WO2001023624A1 - Sheet steel and method for producing sheet steel - Google Patents
Sheet steel and method for producing sheet steel Download PDFInfo
- Publication number
- WO2001023624A1 WO2001023624A1 PCT/JP2000/006639 JP0006639W WO0123624A1 WO 2001023624 A1 WO2001023624 A1 WO 2001023624A1 JP 0006639 W JP0006639 W JP 0006639W WO 0123624 A1 WO0123624 A1 WO 0123624A1
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- WO
- WIPO (PCT)
- Prior art keywords
- less
- rolling
- steel sheet
- cooling
- producing
- Prior art date
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 187
- 239000010959 steel Substances 0.000 title claims abstract description 187
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 78
- 238000001816 cooling Methods 0.000 claims abstract description 206
- 238000005096 rolling process Methods 0.000 claims abstract description 127
- 238000004804 winding Methods 0.000 claims abstract description 35
- 238000005098 hot rolling Methods 0.000 claims description 43
- 230000009466 transformation Effects 0.000 claims description 42
- 238000000034 method Methods 0.000 claims description 29
- 230000009467 reduction Effects 0.000 claims description 23
- 238000010438 heat treatment Methods 0.000 claims description 20
- 238000010791 quenching Methods 0.000 claims description 20
- 230000000171 quenching effect Effects 0.000 claims description 19
- 229910052748 manganese Inorganic materials 0.000 claims description 18
- 229910052720 vanadium Inorganic materials 0.000 claims description 18
- 229910052758 niobium Inorganic materials 0.000 claims description 15
- 229910052719 titanium Inorganic materials 0.000 claims description 15
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- 229910052750 molybdenum Inorganic materials 0.000 claims description 14
- 238000000137 annealing Methods 0.000 claims description 13
- 238000010924 continuous production Methods 0.000 claims description 12
- 238000005204 segregation Methods 0.000 claims description 11
- 229910052726 zirconium Inorganic materials 0.000 claims description 11
- 229910052791 calcium Inorganic materials 0.000 claims description 10
- 229910052698 phosphorus Inorganic materials 0.000 claims description 10
- 229910052796 boron Inorganic materials 0.000 claims description 9
- 229910052804 chromium Inorganic materials 0.000 claims description 9
- 230000006698 induction Effects 0.000 claims description 9
- 238000005554 pickling Methods 0.000 claims description 9
- 238000005097 cold rolling Methods 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 7
- 238000003303 reheating Methods 0.000 claims description 7
- 238000012546 transfer Methods 0.000 claims description 7
- 230000001186 cumulative effect Effects 0.000 claims description 6
- 239000000463 material Substances 0.000 description 41
- 230000000694 effects Effects 0.000 description 26
- 229910000859 α-Fe Inorganic materials 0.000 description 24
- 239000013078 crystal Substances 0.000 description 23
- 229910001562 pearlite Inorganic materials 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 17
- 239000000203 mixture Substances 0.000 description 13
- 239000010960 cold rolled steel Substances 0.000 description 12
- 239000000126 substance Substances 0.000 description 12
- 239000000047 product Substances 0.000 description 8
- 239000006104 solid solution Substances 0.000 description 8
- 238000005728 strengthening Methods 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 7
- 230000006872 improvement Effects 0.000 description 7
- 229910001566 austenite Inorganic materials 0.000 description 6
- 230000001771 impaired effect Effects 0.000 description 6
- 238000010583 slow cooling Methods 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000007670 refining Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 230000002542 deteriorative effect Effects 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 238000005246 galvanizing Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 150000003568 thioethers Chemical class 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 101100474383 Escherichia coli (strain K12) rpsO gene Proteins 0.000 description 1
- 229910001335 Galvanized steel Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 229920001074 Tenite Polymers 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000012733 comparative method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000008397 galvanized steel Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 235000019362 perlite Nutrition 0.000 description 1
- 239000010451 perlite Substances 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
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- 239000007779 soft material Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/40—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling foils which present special problems, e.g. because of thinness
-
- 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
- C21D9/48—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals deep-drawing sheets
-
- 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
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0426—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
- C21D8/0463—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—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
- 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
- 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
- C21D2211/009—Pearlite
Definitions
- the present invention relates to a thin steel sheet such as a hot-rolled steel sheet and a cold-rolled steel sheet, and a method for producing a thin steel sheet.
- Thin steel sheets such as hot-rolled steel sheets and cold-rolled steel sheets are used in a wide range of fields such as automobiles, home appliances, and industrial machinery. Since such thin steel sheets are often used after being subjected to some kind of processing, various workabilities are required.
- the workability required for the hot-rolled steel sheet and the cold-rolled steel sheet is, for example,
- high-tensile steels high-strength hot-rolled steel sheets
- high stretch flangeability during burring is required.
- high r-values and elongation at break are required for cold-rolled steel sheets that are drawn at a strength of 440 MPa or less.
- Japanese Patent Application Laid-Open No. 9-241742 proposes a method of improving the uniformity of mechanical properties in a hot-rolled coil by continuous hot-rolling.
