EP2003221B1 - Hard extra-thin steel sheet and method for manufacturing the same - Google Patents
Hard extra-thin steel sheet and method for manufacturing the same Download PDFInfo
- Publication number
- EP2003221B1 EP2003221B1 EP07741011.6A EP07741011A EP2003221B1 EP 2003221 B1 EP2003221 B1 EP 2003221B1 EP 07741011 A EP07741011 A EP 07741011A EP 2003221 B1 EP2003221 B1 EP 2003221B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- steel sheet
- phase
- less
- thin steel
- average
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 229910000831 Steel Inorganic materials 0.000 title claims description 144
- 239000010959 steel Substances 0.000 title claims description 144
- 238000004519 manufacturing process Methods 0.000 title claims description 33
- 238000000034 method Methods 0.000 title description 27
- 229910000765 intermetallic Inorganic materials 0.000 claims description 31
- 238000005121 nitriding Methods 0.000 claims description 29
- 238000005096 rolling process Methods 0.000 claims description 27
- 150000004767 nitrides Chemical class 0.000 claims description 25
- 229910052719 titanium Inorganic materials 0.000 claims description 25
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims description 24
- 238000005098 hot rolling Methods 0.000 claims description 22
- 238000001816 cooling Methods 0.000 claims description 21
- 229910052758 niobium Inorganic materials 0.000 claims description 20
- 150000001875 compounds Chemical class 0.000 claims description 19
- 238000009864 tensile test Methods 0.000 claims description 18
- 238000005097 cold rolling Methods 0.000 claims description 17
- 239000010410 layer Substances 0.000 claims description 17
- 238000000137 annealing Methods 0.000 claims description 16
- 229910052742 iron Inorganic materials 0.000 claims description 16
- 229910052782 aluminium Inorganic materials 0.000 claims description 15
- 229910052748 manganese Inorganic materials 0.000 claims description 15
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 15
- 229910052710 silicon Inorganic materials 0.000 claims description 15
- 239000002344 surface layer Substances 0.000 claims description 15
- 238000001953 recrystallisation Methods 0.000 claims description 14
- 229910052804 chromium Inorganic materials 0.000 claims description 12
- 238000005255 carburizing Methods 0.000 claims description 11
- 229910000859 α-Fe Inorganic materials 0.000 claims description 9
- 239000006185 dispersion Substances 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- 229910052796 boron Inorganic materials 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 239000002131 composite material Substances 0.000 claims description 4
- 229910052718 tin Inorganic materials 0.000 claims description 3
- 229910052787 antimony Inorganic materials 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- 229910052715 tantalum Inorganic materials 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims 1
- 230000000694 effects Effects 0.000 description 49
- 239000000463 material Substances 0.000 description 35
- 239000011159 matrix material Substances 0.000 description 13
- 230000006866 deterioration Effects 0.000 description 9
- 238000004534 enameling Methods 0.000 description 9
- 239000007789 gas Substances 0.000 description 9
- 238000005266 casting Methods 0.000 description 7
- 150000001247 metal acetylides Chemical class 0.000 description 7
- 150000003568 thioethers Chemical class 0.000 description 7
- 229910001005 Ni3Al Inorganic materials 0.000 description 6
- 238000004381 surface treatment Methods 0.000 description 6
- 238000005336 cracking Methods 0.000 description 5
- 230000001747 exhibiting effect Effects 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000005482 strain hardening Methods 0.000 description 5
- 230000007547 defect Effects 0.000 description 4
- 230000002542 deteriorative effect Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000004566 building material Substances 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 238000005868 electrolysis reaction Methods 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000000877 morphologic effect Effects 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910000943 NiAl Inorganic materials 0.000 description 1
- -1 REM compound Chemical class 0.000 description 1
- NPXOKRUENSOPAO-UHFFFAOYSA-N Raney nickel Chemical compound [Al].[Ni] NPXOKRUENSOPAO-UHFFFAOYSA-N 0.000 description 1
- 229910010038 TiAl Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 238000010409 ironing Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000006396 nitration reaction Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000004451 qualitative analysis Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000012360 testing method Methods 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
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/06—Surface hardening
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—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
- C21D8/0457—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 with diffusion of elements, e.g. decarburising, nitriding
-
- 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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
-
- 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
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
-
- 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
- C21D2201/00—Treatment for obtaining particular effects
- C21D2201/05—Grain orientation
-
- 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
- C21D2211/004—Dispersions; Precipitations
-
- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0436—Cold rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—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
- C21D8/0442—Flattening; Dressing; Flexing
Definitions
- the present invention relates to a thin steel sheet having a sheet thickness of 0.400 mm or less which also includes a surface treated steel sheet used for electric equipments, electronic parts, building materials and metallic containers, and to a method of manufacturing the same.
- a thin steel sheet having a sheet thickness of 0.400 mm or less has been used for various purposes such as for electric equipments, electronic parts, building materials and metallic containers, and a process of making a steel sheet more thin has been carried out to lower the cost of raw material.
- a member employing such material accordingly causes decrease in its strength, and thus hardening of material is also generally required at the time of thinning the material.
- One of obvious problem occurring in such an extra thin and hard material is deterioration in formability.
- a thin material immediately causes breakage when constriction is occurred, and thus it is extremely important to give a uniform deformation.
- a tensile test which is generally applied for evaluating characteristics of a steel sheet, it means that a sheet has to be hardened without turning down a uniform elongation.
- a steel sheet for containers for which a heavy working such as drawing, ironing or tensile elongation is performed methods disclosed in Patent Documents 1 to 3 or the like have been proposed to assure the formability.
- An object of the present invention is to prevent breakage or constriction caused by lack of uniform deformation, which is a problem occurring upon using an extra thin, hard material.
- an object is to, for deterioration in elongation due to a hardening of material, consider the deterioration of local elongation on a priority basis so as to assure a uniform elongation and to prevent a local deformation (constriction) up to a high strained region even for the same total elongation.
- another object of the present invention is to make clear a material condition, and to provide a steel sheet employing such the condition and a manufacturing method thereof.
- the present inventors have carried out a research on dispersing various second phases in a steel sheet for hardening the steel sheet.
- it belongs to a category of precipitation hardening and transformation hardening, and a material can be hardened by dispersing a second phase, according to which, of course, the formability deteriorates.
- the inventors found out that when a second phase having a specific morphology is dispersed in a steel sheet, hardening is achieved while preventing deterioration in uniform elongation.
- the inventors have in detail investigated morphology, amount and kind of second phase and also scopes of steel sheet materials for obtaining preferable properties, and thus completed the present invention. Key points of the present invention are as shown below.
- a sign '*' in this specification represents multiplication (x).
- the present invention relates to a thin steel sheet having a sheet thickness of 0.400 mm or less and a manufacturing method thereof.
- a hot rolling condition is limited thereby controlling the morphology of oxide.
