponding to the hard phase of the tissue phase were observed through SEM at 2000 and 5000 magnifications after nital etching. At this time, the size and fraction of each observed phase were measured. In addition, the fractions of each phase were measured using SEM and an image analyzer program after nital etching.
- inventive examples 1 to 6 satisfying all of the steel alloy composition and manufacturing conditions, particularly the cold rolling and continuous annealing processes proposed in the present invention sufficiently recrystallize ferrite in the annealing process after cold rolling. And, it can be seen that not only a fine hard phase is formed, but also has a yield strength suitable for plate processing while having high strength by being connected to a non-equilibrium ferrite structure at the interface, and has excellent elongation. In addition, it can be confirmed that it is possible to secure the target level of formability due to excellent hole expandability.
- Comparative Examples 1 to 6 which had a low soaking temperature during continuous annealing during the steel sheet manufacturing process, recrystallization did not occur sufficiently, and the appropriate fraction of austenite formed in the soaking zone had high stability, so that non-equilibrium ferrite was sufficiently introduced during cooling.
- ductility and/or hole expandability were poor.
- Figure 3 shows microstructure pictures of Comparative Examples 4 to 7 and Inventive Example 1.
- Inventive Example 1 a uniform and fine non-equilibrium ferrite phase is introduced into a sufficient fraction of a recrystallized ferrite matrix during primary cooling, and a certain fraction of martensite phase is formed during secondary cooling.
- Comparative Examples 4 to 7 it can be confirmed that a small amount of non-equilibrium ferrite was introduced by deviating from the conditions of the cracking zone temperature or the primary cooling end temperature during continuous annealing. Among them, in Comparative Example 4, in which the soaking zone temperature was less than 800°C and the primary cooling end temperature was considerably high, and in Comparative Example 7, in which the primary cooling end temperature was considerably high, non-equilibrium ferrite was hardly observed as less than 1%. can know
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Abstract
Description
Claims (10)
- 중량%로, 탄소(C): 0.05~0.12%, 망간(Mn): 2.5~3.0%, 실리콘(Si): 1.2% 이하(0%는 제외), 크롬(Cr): 0.1% 이하(0%는 제외), 몰리브덴(Mo): 0.1% 이하(0% 제외), 니오븀(Nb): 0.1% 이하(0%는 제외), 티타늄(Ti): 0.1% 이하(0%는 제외), 보론(B): 0.002% 이하(0%는 제외), 알루미늄(sol.Al): 0.02~0.05%, 인(P): 0.05% 이하(0%는 제외), 황(S): 0.01% 이하(0%는 제외), 질소(N): 0.01% 이하(0%는 제외), 철(Fe) 및 기타 불가피한 불순물을 포함하고,미세조직으로 면적분율 20~30%의 페라이트, 5~15%의 비평형 페라이트 및 잔부 마르텐사이트를 포함하는 구멍확장성이 우수한 고강도 강판.
- 제 1항에 있어서,상기 강판은 마르텐사이트 상을 면적분율 50% 이상으로 포함하는 구멍확장성이 우수한 고강도 강판.
- 제 1항에 있어서,상기 강판은 잔류 오스테나이트 상을 면적분율 3% 이하(0% 포함)로 더 포함하는 구멍확장성이 우수한 고강도 강판.
- 제 1항에 있어서,상기 강판은 인장강도 1100MPa 이상, 항복강도 550~700MPa, 총 연신율 12% 이상인 구멍확장성이 우수한 고강도 강판.
- 제 1항에 있어서,상기 강판은 구멍확장률(HER)이 25% 이상인 구멍확장성이 우수한 고강도 강판.
- 중량%로, 탄소(C): 0.05~0.12%, 망간(Mn): 2.5~3.0%, 실리콘(Si): 1.2% 이하(0%는 제외), 크롬(Cr): 0.1% 이하(0%는 제외), 몰리브덴(Mo): 0.1% 이하(0% 제외), 니오븀(Nb): 0.1% 이하(0%는 제외), 티타늄(Ti): 0.1% 이하(0%는 제외), 보론(B): 0.002% 이하(0%는 제외), 알루미늄(sol.Al): 0.02~0.05%, 인(P): 0.05% 이하(0%는 제외), 황(S): 0.01% 이하(0%는 제외), 질소(N): 0.01% 이하(0%는 제외), 철(Fe) 및 기타 불가피한 불순물을 포함하는 강 슬라브를 준비하는 단계;상기 강 슬라브를 1100~1300℃의 온도범위에서 가열하는 단계;상기 가열된 강 슬라브를 열간압연하여 열연강판을 제조하는 단계;상기 열연강판을 400~700℃의 온도범위에서 권취하는 단계;상기 권취 후 열연강판을 상온까지 냉각하는 단계;상기 냉각된 열연강판을 냉간압연하여 냉연강판을 제조하는 단계;상기 냉연강판을 연속소둔 처리하는 단계;상기 연속소둔 후 570~630℃의 온도범위까지 1~10℃/s의 평균 냉각속도로 1차 냉각하는 단계; 및상기 1차 냉각 후 300~400℃의 온도범위까지 5~50℃의 평균 냉각속도로 2차 냉각하는 단계를 포함하고,상기 연속소둔은 가열대, 균열대 및 냉각대가 구비된 설비에서 행하며, 상기 가열대 및 균열대는 810~850℃의 온도범위로 제어되는 것을 특징으로 하는 구멍확장성이 우수한 고강도 강판의 제조방법.