- This is a technology that uses a hot-rolling continuity process to improve the material at the front and rear ends of the rolled steel sheet and to eliminate variations in the material inside the coil.
- the improvement of workability of materials is described in JP-B-61-15929 and JP-B-63-6752 by controlling the cooling rate and winding temperature after hot rolling to improve the workability of high tensile hot rolled steel sheets. Methods have been proposed to improve the quality.
- Japanese Patent Application Laid-Open No. 5-112831 proposes a method of performing high pressure reduction and rapid cooling by hot rolling. .
- This technology is intended to improve the r-value of cold-rolled steel sheets by making the final rolling reduction of hot-rolled steel 30% or more and quenching immediately after the end of rolling, so as to refine the crystal grains of the hot-rolled steel sheets. Things.
- the material property (measured value at the center of the coil width) obtained by the technology described in Japanese Patent Application Laid-Open No. 9-241742, which aims to eliminate the variation in the material inside the coil, is the same as that of a 30K to 70K class steel plate.
- TS fluctuation value
- the average cooling rate immediately after rolling which is a feature of this technology, is 90 to 105 t: / sec for 1 second from the start of cooling, and 65 to 80 ° C / sec for 3 seconds from the start of cooling. sec.
- the hot rolling conditions of the actual machine at such a cooling rate, it was not possible to refine the crystal grains of the steel plate, especially at the top of the rolling mill.
- Patent No. 255555336 has been proposed as a prior art.
- the cooling rate after finish rolling was set to 30 to 150 ° C / s, and the winding temperature was set to 250 to 540.
- a technique for improving the elongation-flangeability of 0 to 60 K class high tensile steel is disclosed.
- the cooling rate should be at least 50: / s within 3 seconds immediately after cooling, preferably at 150 ° CZs or less, depending on the steel composition. It is proposed to improve the stretch-flange properties of 50-70K class high tensile steel by stopping (at 410-620), then air cooling, and winding at 350-500. are doing.
- Japanese Patent Application Laid-Open No. Sho 61-7338029 combines a method of strengthening cooling after rolling and a method of refining crystal grains, and rapidly cooling a steel sheet having a fine structure by adjusting rolling conditions. Is characterized by further miniaturization. That is, during or immediately after rolling, the steel is rapidly cooled from a state in which ferrite is slightly generated, and the transformed structure is divided by ferrite to obtain a very fine structure, thereby obtaining a high-strength, high-toughness steel sheet.
- the microstructure of the steel sheet is refined by rolling and then quenching, and the characteristics are unstable due to fluctuations in the manufacturing conditions It is easy to be.
- the present invention is excellent in workability including elongation flangeability, is suitable for press working with strict dimensional accuracy, and has uniform mechanical properties and various characteristic levels. It is another object of the present invention to provide a method for producing a thin steel sheet that can exhibit an excellent sheet shape.
- the present invention provides a method for producing a thin steel sheet, which comprises a step of producing a rough bar, a step of producing a steel strip, a step of primary cooling, a step of secondary cooling and a step of winding. provide.
- the step of producing the rough bar comprises rough rolling a continuous production slab having a C content of 0.8% or less by mass.
- the step of producing the steel strip comprises finish rolling the rough bar at (Ar 3 transformation point ⁇ 20) at the above finishing temperature.
- the step of quenching comprises cooling the steel strip after the finish rolling to a temperature of 500 to 800 at a cooling rate exceeding 120 ° C./sec.
- the winding step comprises winding the steel strip after the secondary cooling at a winding temperature of 400 to 750.
- the coarse bar is replaced by (Acm Transformation point-20) Finish rolling at a finishing temperature of ° C or higher.
- the present invention has low defects in molding into a product shape, enables product sampling from a coil at a high yield, and has excellent workability such as stretch-flange property, elongation at break, and impact resistance.
- the present invention provides a method for producing a thin steel sheet having a step of producing a slab, a step of producing a hot rolled sheet, a primary cooling step, a secondary cooling step, and a winding step.
- C 0.05 to 0.14%
- Si 0.5% or less
- Mn 0.5 to 2.5% by mass% by continuous production that performs segregation reduction processing.
- P not more than 0.05%
- S not more than 0.1%
- ⁇ not more than 0.005%
- Ca not more than 0.0005%.
- the step of producing a hot-rolled sheet comprises hot-rolling the slab at a finish rolling end temperature of Ar 3 or more.
- the primary cooling step consists of starting primary cooling at a cooling rate of 100 to 2000: Zs within 2 seconds after hot rolling, and cooling the hot rolled sheet to a temperature range of 600 to 750. Process;
- the secondary cooling step comprises cooling the hot rolled sheet at a cooling rate of less than 50 t: Zs after cooling to the temperature range.
- the secondary-cooled hot-rolled sheet is wound at a temperature of 450 to 65 O :.
- an object of the present invention is to provide a method for producing a steel sheet capable of stably obtaining desired strength characteristics.
- the present invention comprises a hot rolling step and a cooling step.