- inclusion of oxide in a thin steel sheet as for the present invention is controlled because it is an extremely unfavorable substance. This is because deformation concentrated around the oxide gives highly sensitive effect in breaking a base material as the base material itself is thin.
- a good example can be shown by flange formability in a process of manufacturing cans.
- an oxide amount is strictly controlled and its production is given at a very low level.
- An adverse effect of oxide on a thin material does not just stay on as the oxide problem, and when a rolled and elongated oxide as in an enameling steel sheet cracks in a cold rolling process and forms voids therearound, those voids give a cutting effect, thereby causing a further deterioration in formability of the base material.
- an oxide is temporarily rolled and elongated at a hot rolling step but the oxide cracks in the following cold rolling step thereby forming many voids around the cracked oxide. All oxides in an end product are finely cracked and are in an isotropic form.
- the oxide has to be a rolled and elongated oxide at a final stage, and thus a hot rolling step is employed as a way for this.
- a hot rolling step is employed as a way for this.
- an oxide rolled and elongated under hot rolling is still kept as a rolled and elongated oxide even after the cold rolling and annealing, and an anisotropic form is necessarily maintained to an end product.
- this difference may be fundamentally exhibited by difference in the composition of oxides.
- a compounded form of relatively soft Mn-containing oxide with hard Nb-, B-containing oxide works preferably in accelerating cracking.
- oxide be provided as a homogeneous substance and not as a compounded product including oxides of different composition, so as to give a uniform deformation at the time of cold rolling and avoid cracking.
- the steel of the present invention is invented on the basis of new findings such as when an oxide is rolled and elongated to a specific form and maintained as it is, a work hardening behavior thereof dramatically changes, and when a local deformation is strongly controlled, it well acts on a practical elongation capacity even in the case of a thin steel sheet.
- a hard, extra thin material exhibiting more uniform elongation capacity up to a high strained region while preventing a local deformation (constriction) from occurring, even if the same strength and the same total elongation are employed, can be obtained.
- a thin material is used, such as breakage due to a lack of uniform deformation and a generation of constriction.
- FIG. 1 is a diagram showing a region in a thickness direction of a hard extra-thin steel sheet of the present invention.
- the C amount is set to 0.800% or less to avoid deterioration in formability.
- the amount is preferably 0.100% or less, more preferably 0.060% or less.
- the amount is preferably from 0.0050 to 0.040%, more preferably from 0.0080 to 0.030%.
- the content of C to be needed from the viewpoint of assuring the strength or the like may be low.
- the required strength can still be achieved at the C content of 0.0050% or less.
- the content of 0.0030% or less, as well as 0.0015% or less can also be employed. From the point of maintaining high drawability by improving an r value, it is preferable for the C amount to be small.
- the N amount is also set to 0.800% or less or 0.600% or less to avoid deterioration in formability.
- the amount is preferably 0.100% or less, more preferably 0.060% or less.
- the amount is preferably from 0.0050 to 0.040%, more preferably from 0.0080 to 0.030%.
- the content of N to be needed from the viewpoint of assuring the strength or the like may be low.
- the required strength can still be achieved at the N content of 0.0050% or less.
- the content of 0.0030% or less, as well as 0.0015% or less can also be employed. From the point of maintaining high drawability by improving an r value, it is preferable for the N amount to be small.
- Si is set to 2.0% or less because at a too high content, formability or surface treatment property deteriorates.
- oxide when oxide is used as the second phase, remaining of oxygen in the steel may become difficult or a rolled and elongated oxide which being the preferred characteristic for the present invention may be hardly obtained, as described later.
- the Si content when carburization or nitriding is carried out for forming the second phase, there may be a case where C or N entered in the steel forms coarse Si carbide or Si nitride in a crystalline grain boundary and thus causing brittle cracks.
- the Si content may have to be 1.5% or less, further 1.0% or less.
- the Si amount it is preferable for the Si amount to be small.
- the formability can be improved by setting the content to be 0.5% or less, further 0.1% or less, or even further 0.07% or less.
- Mn is set to 2.0% or less because at a too high content, formability or surface treatment property deteriorates. Meanwhile, in the steel of the present invention, when oxide is used as the second phase, as described later, a rolled and elongated oxide which is preferable for the present invention is readily obtained. In addition, when sulfide is used for forming the second phase, a rolled and elongated sulfide can be readily obtained, and thus this element is useful. Consequently, a preferred range of Mn is from 0.05 to 1.0%, preferably from 0.15 to 0.8%, and even more preferably from 0.25 to 0.7%.
- P is set to 0.10% or less because at a too high content, not only the formability deteriorates, but also when carburization or nitriding are performed for forming the second phase, the carburization property or nitriding property of the steel sheet is obstructed. From the point of maintaining high formability, it is preferable for the P amount to be small.
- the formability can be improved by setting the content to be 0.05% or less, further 0.01% or less.
- S is set to 0.100% or less or otherwise deteriorates heat-rolling ductility and becomes the cause of obstructing the casting or hot rolling.
- Mn, Cu, TI, REM or the like when a large amount of Mn, Cu, TI, REM or the like is added and a sulfide thereof is used as the second phase that is needed for the present invention, deterioration in hot-rolling ductility is small and thus this element is useful. Consequently, a preferred range of S is from 0.015 to 0.080%, preferably from 0.025 to 0.070%, and even more preferably from 0.035 to 0.060%.
- Al is set to 3.0% or less because at a high content, there may be a problem such as casting becomes difficult or defects on the surface increase.
- the A1 content may sometimes have to be 0.010% or less, further 0.005% or less, even further 0.002% or less, or particularly further 0.001% or less.
- Al may serve as an element of forming an intermetallic compound such as Ni 3 Al, and exhibits a preferable effect on the dispersion of the second phase needed for the present invention.
- the content may vary depending on the kind or amount of metallic element forming a compound together with Al, but in this case, the Al content is preferably 1.0% or more, further 1.5% or more, even further 2.0% or more.
- O is preferably set to 0.010% or less when an oxide is not used as the second phase that provides the characteristic of the present invention because deoxidation via Al, Si, Ti or the like occurs. It is set so because when oxide in the steel becomes an isotropic form (spherical) which gives no effect for exhibiting advantages of the present invention, this element readily becomes the cause of cracking. Even in the case where an oxide is used as a useful second phase, excessive oxide may readily become the cause of cracking, and thus the O content has to be set to 0.200% or less, preferably 0.010 to 0.100%, more preferably 0.020 to 0.080%, even more preferably 0.030 to 0.050%.
- Ti causes the increase of recrystallization temperature of the steel sheet, and significantly deteriorates passability of extra thin steel sheet subjected in the present invention in annealing. Therefore, the Ti content is set to be 4.00% or less.
- the content may be 0.04% or less, more preferably 0.01% or less.
- oxides, sulfides, carbides, nitrides and intermetallic compounds, of Ti can be used as the second phase that provides the characteristic of the present invention.
