CN102471821B - Process for production of cold-rolled steel sheet having excellent press moldability, and cold-rolled steel sheet - Google Patents
Process for production of cold-rolled steel sheet having excellent press moldability, and cold-rolled steel sheet Download PDFInfo
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- 239000010960 cold rolled steel Substances 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000004519 manufacturing process Methods 0.000 title claims description 26
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 46
- 239000010959 steel Substances 0.000 claims abstract description 46
- 238000005097 cold rolling Methods 0.000 claims abstract description 35
- 238000000137 annealing Methods 0.000 claims abstract description 28
- 238000001816 cooling Methods 0.000 claims abstract description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 229910052742 iron Inorganic materials 0.000 claims abstract description 5
- 239000000203 mixture Substances 0.000 claims description 19
- 238000002791 soaking Methods 0.000 claims description 18
- 238000005554 pickling Methods 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000005096 rolling process Methods 0.000 abstract description 14
- 229910052759 nickel Inorganic materials 0.000 abstract description 7
- 239000002253 acid Substances 0.000 abstract description 2
- 238000005098 hot rolling Methods 0.000 description 12
- 238000000748 compression moulding Methods 0.000 description 11
- 229910000734 martensite Inorganic materials 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 7
- 239000004973 liquid crystal related substance Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 229910001563 bainite Inorganic materials 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- 229910000797 Ultra-high-strength steel Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910001337 iron nitride Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000007669 thermal treatment Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0006—Details, accessories not peculiar to any of the following furnaces
-
- 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
- C21D9/0037—Rotary furnaces with vertical axis; Furnaces with rotating floor
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—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
- C22C38/04—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
- C22C38/18—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
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with 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
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Disclosed are: a cold-rolled steel sheet which undergoes less load during cold rolling and has excellent press moldability and high strength; and a process for producing the cold-rolled steel sheet. A hot-rolled steel sheet comprising 0.10 to 0.30 mass% of C, 0.2 mass% or more of Mn, 0.01 mass% or more of Ni (wherein the sum total of Mn and Ni is 0.5 to 2.5 mass%), and 1.2 to 9.0 mass% of Cr, with the remainder being iron and unavoidable impurities, and having a tensile strength of 1000 MPa or less is washed with an acid, and is subjected to cold rolling at a total rolling ratio of 60% or more, thereby producing a cold-rolled steel sheet. The cold-rolled steel sheet is subjected to the final continuous annealing treatment at a homogenizing temperature of 750 DEG C or higher and a cooling rate of 3 to 100 DEG C/s. In this manner, a cold-rolled steel sheet having a tensile strength of 1280 MPa or more, a breaking elongation of 3% or more, and a thickness of 0.05 to 0.60 mm.
Description
Technical field
The present invention relates to a kind of manufacture method of cold-rolled steel sheet of compression moulding excellence and the cold-rolled steel sheet of manufacturing by this manufacture method.
Background technology
Be used for liquid crystal frame parts and the motor car engine gasket etc. of mobile telephone and notebook computer etc. greatly mainly with coldmoulding, therefore, the cold-rolled steel sheet of the thin plate using requires compression moulding.
In addition, in the electronic unit taking notebook computer and mobile telephone, digital camera as representative and motor car engine with in the parts such as gasket, also require lightweight and miniaturization, for by these parts lightweights, miniaturization, need to be by steel plate attenuate, in addition, because identical intensity can not be guaranteed the intensity as pressed part, therefore, need to provide a kind of thin size and there is high-intensity high tensile steel plate.
From this technical background, for the purposes of the reinforcing member of the safety cylinder as automobile or car door, proposing a kind of tensile strength with martensite or bainite structure is ultrahigh-strength steel plates (with reference to patent documentation 1) more than 1180MPa.
In addition, in patent documentation 2, proposed a kind of in continuous annealing, steel plate is heated to recrystallization temperature more than, soaking after annealing, implemented the gasket material cold-rolled steel sheet of twice cold rolling elasticity excellence.
Prior art document
Patent documentation
Patent documentation 1: specially permit No. 3254106 communique
Patent documentation 2: Unexamined Patent 9-194935 communique
Summary of the invention
Invent problem to be solved
But, as the high tensile steel plate of recording in patent documentation 1 and patent documentation 2, make ductility reduce in order to realize high strength, while there is compression moulding, crack the poor such problem of compression moulding.
In addition, in high tensile hot rolled steel sheet cold rolling, due to thin size, the load when cold rolling increases, and also exists because operability reduces, production loss increases the such problem of productivity of damaging.
The object of the invention is to, in order to solve above-mentioned problem, provide a kind of load when cold rolling little, and high-intensity cold-rolled steel sheet and the manufacture method thereof of compression moulding excellence.