- the hot rolling process is performed in the following mass%: C: 0.03 to 0.12%, Si: l% or less, Mn: 5 to 2%, P: 0.02% or less, S: 0. 0 1% or less, Nb: 0.005 to 1%, V: 0.005 to 0.1%, Ti: 0.005 to 0.1% It consists of hot rolling the steel contained at a temperature of 1070 ° C or less with a cumulative reduction of 30% or more.
- the hot rolling process is performed in the following mass%: C: 0.03 to 0.12%, Si: 1%
- Hot rolling may be performed at a rate of 30% or more.
- the cooling step comprises cooling within 6 seconds after the end of rolling, at an average cooling rate of 8 O ⁇ Zs or more, over 5 O Ot, and 70 o: or less.
- FIG. 1 is a diagram showing the effect of the primary cooling start time on the mechanical properties according to Best Mode 2.
- FIG. 2 is a diagram showing the relationship between tensile strength and hole expansion ratio according to Best Mode 2.
- Figure 3 shows the effect of the rapid (primary) cooling stop temperature on the strength characteristics (TS, YS) according to Best Mode 3.
- Fig. 4 is a diagram showing the effect of the rapid (primary) cooling stop temperature on the strength characteristics (E1) according to Best Mode 3.
- Figure 5 shows the effect of the rapid (primary) cooling stop temperature on the strength characteristics (TS ⁇ E 1) according to Best Mode 3.
- Fig. 6 is a diagram showing the effect of the rapid (primary) cooling stop temperature on the strength characteristics (YR) according to Best Mode 3.
- Figure 7 shows the effect of rapid (primary) cooling stop temperature on toughness according to Best Mode 3.
- Method for producing a thin steel sheet Best Mode 1 by mass%, a C content of 0.8% or less continuous ⁇ Concrete slabs, a step of producing a rough rolling to rough bar, the crude bar, (Ar 3 A step of finish rolling at the above-mentioned finishing temperature at the transformation point-20) to produce a steel strip, and a step of rapidly cooling the steel strip after the finish rolling at a cooling rate exceeding 120 / sec at 120 to a temperature of 500 to 800. Winding the steel strip after the quenching at a winding temperature of 400 to 750 ° C.
- the continuous production slab can also be obtained by continuously producing steel containing 0.8% or less by mass, Si: 2.5% or less, and Mn: 3.0% or less by mass%.
- the continuous structure slab contains, by mass%, C: 0.8% or less, Si: 2.5% or less, Mn: 3.0% or less, and one of Ti, Nb, V, Mo, Zr, and Cr. It can also be obtained by continuously forming steel containing 0.01 to 0.2% of a kind or more.
- Continuously manufactured slabs contain, by mass%, C: 0.8% or less, Si: 2.5% or less, Mn: 3.0% or less, and steel containing 0.005% or less of one or more of Ca and B. It can also be obtained by building.
- the continuous production slab contains, by mass%, C: 0.8% or less, Si: 2.5% or less, Mn: 3.0% or less, and Ti, Nb, V, Mo, Zr, It can also be obtained by continuously forming steel containing at least one of Cr in an amount of 0.01 to 0.2% and at least one of Ca and B at 0.005% or less.
- C is an additive element for ensuring the strength of the steel sheet. However, if it is contained excessively, the workability is significantly deteriorated, and if it exceeds 1%, the workability is deteriorated. Therefore, the C content should be 1% or less.
- Si is a solid solution strengthening element, but if its addition exceeds 2.5%, the surface properties deteriorate. Therefore, the amount of Si is preferably set to 2.5% or less.
- Mn is an element that improves the toughness of the steel sheet and has a solid solution strengthening action, but has an adverse effect on workability. If the Mn content exceeds 3%, the strength increases and the workability deteriorates significantly. Therefore, the Mn content is preferably set to 3% or less.
- P is an element that has the effect of strengthening the solid solution. However, if added in excess of 0.2%, grain boundary embrittlement due to grain boundary segregation tends to occur. Therefore, it is desirable that the P content be 0.2% or less.
- S is an impurity element and is desirably as low as possible. If it exceeds 0.05%, the precipitation of fine sulfides increases and the workability deteriorates. Therefore, it is desirable that the S content be 0.05% or less.
- the N content is preferably set to 0.02% or less. ⁇ : 0.005% or less
- the amount of 0 is preferably set to 0.005% or less.
- Ti, Nb, V, o.Zr.Cr One or two or more types in total 0.01 to 0.2%
- Ti, Nb, V, Mo, Zr, and Cr are required for non-aging (and improved deep drawability) using strength adjustment or reduction of solid solution C and N by carbide formation. Add accordingly. These elements have no effect when the total added amount is less than 0.01%, and impair the workability such as ductility and deep drawability when the total added amount exceeds 0.2%. Therefore, when adding Ti, Nb, V, Mo, Zr, and Cr, the total amount of these should be 0.01 to 2%.
- Ca.B 1 or 2 types or more, 0.005% or less in total
- Ca and B are effective elements that can improve the workability of a thin steel sheet, and are preferably added. However, if the total content of Ca and B exceeds 0.005%, the deep drawability is impaired. Therefore, when Ca and B are added, the total amount of these should be 0.005% or less.