- the content may vary depending on the kind or amount of an element forming the compound, but a sufficient effect can be exhibited at a content of 0.06% or more. More preferred is 0.100% or more.
- Nb has the same effect as Ti that it causes the increase of recrystallization temperature, and significantly deteriorates passability of extra thin steel sheet subjected in the present invention in annealing. Therefore, the Nb content is set to be 4.00% or less.
- the content may be 0.04% or less, more preferably 0.01% or less.
- oxides, sulfides, carbides, nitrides and intermetallic compounds, of Nb can be used as the second phase that provides the characteristic of the present invention.
- the content may vary depending on the kind or amount of an element forming the compound, but a sufficient effect can be exhibited at a content of 0.06% or more. More preferred is 0.100% or more.
- REM also has the same effect as Ti and Nb, and as it is an expensive element, the content is set to be 4.00% or less.
- the content may be 0.04% or less, more preferably 0.01 % or less.
- oxides, sulfides, carbides, nitrides and intermetallic compounds, of REM can be used as the second phase that provides the characteristic of the present invention.
- the content may vary depending on the kind or amount of an element forming the compound, but a sufficient effect can be exhibited at a content of 0.06% or more. More preferred is 0.100% or more.
- B also has the same effect as Ti and Nb. However, its ability to form carbonitride is less than that of Ti or Nb although it may vary depending on the added amount.
- B is added simultaneously with those elements for the purpose of forming carbide or nitride as the second phase, it causes the increase of recrystallization temperature of the steel sheet, and significantly deteriorates passability of extra thin steel sheet subjected in the present invention in annealing. Therefore, B is useful in the case where Ti or Nb content is small.
- the upper limit is set to 0.0300% because an excessive amount results in notable cracks in a steel slab upon casting.
- the content may be 0.0020% or less, more preferably 0.0010% or less.
- oxides, sulfides, carbides, nitrides and intermetallic compounds, of B can be used as the second phase that provides the characteristic of the present invention.
- the content may vary depending on the kind or amount of an element forming the compound, but a sufficient effect can be exhibited at a content of 0.0040% or more. More preferred is 0.0100% or more.
- Cu is set to 8.00% or less because at a too high content, not only the recrystallization temperature significantly increases, but also defects in surface quality are occurred and formability or surface treatment property deteriorates.
- a metallic Cu phase, an intermetallic compound phase or the like can also be used as the second phase.
- a sulfide is used for forming the second phase, a rolled and elongated sulfide is readily obtained and thus this is element is useful. Consequently, a preferred range of Cu is from 0.10 to 4.00%, more preferably from 0.20 to 3.00%, even more preferably from 0.30 to 2.50%.
- Ca is a useful element for the steel of the present invention as when a sulfide is used as the second phase, a rolled and elongated sulfide can be readily obtained.
- Ca is usually hardly contained in a large amount in the steel due to high reactivity, and thus the amount is set to 1.00% or less.
- a preferred range is from 0.01 to 0.50%, more preferably from 0.05 to 0.30%.
- Ni is an expensive element, and its amount is set to 8.00% or less.
- Ni serves as an element of forming an intermetallic compound such as Ni 3 Al, and it exhibits a favorable effect for the dispersion of the second phase needed for the present invention.
- the amount may vary depending on the kind or amount of metallic element forming a compound together with Ni, but is preferably 1.0% or more, further 1.5% or more, even further 2.0% or more.
- Cr is also an expensive element, and its amount is set to 20.00% or less.
- the amount may be 0.06% or less, more preferably 0.02% or less.
- oxides, sulfides, carbides, nitrides and intermetallic compounds, of Cr can be used as the second phase that provides the characteristic of the present invention.
- the amount may vary depending on the kind or amount of an element forming the compound, but a sufficient effect can be exhibited at a content of 0.10% or more. More preferred is 0.50% or more, even more preferred is 1.5% or more, and further more preferred is 2.50% or more.
- the content of elements other than those mentioned above is not particularly limited, but Sn, Sb, Mo, Ta, V and W are added each by an amount of 0.10% or less which in total giving a sum of amounts of 0.50% or less, so as to impart properties not provided by the present invention. With this amount, the effect of the present invention is not interfered in any way. However, it is necessary to give an attention as there may be a case where those elements form a coarse compound having an isotropic form and thus deteriorating the formability.
- the amount of each element is preferably set to 0.010% or less and a sum of amounts of 0.050% or less, more preferably set to 0.0020% or less and a sum of amounts of 0.0050% or less, and even more preferably set to 0.0010% or less and a sum of amounts of 0.0030% or less.
- the observation method of the second phase is not particularly limited to those defined in the present invention.
- the morphology can be observed directly by a physical measuring equipment such as an electron microscope which allows the observation of micro regions.
- an observation can be made by a high-power optical microscope.
- an optical microscope or a scanning electron microscope (SEM) steel sheets a cross section of which is polished and further subjected to etching can be observed, and with a transmission electron microscope (TEM), a thin film as well as an extracted replica obtained by a SPEED method, or the like can be observed.
- SEM scanning electron microscope
- a residue in which a matrix is dissolved by an electrolysis extraction may also be observed.
- the observed second phase can be identified by EDX or electron beam diffraction patterns, but the technique is not limited to these and any analytical instrument currently providing a significantly improved performance may also be used. The point is that it is fine as long as a form, size and number density, or if necessary a kind, of the second phase can be determined according to an appropriate method. It is thought that there may be a case where a full identification is difficult in some kinds that provide a composition of various phases. However, since the effect of the present invention is achieved regardless of the kind by dispersing a second phase in a specific morphology, those difficult to be identified can also be included in the present invention.
- volume fraction and the number density when more fine nitrides are considered using more advanced analytical instrument, these values may be increased. However, the effect of the present invention still can be distinguished when a size of 0.02 ⁇ m or greater is used as an object with the use of a physical instrument of normal level.
- the present invention has a feature of containing 0.05% or more of the second phase observed as above, having an average major axis of 0.10 ⁇ m or greater and an average minor axis of 0.05 ⁇ m or greater and satisfying average major axis/average minor axis ⁇ 2.0.
- the size of average major axis is preferably 0.20 ⁇ m or greater, more preferably 0.50 ⁇ m or greater, even more preferably 1.00 ⁇ m or greater, even more preferably 2.00 ⁇ m or greater, even more preferably 5.00 ⁇ m or greater.
- a too large second phase it becomes the cause of breakage in an early stage of work thereby significantly deteriorating the ductility.
- the size is set preferably to 30 ⁇ m or less, more preferably to 20 ⁇ m or less.
- the average major axis/average minor axis is preferably 3.0 or more, more preferably 5.0 or more, even more preferably 8.0 or more.
- the volume fraction is preferably 0.1% or more, more preferably 0.3% or more, even more preferably 1.0% or more, even further preferably 2.0% or more.
- the fraction is set preferably to 20% or less, more preferably to 10% or less.