For solving the means of problem
(1) manufacture method of cold-rolled steel sheet of the present invention is characterised in that,
Be that hot-rolled steel sheet below 1000MPa carries out after pickling by tensile strength, the rate of being rolled adds up to more than 60% cold rolling, make cold-rolled steel sheet, soaking temperature is set as more than 750 DEG C, speed of cooling is set as 3 DEG C/s～100 DEG C/s, carries out final continuous annealing processing, the cold-rolled steel sheet that make tensile strength and be that 1280MPa is above, elongation at break is more than 3%, thickness is 0.05～0.60mm, wherein, described hot-rolled steel sheet comprises following composition in quality %:
C：0.10～0.30、
More than Mn:0.2,
More than Ni:0.01,
Mn+Ni：0.5～2.5、
Cr：1.2～9.0，
Remainder is iron and inevitable impurity.
(2) manufacture method of cold-rolled steel sheet of the present invention is characterised in that, in described (1), the thickness of described hot-rolled steel sheet is 1.2～3.0mm.
(3) cold-rolled steel sheet of the present invention is characterised in that,
Be that hot-rolled steel sheet below 1000MPa carries out after pickling by tensile strength, the rate of being rolled adds up to more than 60% cold rolling, make cold-rolled steel sheet, soaking temperature is set as more than 750 DEG C, speed of cooling is set as 3 DEG C/s～100 DEG C/s, carries out final continuous annealing processing, the cold-rolled steel sheet that make tensile strength and be that 1280MPa is above, elongation at break is more than 3%, thickness is 0.05～0.60mm, wherein, described hot-rolled steel sheet comprises following composition in quality %:
C：0.10～0.30、
More than Mn:0.2,
More than Ni:0.01,
Mn+Ni：0.5～2.5、
Cr：1.2～9.0，
Remainder is iron and inevitable impurity.
(4) cold-rolled steel sheet of the present invention is characterised in that, in described (3), the thickness of described hot-rolled steel sheet is 1.2～3.0mm.
The effect of invention
According to the present invention, can provide a kind of load alleviating when cold rolling, high strength and guaranteed the cold-rolled steel sheet of the compression moulding excellence of ductility.
In addition, according to the manufacture method of cold-rolled steel sheet of the present invention, can provide a kind of desired thickness of starting material having as liquid crystal frame or the frame parts etc. of the petrolic gasket for automobile, notebook computer, mobile telephone, digital camera: 0.05mm～0.6mm, tensile strength: 1280MPa is above, elongation at break: cold-rolled steel sheet more than 3%, that simultaneously possess intensity and processibility.
Embodiment
The composition > of < hot-rolled steel sheet
The composition of hot-rolled steel sheet, in quality %, is set as following scope.
C:0.10～0.30, Mn:0.2 are above, Ni:0.01 is above, Mn+Ni:0.5～2.5, Cr:1.2～9.0, remainder: Fe and inevitable element.
C generates the low temperature phase change tissues such as martensite for making in steel plate, obtains the important element of high tensile strength.
When C amount is lacked, can not get the tensile strength of needs, therefore, is 0.10 by lower limit set.On the other hand, when too much, make hot rolling and the rolling load when cold rolling increase, shape is deteriorated etc., hinders productivity, therefore the upper limit is set as to 0.30.The scope of preferred C is 0.15～0.25.
In the present invention, Mn and Ni are the element that improves hardenability, makes low temperature phase change tissue generate in the time of continuous annealing, the tensile strength of giving the cold-rolled steel plate hight after continuous annealing.In the time that the total amount of two kinds of compositions is very few, after continuous annealing, can not get intensity, so be 0.5 by lower limit set.On the other hand, when too much, effect is saturated, and reduces because segregation etc. makes processibility, so the upper limit is set as to 2.5.
In addition, about Mn and Ni scope separately, because Mn prevents the red heat causing as the S of impurity, therefore need to make it to contain more than 0.20, because Ni guarantees the toughness after thermal treatment, therefore need to add more than 0.01.Because the price of Ni is high, therefore, adjust cost favourable with Mn.
Cr, also for improving the element of hardenability, makes low temperature phase change tissue generate in the time of continuous annealing, obtains high tensile strength.When content is few, can not get tensile strength after continuous annealing, is therefore 1.2 by lower limit set.Too much time, effect is saturated, and causes that meaningless cost improves, and is therefore set as 9.0 by the upper limit.More preferably 2.0～5.5.