- the finishing temperature is less than (Acm Cementite that precipitates at the tenite grain boundary increases, and a uniform pearlite structure cannot be obtained, resulting in a non-uniform structure.
- finish rolling is performed at a finishing temperature (Ar 3 transformation point ⁇ 20) or higher.
- the structure can be made uniform and the structure can be made finer in the subsequent steps, and workability such as improved hardenability, improved spheroidization rate of cold-rolled steel sheets and improved stretch flangeability can be achieved. Improvement can be achieved.
- rapid cooling after rolling is necessary in order to refine the structure of the ferrite crystal grains and pearlite after transformation and to make the material uniform.
- the cooling method is slow cooling, the structure becomes coarse, and the high-C steel does not have a uniform pearlite structure, resulting in a non-uniform structure.
- the cooling rate is 120 / sec or less, the structure such as ferrite crystal grains and pearlite generated by the transformation becomes coarse, and in the hypereutectoid steel, the cementite precipitates, resulting in an uneven structure.
- Cooling end temperature 500 ⁇ 800
- the cooling end temperature As for the cooling end temperature, if the temperature is rapidly cooled to a low temperature range of less than 500, the difference (margin allowance) from the winding temperature becomes small, and it becomes difficult to make the temperature uniform. In addition, additional cooling equipment for quenching is required, which increases equipment costs. Conversely, when the cooling end temperature exceeds 800, only a part of the structure is transformed and the structure becomes non-uniform, and the structure is coarsened by the subsequent cooling (gradual cooling) accompanying the winding temperature control.
- the steel strip is primarily cooled at a cooling rate of more than 120 Vsec to a temperature of 500 to 80 (T)
- precipitates such as ferrite grains and pearlite after transformation can be refined.
- the upper limit of the cooling rate is not specified, but the limit is about 2000 ° C / sec, which is industrially possible.
- the steel strip After secondary cooling, the steel strip must be wound at a winding temperature of 400 to 750 ° C. This is because if the winding temperature is lower than 400 ° C, a low-temperature transformation phase is generated, and if the temperature exceeds 750 ° C, the structure such as crystal grains becomes coarse and the workability deteriorates.
- the basic production conditions of the present invention are as described above. Manufacturing conditions can be used.
- the continuous green slab can be subjected to rough rolling by direct hot rolling or before being cooled to room temperature, charged into a heating furnace and reheated at 1200 to the following temperature.
- the rough rolling is directly started by rolling without cooling the continuous production slab to room temperature, or the rough rolling is started after heating to 1200 or less.
- the slab temperature before rolling can be made uniform, and the mechanical properties in the coil can be made more uniform.
- the material to be rolled can be heated by an induction heating device immediately before or during the finish rolling. According to the present invention, the temperature of the material to be rolled during rolling can be made more uniform, and the mechanical properties in the coil can be made more uniform.
- quenching After finish rolling, quenching can be started within a time period exceeding O.lsec and less than l.Osec.
- precipitates such as ferrite crystal grains and pearlite after transformation can be made finer, and workability can be further improved.
- the thin steel sheet manufactured by the above method for manufacturing a thin steel sheet can be further cold-rolled and annealed.
- the material and structure of the hot-rolled coil are uniform, if it is annealed after cold-rolling, a cold-rolled steel sheet having excellent workability and uniformity of mechanical properties can be obtained.
- the fluctuation (maximum value and minimum value) of the tensile strength in the width direction and the longitudinal direction of the hot-rolled steel strip is applied.
- a thin steel sheet characterized by being within ⁇ 8% of the average value of strength can be obtained.
- the variation in press workability (spring back during bending, etc.) within the coil is small. Consumers can also improve product yield and shape accuracy after press processing, and have excellent performance as a material.
- the steel composition is not particularly limited, and a conventional hot rolled steel sheet / cold rolled steel sheet having various characteristic levels can be applied.
- the present invention can be applied not only to a simple carbon steel sheet but also to a steel sheet containing special elements such as Ti, Nb, V, Mo, Zr, Ca, and B.
- special elements such as Ti, Nb, V, Mo, Zr, Ca, and B.
- the slab temperature before rolling can be made uniform, and the mechanical properties in the coil become even more uniform.
- the temperature of the material to be rolled during rolling can be made more uniform. Further, the mechanical properties in the coil can be made more uniform.
- the rolling reduction of the final rolling pass be 8% or more and less than 30%. This is because the reduction rate should be 8% or more in order to sufficiently reduce the size of austenite grains, and it should be 30% or more in order to maintain a good shape of the steel sheet. by. From the viewpoint of reducing the grain size of the hot-rolled steel sheet, it is desirable that the rolling reduction be more than 10% for each rolling pass.
- the finishing temperature when the C content is 0.8% or less, if the finish rolling is preferably performed at (Ar 3 transformation point -20) to (Ar 3 transformation point + 50) ° C, immediately after the finish rolling, Crystal grains before cooling the run-out can be refined.