- the number density of the second phase 0.01 pieces/ ⁇ m 2 or more when a cross section of the steel sheet is observed and 0.001 pieces/ ⁇ m3 or more when a spatial dispersion is measured such as when a thin film is observed with extraction replica or transmission electron microscope, will exhibit a remarkable effects of the present invention.
- the number density is preferably 0.03 pieces/ ⁇ m 2 or more, more preferably 0.1 pieces/ ⁇ m 2 or more, even more preferably 0.3 pieces/ ⁇ m 2 or more.
- the number density is preferably 0.003 pieces/ ⁇ m3 or more, more preferably 0.01 pieces/ ⁇ m 3 or more, even more preferably 0.03 pieces/ ⁇ m 3 or more.
- the number density correlates with the above-mentioned size and volume fraction, and it is necessary to be careful not to extremely increase or decrease the density within the scope of not deteriorating the formability as in the size and volume fraction.
- the second phase in the present invention is harder than an Fe phase provided as a matrix, and thus a deformation of matrix occurs on a priority basis upon a deformation of steel sheet.
- the deformation of matrix is restricted by the second phase, work-hardening of the matrix becomes significant. Consequently, it is believed that the strain transmissibility improves and the deformation continues while being covered in a larger area thereby giving a higher uniform elongation.
- an anisotropic second phase is dispersed, it is believed that a restriction degree in the matrix becomes greater than that in a general isotropic second phase.
- the deformation of matrix that is a main phase making the most of the sheet by volume is definitely the reason for a uniform deformation in the steel of the present invention and not the second phase.
- the main phase is Fe; and a main phase in the present invention is supposed as a ferrite phase of Fe.
- Its volume fraction is preferably 80% or more.
- a pearlite, bainite or martensite is known as the phase mainly composed of Fe, but in the present invention, as strengthening the sheet is achieved by a dispersion of second phase, the main phase is preferably a soft and uniform phase from the viewpoint of formability.
- the volume fraction is preferably 85% or more, more preferably 90% or more, so as to avoid deterioration in elongation capacity due to a formation of second phase in excess.
- an orientation relationship of the second phase and the main phase is also an important matter.
- the effect of the present invention is believed to correlate with a binding state of Fe phase and the second phase.
- an average major axis of the second phase is preferably in a ⁇ 100> orientation or a ⁇ 110> orientation of the ferrite phase that is in contact with the second phase.
- This orientation relationship can be determined by usual electron beam diffraction or the like.
- a kind of second phase is described next.
- the second phase is a simple substance of or a composite compound of oxide, sulfide, carbide, nitride or an intermetallic compound
- a remarkable effect can be obtained.
- oxides including one or two of Fe, Mn, Si, Al, Cr, REM, Ti and Nb can be employed.
- sulfide sulfides including one or two of Ti , Mn, Cu, Ca and REM can be employed.
- carbide carbides including one or two of Fe, Ti, Nb, Si and Cr can be employed.
- nitride nitrides including one or two of Fe, Ti, Nb, Al, B and Cr can be employed.
- intermetallic compound intermetallic compounds including one or two of Fe, Ti, Nb, Al, Si and Mn can be employed.
- carbide a pearlite composition that is normally observed for steel, in specific, a layer composition including cementite and a ferrite phase generated due to a transformation of austenite at high temperature is excluded for the present invention as it cannot provide an effect of the present invention at all.
- metamorphic intermetallic compound there are NiAl, Ni 3 Al, Ni 3 (Al, Ti), N 2 TiAl, Ni 3 T i , Ni 3 Mo, Ni 4 Mo, Ni 3 Nb, Co 3 W, Fe 2 Mo, Fe 2 Ti, Fe 2 (Ni, Co) and the like.
- oxides, sulfides, carbides, nitrides and intermetallic compounds are a compound usually seen in a steel material, and a special compound is not necessarily employed. However, a special compound can still be formed to a morphology lying within the scope of the present invention.
- the kind of the phase is not limited to those mentioned above as only the representative elements are mentioned in the above.
- the second phase that exists in steel is not limited to one kind and a case where two or more kinds are combined is also included in the present invention. These may exist independently or may together form a composite compound. Moreover, a phase that is not included in the present invention from a morphological view can also be existed simultaneously.
- the important matter is the morphological feature of the second phase.
- This difference is thought to be affected by kind or amount of the second phase that can be formed in a steel sheet; a morphology difference that can be controlled by manufacture conditions as described later; and kind of the second phase itself that also correlates with a binding state with the matrix.
- classification of preferred kind of the second phase and the element forming the second phase can be made as shown below.
- the kind can be ranked as follows: intermetallic compound>carbide ⁇ nitride>oxide>sulfide.
- this order is made only by estimating the effect assuming that the morphology and the amount are the same, and there may be a case where assuring the amount or controlling the morphology is difficult depending on the manufacturing method or the kind of the second phase. Thus, this order is only for a rough indication.
- the effect of elements the following points can be mentioned.
- oxide preferred are those including Fe, Mn and REM; while Si, Al, Cr, Ti and Nb provide a small effect.
- sulfide preferred are Mn, Ca and REM; while Ti and Cu provide a small effect.
- carbide preferred are Cr, Ti and Si; while Fe and Nb provide a small effect.
- nitride preferred are Fe, Ti, B and Cr; while Nb and Al provide a small effect.
- an intermetallic compound preferred are Fe, Al, Si and Mn; while Ti and Nb provide a small effect.
- a region in a thickness direction of the steel sheet employed in this specification will be described with reference to FIG 1 .
- the terms '1/8 sheet thickness surface layer' and '1/4 sheet thickness center layer' indicate corresponding regions shown in FIG. 1 .
- a region corresponding to '1/8 sheet thickness surface layer' is present on both surfaces of the steel sheet, but those having only one ⁇ 1/8 sheet thickness surface layer' on any side can also be included in the scope of the present invention.
- the second phase which is the characteristic of the present invention is not necessarily uniformly dispersed in a whole area when distribution in a direction of the steel sheet is taken into consideration, and it may be unevenly distributed in the sheet thickness direction. It is rather better to form a multilayer constitution including a layer with many second phases and a layer with less second phases in a thickness direction, from the viewpoint of effect of the present invention. A mechanism for this is not clear, but it is believed that a layer with many second phases and a layer with less second phases restrict the deformation of one another thereby increasing the measure of work hardening, and thus a local deformation is controlled. This can be thought alternatively that an effect similar to a restricting relationship between the second phase and the matrix is occurring in macro-spaces.
- the volume fraction of the second phase (a volume fraction of 1/8 sheet thickness surface layer)/(a volume fraction of 1/4 sheet thickness center layer) ⁇ 10 is preferable, or regarding the number density of the second phase, (a volume fraction of 1/8 sheet thickness surface layer)/(a volume fraction of 1/4 sheet thickness center layer) ⁇ 10 is preferable.