- 제 6항에 있어서,상기 열간압연은 출구측 온도 Ar3 이상~1000℃이하에서 마무리 열간압연하는 것인 구멍확장성이 우수한 고강도 강판의 제조방법.
- 제 6항에 있어서,상기 권취 후 냉각은 0.1℃/s 이하(0℃ 제외)의 냉각속도로 행하는 것인 구멍확장성이 우수한 고강도 강판의 제조방법.
- 제 6항에 있어서,상기 냉간압연은 1 스탠드(stand)로 행하며, 총 압하율이 55~70%인 것을 특징으로 하는 구멍확장성이 우수한 고강도 강판의 제조방법.
- 제 6항에 있어서,상기 2차 냉각 후 과시효 처리하는 단계를 더 포함하며,상기 과시효 처리는 200~800초간 행하는 것인 구멍확장성이 우수한 고강도 강판의 제조방법.
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PCT/KR2022/008874 WO2023003188A1 (ko) | 2021-07-20 | 2022-06-22 | 구멍확장성 및 연성이 우수한 고강도 강판 및 이의 제조방법 |
Country Status (4)
Country | Link |
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EP (1) | EP4375391A1 (ko) |
KR (1) | KR20230014121A (ko) |
CN (1) | CN117043382A (ko) |
WO (1) | WO2023003188A1 (ko) |
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JP2005264176A (ja) | 2004-03-16 | 2005-09-29 | Jfe Steel Kk | 加工性の良好な高強度鋼およびその製造方法 |
JP2010090432A (ja) | 2008-10-08 | 2010-04-22 | Jfe Steel Corp | 延性に優れる超高強度冷延鋼板およびその製造方法 |
US20110024004A1 (en) * | 2008-04-10 | 2011-02-03 | Masafumi Azuma | High-strength steel sheet and galvanized steel sheet having very good balance between hole expansibility and ductility, and also excellent in fatigue resistance, and methods of producing the steel sheets |
KR20120127733A (ko) * | 2010-03-29 | 2012-11-23 | 가부시키가이샤 고베 세이코쇼 | 가공성이 우수한 초고강도 강판 및 그의 제조 방법 |
KR20130032917A (ko) * | 2010-09-16 | 2013-04-02 | 신닛테츠스미킨 카부시키카이샤 | 연성과 신장 플랜지성이 우수한 고강도 강판, 고강도 아연 도금 강판 및 이들의 제조 방법 |
KR20150073844A (ko) | 2013-12-20 | 2015-07-01 | 주식회사 포스코 | 구멍확장성이 우수한 석출강화형 강판 및 그 제조방법 |
KR20170106414A (ko) * | 2015-02-24 | 2017-09-20 | 신닛테츠스미킨 카부시키카이샤 | 냉연 강판 및 그 제조 방법 |
KR20180132889A (ko) * | 2016-04-19 | 2018-12-12 | 제이에프이 스틸 가부시키가이샤 | 강판, 도금 강판 및, 그들의 제조 방법 |
-
2021
- 2021-07-20 KR KR1020210094848A patent/KR20230014121A/ko unknown
-
2022
- 2022-06-22 EP EP22846060.6A patent/EP4375391A1/en active Pending
- 2022-06-22 CN CN202280017433.0A patent/CN117043382A/zh active Pending
- 2022-06-22 WO PCT/KR2022/008874 patent/WO2023003188A1/ko active Application Filing
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2005264176A (ja) | 2004-03-16 | 2005-09-29 | Jfe Steel Kk | 加工性の良好な高強度鋼およびその製造方法 |
US20110024004A1 (en) * | 2008-04-10 | 2011-02-03 | Masafumi Azuma | High-strength steel sheet and galvanized steel sheet having very good balance between hole expansibility and ductility, and also excellent in fatigue resistance, and methods of producing the steel sheets |
JP2010090432A (ja) | 2008-10-08 | 2010-04-22 | Jfe Steel Corp | 延性に優れる超高強度冷延鋼板およびその製造方法 |
KR20120127733A (ko) * | 2010-03-29 | 2012-11-23 | 가부시키가이샤 고베 세이코쇼 | 가공성이 우수한 초고강도 강판 및 그의 제조 방법 |
KR20130032917A (ko) * | 2010-09-16 | 2013-04-02 | 신닛테츠스미킨 카부시키카이샤 | 연성과 신장 플랜지성이 우수한 고강도 강판, 고강도 아연 도금 강판 및 이들의 제조 방법 |
KR20150073844A (ko) | 2013-12-20 | 2015-07-01 | 주식회사 포스코 | 구멍확장성이 우수한 석출강화형 강판 및 그 제조방법 |
KR20170106414A (ko) * | 2015-02-24 | 2017-09-20 | 신닛테츠스미킨 카부시키카이샤 | 냉연 강판 및 그 제조 방법 |
KR20180132889A (ko) * | 2016-04-19 | 2018-12-12 | 제이에프이 스틸 가부시키가이샤 | 강판, 도금 강판 및, 그들의 제조 방법 |
Also Published As
Publication number | Publication date |
---|---|
KR20230014121A (ko) | 2023-01-30 |
CN117043382A (zh) | 2023-11-10 |
EP4375391A1 (en) | 2024-05-29 |
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