- the finishing temperature By setting the finishing temperature to (Ar 3 transformation point +50) or less, coarsening of austenite grains is prevented, and ferrite grains after rolling are easily made fine.
- the crystal grains can be refined in the subsequent steps, and the strength-ductility balance and stretch flangeability can be improved, and further, the workability can be improved by increasing the r-value of the cold-rolled steel sheet.
- finish rolling is performed at a finishing temperature of (Acm transformation point -20) to (Acm transformation point + 100) ° C. If it is the same as the case of 8% or less, a thin steel sheet having excellent workability and uniform mechanical properties can be obtained. Finish By setting the temperature to (Acm transformation point +100) ° C or less, coarsening of austenite grains can be prevented and the pearlite core after rolling can be refined.
- the finishing temperature varies depending on the position of the material to be rolled in the width direction, the longitudinal direction, and the like. If the difference is large, the structure of the steel strip becomes non-uniform, so that the difference in the finishing temperature can be reduced. desirable. If the finish rolling is performed so that the difference in finishing temperature within the material to be rolled is within 50, the structure in the steel strip immediately after finish rolling can be made uniform, and the mechanical properties after winding into a coil can be made uniform. I can do it. As a result, the difference in the structure and the material of the final product can be ignored, so that the difference in the finishing temperature in the material to be rolled is preferably set to 50T: or less.
- the rapid cooling and the slow cooling are referred to as primary cooling and secondary cooling.
- the workability can be improved by the refinement of ferrite grains and pearlite after transformation.
- cooling at a cooling rate of 200 ° C / sec or more, more preferably 40 (TC / sec or more from the viewpoint of refining the ferrite crystal grains and refining the pearlite structure, cooling at a cooling rate of 200 ° C / sec or more, more preferably 40 (TC / sec or more, The upper limit of the cooling rate is not particularly specified, but is industrially limited to about 200 (TC / sec).
- the above-mentioned quenching stop temperature should be within the range of the present invention, and the temperature fluctuation in the coil width direction and the longitudinal direction after the quenching. (Highest value-lowest value) should be within 60 ° C. More preferably, the above-mentioned performance at the consumer can be remarkably improved by controlling the fluctuation of the tensile strength to within ⁇ . In this case, the variation in the material can be narrowed in this way by keeping the rapid cooling stop temperature fluctuation within 40 or less.
- the fluctuation of the above-mentioned rapid cooling stop temperature should be within 20 ° C. Reduction of material fluctuations is due to these temperature and tensile strength fluctuations. Can be determined from the relationship.
- the temperature in the coil width direction indicates a range excluding 30MI from both edges of the coil width in consideration of the measurement method of the temperature sensor.
- the quenching (primary cooling) capacity by performing cooling with a heat transfer coefficient of 2000 kcal / ni 2 h ° C, the above-mentioned fluctuation in temperature after quenching can be reduced.
- a preferred heat transfer coefficient is 5000 kcal / m 2 h ° C or more, and a more preferred level is SOOOkcal / n ⁇ .
- the primary cooling if the cooling is started within 0.1 lsec and less than l.Osec after finish rolling, precipitates such as ferrite crystal grains and perlite after transformation can be made finer. The workability can be further improved. Furthermore, in order to make the variation in the material of the hot-rolled steel strip a more preferable level, it is desirable that the start of cooling be more than 0.5 sec after finish rolling.
- the primary cooling After the primary cooling, it is desirable to perform slow cooling (secondary cooling) to adjust the winding temperature.
- second cooling slow cooling
- the cooling rate of the secondary cooling is less than 6 (TC / sec)
- high-precision temperature control becomes possible
- the cooling end temperature that is, the winding temperature becomes uniform. Since the structure of the steel strip can be made more uniform, it is preferable that the steel strip be subjected to secondary cooling at a cooling rate of less than 60 tVsec in order to make the mechanical properties in the coil uniform.
- the steel strip After secondary cooling, it is necessary to wind the steel strip at a winding temperature of 400 to 750.However, if it is less than 400, a low-temperature transformation phase is generated, and if it exceeds 750, the structure such as crystal grains becomes coarse. This is because workability deteriorates. It is desirable that the winding temperature of the high C material be 450 or more in order to prevent the formation of a low-temperature transformation phase. Also, from the viewpoint of making the material of the final product uniform, it is desirable that the difference in the coiling temperature within the coil be within 80 ° C.
- the present invention can also be applied to a direct rolling process in which a slab after continuous production is directly hot-rolled without passing through a heating furnace. It is also effective for a continuous rolling process using a coil box or the like. Further, when the material to be rolled is heated by the induction heating device immediately before or during finish rolling, it is effective to perform edge heating. If the obtained hot-rolled coil is annealed after cold-rolling, a cold-rolled steel sheet having excellent workability and uniformity of mechanical properties can be obtained. At this time, annealing is more preferably performed by continuous annealing in order to achieve uniform mechanical properties.