Si is to making the effective element of cold-rolled steel sheet high strength, although The more the better in order to reach this object, while exceeding 2.0%, cause cold rolling load increase, shape deteriorated, therefore, higher limit is set as to 2.0%.
P is the composition that makes crystal grain miniaturization, although from improving the intensity of cold-rolled steel sheet, expect to add by a certain percentage, but then, owing to causing embrittlement at grain boundary segregation, is therefore set as below 0.06%.
S is for produce red hot short impurity component in hot rolling, expects as far as possible less, but can not prevent that the desulfurization in operation is also limited from the sneaking into of raw material etc. completely, and therefore, to a certain degree residual is also inevitable.The fervid fragility causing due to a small amount of residual S can be alleviated by Mn, therefore, the higher limit of S composition is set as to 0.06%.
Because Cu improves intensity by solution strengthening or precipitation strength, therefore can add certain amount, the embrittlement while likely causing hot rolling but then.Therefore, the upper limit is set as to 0.5%.
Al is added in molten steel as reductor in the time of steel processed, reacts as AlN and separates out with solid solution N, contributes to the refinement of crystal grain.On the other hand, add while exceeding 0.10%, N fixedly becomes obviously, and the solution strengthening of N reduces, so be set as below 0.10%.
Although Ti has crystal grain thinning, suppresses crystal grain-growth, improves solidity to corrosion texts, adding too much effect also can be saturated, so be set as below 0.30%.
N is the same with C, Mn, the intensity in order to give cold-rolled steel plate hight, make the yield strength needed composition that strengthened, when fewer than 0.002%, on steel processed, produce difficulty, on the other hand, add while exceeding 0.015%, the effective rate of utilization of the iron-nitride adding in the time of steel processed obviously reduces, poor stability, and the anisotropy while simultaneously making compression moulding is obviously deteriorated.
And then crack on the surface of continuous casting sheet, become casting flaw, therefore, in the present invention, it is desirable to N composition range to be set as below 0.015%.
The > of < manufacturing process
Below, the manufacture method of cold-rolled steel sheet of the present invention is described.
< steel > processed
Carry out melting with converter or electric furnace, carry out composition adjustment in mentioned component scope, make slab sheet.
< hot rolling >
The slab sheet that composition has been adjusted is made the thin plate of thickness of slab 1.2～3.0mm by hot rolling.When thickness of slab is thin, the load while causing hot rolling increases, and is therefore 1.2 by lower limit set.In addition, when thickness of slab is thick, in the time of thereafter cold rolling, cause that load increases, therefore the upper limit is set as to 3.0.
In hot-rolled process, the slab sheet of mentioned component scope is set as to 1100 DEG C of above, coiling Temperature Settings by Heating temperature and is 600 DEG C and carries out above hot rolling.When 1100 DEG C of the Heating temperature less thaies of slab sheet, because the positive decomposition solid solution deficiency of N, hot rolling load uprises, therefore not preferred.
In addition, by coiling Temperature Setting be 600 DEG C～800 DEG C.When coiling temperature is low, cause hot-rolled steel sheet high strength, thus not preferred when cold rolling, be therefore 600 DEG C by the lower limit set of coiling temperature.
On the other hand, when coiling temperature exceedes 800 DEG C, in the time of hot rolling, promote scale to generate, in pickling, cause that load increases, and is therefore set as the upper limit 800 DEG C when desquamating.
The hot-rolled steel sheet of manufacturing under condition as above, can make tensile strength reach below 1000MPa.This is that while exceeding 1000MPa because of tensile strength, the rolling load when cold rolling increases, therefore not preferred.
< pickling >
After the surperficial scale generating while removing hot rolling according to common method in acid bath, carry out cold rolling, continuous annealing.
The cold rolling > of <
The cold rolling one or many that is divided into, to add up to more than 60% rolling rate to be rolled, until the product thickness 0.05～0.6mm of regulation.When this thickness becomes also thin than 0.05mm, less rigid, in the time of the product such as liquid crystal frame or frame parts of the petrolic gasket for automobile, notebook computer, mobile telephone, digital camera, shape becomes easy distortion sometimes, can not manufacture a product.
In addition, when this thickness becomes also thick than 0.6mm,, in the time of the product such as liquid crystal frame or frame parts of the petrolic gasket for automobile, notebook computer, mobile telephone, digital camera, weight becomes also larger than design load sometimes, can not realize miniaturization.
Although the upper limit of the total rolling rate in cold rolling does not have special stipulation, is set as 98%.
In addition, after cold rolling, by carrying out 500 DEG C of above continuous annealings or 500 DEG C of above batch annealings, can make the milled sheet of work hardening softening, can again carry out cold rolling.