- the ratios are preferably 20 or more, more preferably 50 or more, even more preferably 100 or more, even further preferably 200 or more.
- it is necessary to be careful not to form too many second phases in the surface layer part because it may cause a surface defect or may cause the sheet to break readily.
- the present invention applies only to a steel sheet having a sheet thickness of 0.400 mm or less. This is because there is no point of applying a technique limited to a uniform elongation to a steel sheet having a greater thickness as in the present invention because upon working, molding still takes place to a certain degree after the formation of constriction due to a local ductility.
- the technique can be used usefully to an extra thin steel sheet having a thickness of preferably 0.250 mm or less, more preferably 0.200 mm or less, even more preferably 0.150 mm or less.
- a preferred applicable material is a steel sheet satisfying a maximum strength ⁇ 350 MPa and HR30T Rockwell hardness ⁇ 54, according to a tensile test (specifically, a tensile test carried out with the use of a tensile test specimen having a parallel part of 25 mm wide and 60 mm long under conditions of a distance between marks of 50 mm and a deformation rate of 5 mm/min) carried out with the use of a JIS5 tensile test specimen. More preferred is a steel sheet satisfying a maximum strength 400 ⁇ MPa and HR30T Rockwell hardness ⁇ 57, and even more preferred is a steel sheet satisfying a maximum strengths ⁇ 450 MPa and HR30T Rockwell hardness ⁇ 61.
- the steel sheet of the present invention provides the characteristic in satisfying (uniform elongation)/(local elongations) ⁇ 1.0, according to a tensile test carried out with the use of a JIS5 tensile test specimen.
- the ratio is preferably 1.5 or more, more preferably 2.0 or more, even more preferably 3.5 or more, even further preferably 5.0 or more.
- the steel satisfies yield stress/maximum strengths ⁇ 0.9, more preferably 0.8 or less, even more preferably 0.7 or less, even further preferably 0.6 or less, according to a tensile test carried out with the use of a JIS5 tensile test specimen.
- a preferred embodiment includes rolling and elongating an oxide by rolling in a hot-rolling step to be modified into a preferable form. In order to do this, a certain degree of work amount is required, and a thickness of a steel slab subjected to casting is set to preferably 50 mm or more, more preferably 150 mm or more. In order for the rolled and elongated oxide to have an appropriate size, a size of the oxide before subjected to rolling and elongation is preferably between 10 ⁇ m and 25 ⁇ m.
- the oxide is rolled and elongated by rolling and accordingly an acicular oxide which is preferable for the present invention is obtained.
- the oxide is hardly rolled and elongated at a temperature lower than 1000°C, such as at about 900°C or below, it partly cracks, and oxides having a reasonable acicular morphology disperse at an appropriate interval in the steel sheet.
- a temperature control upon hot-rolling a strain amount for each temperature region and also a control of strain rate so as to control softening of work-hardened ferrite, also become important.
- the condition includes after cold rolling, performing a carburization treatment at a temperature ranging between 600 and 700°C under a condition of giving ⁇ (carburization time (sec))* (carburization temperature (°C)) ⁇ / ⁇ (carburizing gas concentration (%)) * (cooling rate in carburization treatment (°C/sec)) ⁇ ⁇ 20, simultaneously with or after a recrystallization annealing, thereby increasing a C amount by 0.0002% or more. If the temperature is out of above range, carburization efficiency decreases at a low temperature side, and on the contrary if the temperature is too high, the configuration of the carbide may be easily isotropic.
- the preferable configuration of the second phase can be achieved. Basically, since the carbide can be sufficiently grown with a gradual cooling treatment at a high temperature for a long time while suppressing the growth of the deposition nucleus of the carbide in a low C concentration, the development of the anisotropic second phase is remarkable.
- the carburization condition it is preferable to control the value of the above formula such that only surface part is carburized.
- This value may also depend on the plate thickness, and is preferably 500 or less, more preferably 200 or less.
- the condition of atmosphere including the type of carburizing gas may be the generally known condition.
- the carburizing method is not limited to the gas carburization illustrated herein, and the generally known carburizing method can be applied.
- 0.0002 % or more which is the increased amount of C may seem to be very small as the increased amount, but this amount is sufficient for exhibiting the effect of the present invention in consideration of the increased amount at a surface layer of the steel plate in an extra thin material.
- the condition includes after cold rolling, performing a nitriding treatment at a temperature ranging between 600 and 700°C under a condition of giving ⁇ (nitriding time (sec)) * (nitriding temperature (°C)) ⁇ / ⁇ (nitriding gas concentration (%))* (cooling rate in nitriding treatment (°C/sec)) ⁇ ⁇ 20, simultaneously with or after a recrystallization annealing, thereby increasing an N amount by 0.0002% or more.
- the condition of atmosphere including the type of nitriding gas may be the generally known condition.
- the nitriding method is not limited to the gas nitration illustrated herein, and the generally known nitriding method can be applied similar to the case of carburization.
- the intermetallic compound is used as the second phase
- the temperature before starting the cooling is too low, dissolving of the intermetallic compound becomes insufficient and the growth after that cannot be caused.
- the cooling speed is too rapid, the nucleus generation frequency of the intermetallic compound becomes high and the anisotropic growth is not occurred so that the isotropic intermetallic compound is formed with high density.
- the manufacturing methods of various second phases illustrated herein are different depending on elements forming the objective second phase and amounts thereof and not limited to the above described ranges. If the kind of elements forming the second phase, the type and amount of the second phase to be formed, and the directionality of the configuration to be controlled are known, suitable conditions can be sought within in a general metallurgical category and it is not difficult for a person skilled in the art to identify the conditions through several trial.
- a re-cold rolling may be performed after a recrystallization annealing for the hardness adjustment or plate thickness adjustment.
- the rolling reduction ranging from about several % near the skin-pass which is performed for the shape adjustment up to 50% or more similar to a cold rolling is practically used.
- the effect of the present invention is not damaged.
- the rolling reduction is too high, an absolute value of uniform elongation becomes small.
- a work-hardened amount in a uniform elongation region becomes small so that it is not a preferable method considering the application of the effect of the present invention.
- the rolling reduction is preferably 30% or less, more preferably 20% or less, further preferably 10% or less, and most preferably 3% or less.
- the effect of the present invention does not depend on the heat history and manufacturing history, after component adjustment and before annealing. Since a slab in case of performing a hot rolling is not limited to a manufacturing method such as a continuous casting process and does not depend on the heat history until reaching a hot rolling, the effect of the present invention-can be achieved even with a slab reheating method, CC-DR method directly heat rolling the cast slab without reheating, and a thin slab casting omitting the rough rolling or the like. Furthermore, the effect of the present invention can be obtained even with a dual phase region rolling having a finishing temperature of ⁇ + ⁇ phases and a continuous hot rolling which rolls by connecting a rough bar, without depending on a hot rolling condition.