- Example 1 Example 1
- Tensile test specimens were taken from five locations in the longitudinal direction of the hot-rolled coil, and the average tensile strength (TS), total elongation (El), variation in tensile strength (ATS), and variation in total elongation ( ⁇ E l) was measured.
- TS average tensile strength
- El total elongation
- ATS variation in tensile strength
- ⁇ E l variation in total elongation
- the hole expansion ratio ( ⁇ ) and its variation ( ⁇ ) were measured in order to evaluate the stretch flangeability.
- the sheet was cold-rolled to a thickness of 0.8 IM, continuously annealed, and the r-value was evaluated to evaluate deep drawability.
- Table 3 shows the measurement results of the mechanical properties of these hot-rolled coils and cold-rolled annealed sheets.
- ⁇ TS and ⁇ E1 are respectively 1/2 of the difference between the maximum value and the minimum value of TS and E1.
- the tensile properties were investigated using samples taken from positions excluding both edges 30I1 in the coil width direction and 5 m each at both ends in the coil longitudinal direction, and the average value of all values was taken as the average value in the coil.
- the mechanical examples of the present invention are more mechanical in all the component systems. Variation in properties ATS, ⁇ El are small.
- the steel sheets Nos. 23 to 28 of the comparative examples one or more of the manufacturing conditions specified in the present invention were not satisfied, and the steel sheets No. 15-2.2 of the present invention examples having the same chemical components were not satisfied. However, the uniformity of mechanical properties or workability is poor.
- the variation in the rapid cooling (primary cooling) stop temperature in the coil is smaller than that of the conventional method using laminar cooling, and the variation in mechanical properties is reduced to a more desirable level.
- the cooling method in the present invention is a multi-jet type cooling method having a high heat transfer coefficient.
- the present inventors have conducted intensive studies to improve the stretch-flange property, elongation at break, and impact resistance of a high-tensile steel material manufactured by reheating a continuous green slab or directly hot rolling. Was done.
- the elongation-flangeability and elongation at break are affected by the presence of a band structure in which C, Mn, etc. are concentrated at the center of the sheet thickness, and the yield strength of the material is required to improve the impact resistance. It has been found that it is effective to increase the workability without impairing it.
- Mass% characterized by comprising the following steps: C: 0.05 to 0.14%, S i: 0.5% or less, Mn: 0.5 to 2.5%, P : 0.05% or less, S: 0.01% or less, ⁇ : 0.005% or less, and Ca: less than 0.0005%.
- a step of manufacturing a slab by a continuous structure that performs a segregation reduction treatment (1) A step of manufacturing a slab by a continuous structure that performs a segregation reduction treatment.
- Mass% characterized by having the following processes: C: 0.05-0.14%, S i: 0.5% or less, Mn: 0.5-2.5%, P : 0.005% or less, S: 0.01% or less, :: 0.005% or less, and Ca: less than 0.0005%.
- a step of manufacturing a slab by a continuous structure for performing a segregation reduction treatment (1) A step of manufacturing a slab by a continuous structure for performing a segregation reduction treatment.
- Si is a solid solution strengthening element and is added to strengthen the steel sheet. However, if it exceeds 0.5%, the surface properties deteriorate, so the content is set to 0.5% or less.
- Mn is added in an amount of 0.5% or more to improve the toughness of the steel sheet and improve the strength by solid solution strengthening. If it exceeds 2.5%, the workability will be significantly deteriorated, so the content should be 0.5% or more and 2.5% or less.
- P has the effect of solid solution strengthening the steel sheet. However, if the content exceeds 0.05%, the workability is degraded due to segregation, so the content of P is set to 0.05% or less.
- S forms sulfides, and if it exceeds 0.01%, the amount increases and the workability deteriorates. Therefore, the content of S is set to 0.01% or less.
- ⁇ suppresses cracking on the slab surface or under the slab surface during continuous fabrication Therefore, its content is restricted to 0.005% or less.
- alumina oxide which is a deoxidation product when A1 is used for deoxidation at the time of smelting, is a low melting point A1-Ca- ⁇ -based oxide. Since A1-Ca-0 oxides expand during hot rolling and deteriorate workability (elongation-flangeability), Ca is treated as an unavoidable impurity in the present invention. Regulate to less than 0.0005%, which is the level of no additives. .
- the above is the basic component composition, but one or more of Ti, Nb, V, Mo, Zr, and Cr can be added to further improve the characteristics.
- one or more of Ti, Nb, V, Mo, Zr, and Cr can be added in a total amount of 0.01% to 0.3%.
- elements other than those described above may be contained as long as the function and effect are not impaired.
- the reheating temperature is 1250 ° C or less.
- the finishing temperature of the finish rolling mill is set to Ar 3 or more, and the ferrite crystal grain size after transformation and pearlite are refined to improve stretch-flange property and impact resistance.
- Cooling in the runner-out after hot rolling is performed after finish rolling to refine the ferrite crystal grain size and pearlite after transformation, and to improve the impact resistance due to excellent workability and high yield strength. Start within 2 seconds, more preferably within 1 second.
- Figure 1 shows the effect of primary cooling start time on mechanical properties. If cooling is started within 2 seconds after finish rolling, excellent workability and high strength can be obtained.
- the cooling rate of the primary cooling is specified in order to improve the elongation-flangeability by miniaturizing the ferrite crystal grain size and pearlite after transformation and suppressing the band structure at the center of the sheet thickness.
- the band structure corresponds to the concentration of C and Mn in the solidification stage.
- the transformation temperature from austenite to ferrite is low. Due to the slow transformation, a large amount of pearlite is formed, deteriorating the elongation and flangeability.
- the cooling rate is set to 100 ° C / s or more, the ferrite transformation becomes easy even in the C and Mn enriched parts, and as a result, the elements are homogenized and the band structure is suppressed.
- the cooling rate is out of the range of the present invention, a band structure is observed, and the crystal grain size is larger than that of the microstructure according to the method of the present invention.
- the cooling rate is more preferably 200 ° CZs or more, and more preferably 400 ° CZs or more in order to further improve the workability, from the viewpoints of ferrite crystal grain size and pearlite miniaturization.
- the end temperature of primary cooling is more than 750, it will be difficult to refine the ferrite, and if it is less than 600 ° C, the second phase will be a hard low-temperature transformation phase. Less than
- Secondary cooling is performed. Secondary cooling may be started immediately after primary cooling is stopped, or may be started after cooling for a while, and is not specified. Secondary cooling cold The rejection rate should be 50 ° C / s or less in order to properly transform the austenitic structure into pearlite and achieve excellent workability.
- the winding temperature When the winding temperature is higher than 65 ° C., coarse pearlite which is harmful to ductility is generated, and when the winding temperature is lower than 450 ° C., a structure mainly composed of a low-temperature transformation phase is formed and workability is deteriorated. It shall be 450 ° C or more and 65 0 ° C or less. If more uniform mechanical properties are desired, it is desirable to keep the temperature difference within the coil within 5 O: by using cooling equipment with excellent cooling controllability.
- the effect is not impaired. Further, the effects of the present invention are not impaired even as a hot-dip and cold-rolled base material for hot-dip galvanizing.
- the present invention it is possible to obtain more uniform mechanical properties by heating the widthwise edge portion by an induction heating device or the like after rough rolling, before finishing rolling, or between finishing rolling stands. Becomes Further, the effect of the present invention is not impaired in continuous hot rolling in which the rough rolling bar is welded after the rough rolling and the finish rolling is continuously performed.
- Materials Nos. 1 to 4 of the present invention example satisfying the chemical components of the present invention and the production conditions are materials which are comparative examples when any one of the production conditions is out of the scope of the present invention. Compared with, it is clear that the workability (strength-hole expansion balance) is excellent, the yield strength is high, and the impact resistance is excellent.
- FIG. 2 also shows the tensile strength and the hole expansion ratio of the present invention example and the comparative example. It is clear that excellent characteristics can be obtained by the present invention. 6
- the present inventors studied in detail the composition of the components, the rolling conditions, and the cooling conditions after rolling, and found that the stabilization of the strength characteristics was particularly affected by the cooling conditions after rolling. What was done. That is, the present invention
- a method for producing a high-strength thin steel sheet comprising: rolling within 6 seconds after the end of rolling, cooling at an average cooling rate of 80: / s or more, and exceeding 500 to 700 ° C or less.
- the content is set to 0.03% or more and 0.12% or less. .
- Si is added to promote the precipitation of ferrite and prevent YS from rising excessively. If added over 1%, the weldability will deteriorate, so it should be 1% or less.
- Mn is added to solid-solution strengthen steel, improve hardenability, and improve strength. If it is less than 0.5%, the effect cannot be obtained, and if it exceeds 2%, the toughness is deteriorated due to the increase in weldability and low-temperature transformation phase, so the content is made 0.5% or more and 2% or less.
- P is set to 0.02% or less and S is set to 0.01% or less.
- Nb, V, Ti, and Mo are added to improve the strength.
- Nb, V, and Ti are precipitation hardening elements that refine the structure of the hot-rolled steel sheet and improve its strength. Add 005% or more for each of these effects. Excessive addition saturates the effect and degrades weldability, and increases the low-temperature transformation phase, thereby deteriorating toughness. Therefore, the upper limit is 0.1%.
- Mo improves hardenability, strengthens the structure, and improves strength. To obtain this effect, 0.05% or more is added. Excessive addition increases the weldability and low-temperature transformation phase and deteriorates the toughness of the steel sheet.
- elements other than those described above may be contained as long as the function and effect are not impaired.
- Al, Cu, Ni, B, Ca, etc. 1% or less, Cu, ⁇ 0. 0% or less, ⁇ , ⁇ . 3 is permitted to contain 0.005% or less.
- rolling is performed at 1070 or less with a cumulative rolling reduction of 30% or more.
- Cooling starts within 6 seconds after the end of rolling in order to refine crystal grains and stabilize strength and toughness. In order to improve the strength and the viscous property by the effect of grain refinement, it is preferably within 3 seconds.