- the steel of the present invention is particularly preferable when it is used for a member having a welded portion, because a uniform deformation property in a heat-affected portion is improved and the occurrence of a constricted part is suppressed.
- the steel plate of the present invention can be used with any surface treatment.
- the steel plate is not damaged by applying the surface treatment.
- the surface treatment includes applying tin, chrome (tin-free), Ni, zinc, aluminum or the like which is generally performed for a metal plating.
- the effect of the present invention can be obtained with respect to a primitive plate for a laminate steel plate coated with an organic film which is used recently.
- the steel plate of the present invention can be generally used for electric apparatuses, electronic components, architectural materials or metal containers, and also can be used in other applications if the use thereof includes the task similar to the above-described matter.
- 'Average major axis/average minor axis' it is a ratio of 'average major axis' to 'average minor axis'.
- the value is an index showing an anisotropy degree of oxide which is the root of providing effects of the present invention.
- 'Flange formability' a body of three-piece cans each prepared by curling and welding a flat sheet into a cylindrical form was prepared by number of 10,000 pieces. Then, each of them was subjected to a flange forming using a die and mold. For a result, when all cans were successfully flange formed without causing breakage, it was ranked as 'pass', and when even 1 can was broken, it was ranked as 'failure'.
- Example 1 Experimental results when oxide was used as the second phase are shown in Table 2.
- a form of the oxide was controlled mainly by a size of the oxide depending on a casting condition and a measure of rolling and elongation depending on a hot-rolling condition. "A number density" of oxide was determined by observing cross section with SEM. It was confirmed that good and uniform elongation is achieved by controlling the state of oxide to be within the scope of the present invention.
- Example 2 Experimental results when sulfide was used as the second phase are shown in Table 3.
- a form of sulfide was controlled mainly by a size of the sulfide depending on a casting condition and a measure of rolling and elongation depending on a hot-rolling condition.
- "A number density" of sulfide was determined by observing cross section with TEM. It was confirmed that good and uniform elongation is achieved by controlling the state of sulfide to be within the scope of the present invention.
- Example 3 Experimental results when carbide or nitride was used as the second phase are shown in Table 4.
- a form of carbide or nitride was controlled mainly by a carburizing condition or a nitriding condition.
- All "base sheet” in this Example are steel sheets subjected to recrystallization and annealing at 700°C.
- properties of a sheet subjected to a re-cold rolling only and not to a carburizing or nitriding treatment and prepared to have the same hardness degree to those subjected to carburization or nitriding treatment were also shown.
- Observation of carbide or nitride was made at 1/8 sheet thickness and at the center of sheet thickness.
- the "number density" of carbide or nitride was determined by observing residue that remained when 1/8 sheet thickness surface layer or 1/4 sheet thickness center layer was electrolyzed, using SEM.
- the "volume fraction” and “number density” described regarding to the second phase and values described regarding to the main phase are values for the 1/8 sheet thickness layer surface. It was confirmed that a good and uniform elongation is achieved by controlling the state of sulfide to be within the scope of the present invention.
- Example 4 Experimental results when intermetallic compound was used as the second phase are shown in Table 5.
- Ni 3 Al was used as the intermetallic compound.
- a form of Ni3Al was controlled mainly by a recrystallization and annealing condition, particularly controlled by a fusing degree depending on an annealing temperature, and by nucleation/crystal growth caused by a cooling process carried out thereafter. All of the "base sheets” in this Example are cold-rolled steel sheets and nothing else.
- “A number density" of Ni 3 Al was determined by observation with TEM. When comparison with steel sheets other than the sheets of Examples 1 to 4 was made, it was confirmed that good characteristics can be obtained by controlling the state of intermetallic compound to be within the scope of the present invention.
- a hard extra-thin material exhibiting more uniform elongation capacity while preventing a local deformation (constriction) from occurring up to a high strained region, even if the same strength and the same total elongation are employed, can be obtained.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2006102766 | 2006-04-04 | ||
PCT/JP2007/057575 WO2007116913A1 (ja) | 2006-04-04 | 2007-04-04 | 硬質極薄鋼板およびその製造方法 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP2003221A1 EP2003221A1 (en) | 2008-12-17 |
EP2003221A4 EP2003221A4 (en) | 2014-12-03 |
EP2003221B1 true EP2003221B1 (en) | 2016-05-25 |
Family
ID=38581203
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP07741011.6A Active EP2003221B1 (en) | 2006-04-04 | 2007-04-04 | Hard extra-thin steel sheet and method for manufacturing the same |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP2003221B1 (es) |
JP (1) | JP5058978B2 (es) |
KR (1) | KR101065545B1 (es) |
CN (1) | CN101415851B (es) |
ES (1) | ES2575997T3 (es) |
WO (1) | WO2007116913A1 (es) |