- Cooling rate is the most important factor in the present invention. In order to prevent coarse grains and to obtain uniform fine crystal grains, rapid cooling is used, and the average cooling rate is set to 8 (TCZs or more. More preferably, the average cooling rate is set to 100 ° CZs or more.
- the cooling stop temperature When the cooling stop temperature is low, the low-temperature transformation phase increases, YS rises significantly, and YR exceeds The temperature rises more than 500 degrees Celsius as the temperature increases and the toughness deteriorates. On the other hand, if the temperature exceeds 700 ° C, strength stability cannot be obtained. Therefore, the cooling stop temperature is set to exceed 500 ° C and 700 ° C or less.
- the steps after the rapid cooling is stopped are not particularly defined.
- a coil is formed by winding, it is slowly cooled by air cooling or run-out cooling and wound according to a standard method.
- the slow cooling reduces the low-temperature transformation phase and suppresses the excessive rise of YS, which has a more preferable effect.
- the temperature be 40 t: Zs or less.
- the rough bar is heated by an induction heating device provided on the entrance side of the finishing rolling mill or between the stands of the continuous hot rolling finishing mill, and between the stands of the continuous hot rolling finishing rolling mill or the finishing rolling mill.
- Heating the edge of the coarse bar in the width direction with an induction heating device in the pre-process to make the temperature distribution uniform in the width direction makes the mechanical properties more uniform, and there is no problem.
- the present invention to a continuous hot rolling process using a coil pox, there is no problem in performing heating of the coarse bar before and after the coil box and before and after the rough rolling mill, or after the coil box and before and after the welding machine. There is no.
- 1 and 6 are comparative examples in which the primary cooling stop temperature is out of the range of more than 50,000 to 700 ° C. which is the range of the present invention.
- the production conditions of 2 to 5 vary the primary cooling stop temperature within the range of the present invention, and are examples of the present invention.
- All specimens were 7 mm thick and Table 10 shows the results of the mechanical tests.
- Figures 3 to 7 show the mechanical test results shown in Table 10.
- the primary cooling rate was 150 ° CZ sec and the secondary cooling rate was 3 ° C / sec.
- rapid cooling means primary cooling.
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Description
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EP00962863.7A EP1143019B1 (en) | 1999-09-29 | 2000-09-27 | Method for manufacturing a coiled steel sheet |
US09/837,435 US6652670B2 (en) | 1999-09-29 | 2001-04-18 | Steel sheet and method for manufacturing the same |
US10/448,697 US20030196731A1 (en) | 1999-09-29 | 2003-05-30 | Method for manufacturing a steel sheet |
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JP11/275955 | 1999-09-29 | ||
JP27595599 | 1999-09-29 | ||
JP2000/60282 | 2000-03-06 | ||
JP2000060282A JP3864663B2 (ja) | 2000-03-06 | 2000-03-06 | 高強度薄鋼板の製造方法 |
JP2000/119887 | 2000-04-20 | ||
JP2000119887A JP2001303129A (ja) | 2000-04-20 | 2000-04-20 | 高張力薄鋼板の製造方法 |
JP2000/180903 | 2000-06-16 | ||
JP2000180903 | 2000-06-16 | ||
JP2000/268894 | 2000-09-05 | ||
JP2000268894A JP3879381B2 (ja) | 1999-09-29 | 2000-09-05 | 薄鋼板および薄鋼板の製造方法 |
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- 2000-09-27 EP EP00962863.7A patent/EP1143019B1/en not_active Revoked
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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EP1277846A1 (en) * | 2001-06-28 | 2003-01-22 | Kabushiki Kaisha Kobe Seiko Sho | High-carbon steel wire rod with superior drawability and method for production thereof |
US6783609B2 (en) | 2001-06-28 | 2004-08-31 | Kabushiki Kaisha Kobe Seiko Sho | High-carbon steel wire rod with superior drawability and method for production thereof |
WO2004003247A1 (en) * | 2002-06-28 | 2004-01-08 | Posco | Super formable high strength steel sheet and method of manufacturing thereof |
US7806998B2 (en) | 2002-06-28 | 2010-10-05 | Posco | Method of manufacturing super formable high strength steel sheet |
CN114574685A (zh) * | 2020-11-30 | 2022-06-03 | 宝山钢铁股份有限公司 | 一种短流程连铸连轧普碳钢热轧带钢表面及力学性能调控方法 |
CN114574685B (zh) * | 2020-11-30 | 2024-04-05 | 宝山钢铁股份有限公司 | 一种短流程连铸连轧普碳钢热轧带钢表面及力学性能调控方法 |
Also Published As
Publication number | Publication date |
---|---|
US20010050119A1 (en) | 2001-12-13 |
KR100401272B1 (ko) | 2003-10-17 |
KR20010074870A (ko) | 2001-08-09 |
US20030196731A1 (en) | 2003-10-23 |
EP1143019A4 (en) | 2008-04-30 |
EP1143019A1 (en) | 2001-10-10 |
EP1143019B1 (en) | 2014-11-26 |
US6652670B2 (en) | 2003-11-25 |
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