Families Citing this family (42)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5251255B2 (ja) * | 2008-05-21 | 2013-07-31 | 新日鐵住金株式会社 | 局部変形能が小さい硬質極薄鋼板およびその製造方法 |
TWI412607B (zh) * | 2009-03-30 | 2013-10-21 | Nippon Steel & Sumitomo Metal Corp | 滲碳鋼零件 |
US9689052B2 (en) * | 2009-05-18 | 2017-06-27 | Nippon Steel & Sumitomo Metal Corporation | Very thin steel sheet and production method thereof |
KR101286172B1 (ko) * | 2009-12-04 | 2013-07-15 | 주식회사 포스코 | 가공성 및 내열성이 우수한 고강도의 가공용 고내열 냉연강판 및 그 제조방법 |
KR101308719B1 (ko) * | 2009-12-04 | 2013-09-13 | 주식회사 포스코 | 가공성, 내열성 및 내변색성이 우수한 고강도의 가공용 고내열 냉연강판 및 그 제조방법 |
DE102010003997A1 (de) * | 2010-01-04 | 2011-07-07 | Benteler Automobiltechnik GmbH, 33102 | Verwendung einer Stahllegierung |
JP5227359B2 (ja) | 2010-04-07 | 2013-07-03 | トヨタ自動車株式会社 | オーステナイト系耐熱鋳鋼 |
JP5540885B2 (ja) * | 2010-05-20 | 2014-07-02 | 新日鐵住金株式会社 | 溶融めっき熱延鋼板およびその製造方法 |
US8882942B2 (en) | 2010-07-09 | 2014-11-11 | Nippon Steel & Sumitomo Metal Corporation | Ni-added steel plate and method of manufacturing the same |
CN102443743A (zh) * | 2010-10-09 | 2012-05-09 | 王振民 | 多元合金耐磨钢固定锲 |
KR101351944B1 (ko) * | 2010-12-08 | 2014-01-23 | 주식회사 포스코 | 내열성 및 내변색성이 우수한 가공용 냉연강판 및 그 제조방법 |
KR101351951B1 (ko) * | 2010-12-08 | 2014-01-23 | 주식회사 포스코 | 내열성이 우수한 가공용 고강도 냉연강판 및 그 제조방법 |
CN102071357B (zh) * | 2011-01-05 | 2013-07-31 | 武钢集团昆明钢铁股份有限公司 | 富氮铌钒微合金化500MPa、550MPa高强度抗震钢筋的冶炼方法 |
CN102071358A (zh) * | 2011-01-26 | 2011-05-25 | 天津钢铁集团有限公司 | 一种屈服强度550MPa级低合金高强度钢板及生产方法 |
JP5987284B2 (ja) | 2011-09-07 | 2016-09-07 | 日立化成株式会社 | 焼結合金およびその製造方法 |
JP5059244B1 (ja) | 2011-09-28 | 2012-10-24 | 新日本製鐵株式会社 | Ni添加鋼板およびその製造方法 |
US9765678B2 (en) | 2012-05-10 | 2017-09-19 | Hitachi Metals, Ltd. | Heat-resistant, austenitic cast steel having excellent machinability and exhaust member made thereof |
CN103045960B (zh) * | 2012-12-21 | 2015-02-04 | 无锡市华尔泰机械制造有限公司 | 一种风力塔筒用法兰及制造工艺 |
CN104152811A (zh) * | 2014-07-25 | 2014-11-19 | 安徽霍山科皖特种铸造有限责任公司 | 一种高韧性钢 |
CN104894472B (zh) * | 2015-05-22 | 2017-03-08 | 武汉钢铁(集团)公司 | 高氧含量钢及其冶炼方法 |
CN105013833B (zh) * | 2015-06-30 | 2017-04-05 | 攀钢集团西昌钢钒有限公司 | 极薄规格冷硬带钢板形控制方法 |
WO2017043660A1 (ja) * | 2015-09-11 | 2017-03-16 | 新日鐵住金株式会社 | 鋼板およびほうろう製品 |
KR20190031278A (ko) * | 2016-07-19 | 2019-03-25 | 신닛테츠스미킨 카부시키카이샤 | 고주파 담금질용 강 |
US20190241997A1 (en) * | 2016-07-19 | 2019-08-08 | Nippon Steel & Sumitomo Metal Corporation | Steel for Induction Hardening |
JP6384627B2 (ja) * | 2016-07-19 | 2018-09-05 | 新日鐵住金株式会社 | 高周波焼入れ用鋼 |
US20190300993A1 (en) * | 2016-07-19 | 2019-10-03 | Nippon Steel & Sumitomo Metal Corporation | Steel for Induction Hardening |
US20190300994A1 (en) * | 2016-07-19 | 2019-10-03 | Nippon Steel & Sumitomo Metal Corporation | Steel for Induction Hardening |
KR101918720B1 (ko) * | 2016-12-19 | 2018-11-14 | 주식회사 포스코 | 무방향성 전기강판 및 그 제조방법 |
CN107245669A (zh) * | 2017-06-22 | 2017-10-13 | 威斯卡特工业(中国)有限公司 | 一种铸造用母合金及其生产方法 |
CN108374126B (zh) * | 2018-04-17 | 2019-12-03 | 东北大学 | 一种高强度细晶粒钢筋及其制备方法 |
WO2019221286A1 (ja) * | 2018-05-17 | 2019-11-21 | 日本製鉄株式会社 | 鋼板およびほうろう製品 |
CN108914009A (zh) * | 2018-08-28 | 2018-11-30 | 宝钢湛江钢铁有限公司 | Al+Ti系低成本高强船板钢及其制造方法 |
KR102179214B1 (ko) * | 2018-11-30 | 2020-11-16 | 주식회사 포스코 | 법랑용 냉연 강판 및 그 제조방법 |
CN110029278B (zh) * | 2019-03-28 | 2020-06-05 | 江苏利淮钢铁有限公司 | 一种高纯净度超低碳低铝钢及其生产方法 |
KR102326324B1 (ko) * | 2019-12-20 | 2021-11-12 | 주식회사 포스코 | 고강도 주석 도금원판 및 그 제조방법 |
KR102348509B1 (ko) * | 2019-12-20 | 2022-01-06 | 주식회사 포스코 | 법랑용 강판 및 그 제조방법 |
EP3875626B1 (de) * | 2020-03-06 | 2024-07-17 | ThyssenKrupp Rasselstein GmbH | Verpackungsblecherzeugnis |
CN111394656B (zh) * | 2020-05-06 | 2022-03-18 | 合肥易知谷机械设计有限公司 | 一种结晶器 |
CN113564476A (zh) * | 2021-07-28 | 2021-10-29 | 马鞍山钢铁股份有限公司 | 一种渗氮钢用基板及生产方法、具有优良耐腐蚀渗氮钢及其渗氮方法和应用 |
CN115852243B (zh) * | 2021-09-24 | 2024-07-12 | 宝山钢铁股份有限公司 | 一种高耐蚀耐热预镀镍电池壳钢及其制造方法 |
CN114134423B (zh) * | 2021-12-02 | 2022-05-17 | 东北大学 | 一种超短流程稀土取向硅钢及其制备方法 |
CN115323269A (zh) * | 2022-07-21 | 2022-11-11 | 阳春新钢铁有限责任公司 | 一种控制高拉速条件下q235圆钢裂纹的方法 |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH02118026A (ja) | 1988-10-28 | 1990-05-02 | Kawasaki Steel Corp | 缶用鋼板の製造方法 |
JPH086143B2 (ja) | 1990-03-06 | 1996-01-24 | 新日本製鐵株式会社 | 板取り性が優れた極薄溶接缶用鋼板の製造法 |
JP3726371B2 (ja) | 1996-08-30 | 2005-12-14 | Jfeスチール株式会社 | 時効硬化性が大きく、材質安定性に優れる缶用鋼板およびその製造方法 |
JP4213833B2 (ja) | 1999-10-21 | 2009-01-21 | 新日本製鐵株式会社 | 溶接部靱性に優れた高靱性高張力鋼とその製造方法 |
JP2002003987A (ja) * | 2000-06-26 | 2002-01-09 | Nippon Steel Corp | 溶接性と低温靭性に優れた低降伏比高張力鋼およびその製造方法 |
CN1276987C (zh) * | 2001-10-19 | 2006-09-27 | 住友金属工业株式会社 | 具有优异的可加工性和成型精度的薄钢板及其制造方法 |
AU2002363283B2 (en) * | 2001-10-29 | 2005-07-21 | Nippon Steel Corporation | Steel sheet for vitreous enameling and method for producing the same |
US7494551B2 (en) * | 2002-06-17 | 2009-02-24 | Jfe Steel Corporation | Ferritic stainless steel plate with Ti and method for production thereof |
JP3817216B2 (ja) * | 2002-11-15 | 2006-09-06 | 新日本製鐵株式会社 | 溶接熱影響部の靭性に優れた鋼材および鋼溶接部材 |
JP4315844B2 (ja) | 2004-03-05 | 2009-08-19 | 株式会社神戸製鋼所 | 塗膜密着性に優れた高強度冷延鋼板 |
EP1806420A4 (en) * | 2004-09-09 | 2008-04-23 | Nippon Steel Corp | STEEL PLATE FOR EXTREMELY THIN CONTAINERS AND RELATED MANUFACTURING METHOD |
JP4245540B2 (ja) | 2004-10-04 | 2009-03-25 | 新光機器株式会社 | ハンディ式キャップチップ取外し装置 |
KR100948998B1 (ko) * | 2005-03-31 | 2010-03-23 | 가부시키가이샤 고베 세이코쇼 | 도막 밀착성, 가공성 및 내수소취화 특성이 우수한 고강도 냉연 강판 및 자동차용 강 부품 |
US20090047168A1 (en) * | 2005-11-09 | 2009-02-19 | Hidekuni Murakami | Continuously Cast Enameled Steel Sheet Remarkably Excellent in Fishscale Resistance and Method of Production of the Same |
-
2007
- 2007-04-04 CN CN2007800116843A patent/CN101415851B/zh active Active
- 2007-04-04 WO PCT/JP2007/057575 patent/WO2007116913A1/ja active Application Filing
- 2007-04-04 KR KR1020087024085A patent/KR101065545B1/ko active IP Right Grant
- 2007-04-04 JP JP2008509867A patent/JP5058978B2/ja active Active
- 2007-04-04 ES ES07741011.6T patent/ES2575997T3/es active Active
- 2007-04-04 EP EP07741011.6A patent/EP2003221B1/en active Active
Also Published As
Publication number | Publication date |
---|---|
KR20080106330A (ko) | 2008-12-04 |
CN101415851B (zh) | 2011-06-08 |
EP2003221A4 (en) | 2014-12-03 |
EP2003221A1 (en) | 2008-12-17 |
WO2007116913A1 (ja) | 2007-10-18 |
KR101065545B1 (ko) | 2011-09-19 |
JP5058978B2 (ja) | 2012-10-24 |
JPWO2007116913A1 (ja) | 2009-08-20 |
ES2575997T3 (es) | 2016-07-04 |
CN101415851A (zh) | 2009-04-22 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP2003221B1 (en) | Hard extra-thin steel sheet and method for manufacturing the same | |
EP3415653B1 (en) | High-strength galvanized steel sheet and method for producing same | |
EP3309273B1 (en) | Galvannealed steel sheet and method for manufacturing same | |
EP2246456B9 (en) | High-strength steel sheet and process for production thereof | |
EP3904552B1 (en) | High-strength hot-dip galvanized steel sheet and method for manufacturing same | |
EP2138599B1 (en) | High-strength hot-dip galvanized steel sheet and method for producing the same | |
EP1616970B1 (en) | High strength hot-rolled steel plate | |
KR101225404B1 (ko) | 고강도 강판 및 그 제조 방법 | |
WO2018124157A1 (ja) | 高強度亜鉛めっき鋼板及びその製造方法 | |
EP2530180A1 (en) | Steel sheet and process for producing steel sheet | |
WO2020090303A1 (ja) | 高強度鋼板およびその製造方法 | |
EP2695961B1 (en) | High-strength steel sheet excellent in workability and manufacturing method thereof | |
EP1972698A1 (en) | Hot-dip zinc-coated steel sheets and process for production thereof | |
EP1741800A1 (en) | Steel sheet for can and method for production thereof | |
EP2554705A1 (en) | Hot-dip galvanized steel sheet with high tensile strength and superior processability and method for producing same | |
EP2258886A1 (en) | High-strength hot-dip galvanized steel sheet with excellent processability and process for producing the same | |
EP2586886A1 (en) | High-tension/hot-rolled steel sheet having excellent workability, and method for producing same | |
EP2180070A1 (en) | Process for manufacturing high-strength hot-rolled steel sheet | |
EP3889283B1 (en) | High-strength steel sheet and method for producing the same | |
EP2765211A1 (en) | High-tensile-strength hot-rolled steel sheet and method for producing same | |
EP3705592A1 (en) | High-strength cold-rolled steel sheet, high-strength plated steel sheet, and production methods therefor | |
WO2021186510A1 (ja) | 鋼板 | |
WO2021251276A1 (ja) | 鋼板及びその製造方法 | |
EP3231886B1 (en) | Complex-phase steel sheet with excellent formability and manufacturing method therefor | |
EP2492363A1 (en) | Bake-hardenable cold rolled steel sheet with superior strength, galvannealed steel sheet using the cold rolled steel sheet and method for manufacturing the cold rolled steel sheet |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20081029 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): BE DE ES FR GB |
|
DAX | Request for extension of the european patent (deleted) | ||
RBV | Designated contracting states (corrected) |
Designated state(s): BE DE ES FR GB |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: NIPPON STEEL & SUMITOMO METAL CORPORATION |
|
A4 | Supplementary search report drawn up and despatched |
Effective date: 20141104 |
|
RIC1 | Information provided on ipc code assigned before grant |
Ipc: C21D 1/06 20060101ALI20141029BHEP Ipc: C22C 38/60 20060101ALI20141029BHEP Ipc: C22C 38/00 20060101AFI20141029BHEP Ipc: B21B 3/00 20060101ALI20141029BHEP Ipc: C21D 8/04 20060101ALI20141029BHEP Ipc: C21D 9/48 20060101ALI20141029BHEP Ipc: B21B 1/26 20060101ALI20141029BHEP Ipc: C21D 9/46 20060101ALI20141029BHEP |
|
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
INTG | Intention to grant announced |
Effective date: 20160105 |
|
GRAS | Grant fee paid |
Free format text: ORIGINAL CODE: EPIDOSNIGR3 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): BE DE ES FR GB |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: FG4D |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: MURAKAMI, HIDEKUNI |
|
REG | Reference to a national code |
Ref country code: ES Ref legal event code: FG2A Ref document number: 2575997 Country of ref document: ES Kind code of ref document: T3 Effective date: 20160704 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R096 Ref document number: 602007046431 Country of ref document: DE |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R097 Ref document number: 602007046431 Country of ref document: DE |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 11 |
|
26N | No opposition filed |
Effective date: 20170228 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 12 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R082 Ref document number: 602007046431 Country of ref document: DE Representative=s name: VOSSIUS & PARTNER PATENTANWAELTE RECHTSANWAELT, DE Ref country code: DE Ref legal event code: R081 Ref document number: 602007046431 Country of ref document: DE Owner name: NIPPON STEEL CORPORATION, JP Free format text: FORMER OWNER: NIPPON STEEL & SUMITOMO METAL CORPORATION, TOKYO, JP |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20240229 Year of fee payment: 18 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20240308 Year of fee payment: 18 Ref country code: BE Payment date: 20240319 Year of fee payment: 18 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20240227 Year of fee payment: 18 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: ES Payment date: 20240507 Year of fee payment: 18 |