Cold rolling method and cold rolling number of times do not specify, and can suitably select according to target thickness of slab.
< continuous annealing >
Continuous annealing is the annealing of removing the deformation of the plate when cold rolling, and this continuous annealing can all be carried out carrying out repeatedly cold rolling in the situation that at every turn.
In addition, in the present invention, in final continuous annealing, the soaking of carrying out above below the above 100s of 1s with 750 DEG C of soaking temperatures keeps.When 750 DEG C of soaking temperature less thaies, owing to not exceeding Ae3 transformation temperature, therefore can not get sufficient tensile strength.
In addition, even if soaking temperature exceedes 1000 DEG C, there is no special advantage yet, industrial be also unhelpful, therefore the upper limit is set as to 1000 DEG C.
This final continuous annealing is to make part or all austenitizing by heating, and cooling by thereafter makes them become mutually martensite etc.
In the present invention, can obtain according to the amount of this martensitic amount and alloying element the intensity of regulation.
Taking above-mentioned soaking temperature as more than 750 DEG C, after soaking keeps below 1s above 100s, so that 3 DEG C of speed of cooling/s～100 DEG C/s carries out cooling.Cooling by this, make the austenite structure of plate become the tissues such as martensite, tempered martensite, bainite.In the time of 3 DEG C/s of above-mentioned speed of cooling less than, the generation of the low temperature phase change tissue of martensite etc. becomes insufficient, can not get the intensity needing.In addition, when speed of cooling exceedes 100 DEG C/s, although obtained the intensity needing, the shape variation of steel plate, therefore, is unsuitable for suppressing purposes etc.
In the present invention, for the speed of cooling after continuous annealing, in order to ensure shape, carry out coolingly with speed of cooling very slow compared with using the quenching of general water etc., make the generation of low temperature phase change tissue, obtain high tensile steel plate.
Be Mn and Ni for the effective austenite stabilizer element of quenching element as general, although for the intensity that obtains with above-mentioned speed of cooling needing need to be added equivalent, but because the interpolation meeting of equivalent brings high intensity after hot rolling, cold rolling time load is increased, hinder productivity, cause the increase of production cost.
Therefore, in the present invention, by Mn and Ni addition are set lessly, and compound interpolation is as the Cr of ferritic stabilizer, can make after hot rolling, for more soft, in the continuous annealing after cold rolling, to manufacture high tensile steel plate, can significantly reduce and manufacture load.
In addition, after cooling after final continuous annealing, also can carry out as required 600 DEG C of following temper, the present invention forms quenching structure with lower speed of cooling, therefore, when cooling, also can obtain the effect equal with temper, can omit tempering process.By omitting tempering process, can contribute to significantly to cut down to manufacture and load.
By above-mentioned continuous annealing, the tensile strength that can make the cold-rolled steel sheet obtaining by manufacture method of the present invention is more than 1280MPa.By thering is such intensity, when the petrolic gasket using cold-rolled steel sheet as automobile uses, can not cause gas leakage.
In addition, for lightweight makes thickness of slab attenuation, being applied in the liquid crystal frame of notebook computer, mobile telephone, digital camera or the situation of frame parts, the in the situation that of particularly use, also can guarantee the rigidity as parts in mobile purposes.
In addition, by the manufacture method in the present invention, the elongation at break that can make cold-rolled steel sheet is more than 3%.The value that represents the elongation at break of ductility is important in the situation that being pressed by the purposes such as gasket or electronic unit as motor car engine.When elongation at break less than 3%, easily crack in processing departments such as slight expansion-molded or 90 ° of bendings.
Steel sheet there is by the steel plate of above-mentioned manufacture method manufacturing the tissue that volume fraction is more than 60% martensite, tempered martensite, bainite structure etc., even also can be manufactured the steel plate that has high tensile strength more than 1280MPa and guaranteed ductility.
The > such as < temper rolling
The steel plate that obtains of operation can carry out the temper rolling for reconciliation statement surface roughness as required like this, or for plating and the chemical conversion processing of antirust Zn, Ni etc.
< compression moulding >
The steel plate obtaining by manufacture method of the present invention, although the starting material that can use as compression moulding use, is very different with the intensity area of general cold-rolled steel sheet, therefore, need to consider sprung back etc.
Embodiment
In order to further describe cold-rolled steel sheet of the present invention with embodiment and comparative example, prepare the slab sheet of composition shown in the test portion 1～18 shown in table 1.Test portion 1～11,17,18 for entering the slab sheet of composition range of the present invention, and test portion 12～16 is the slab sheet outside composition range of the present invention.
In hot-rolled process, the slab sheet that is adjusted into composition shown in test portion 1～18 is heated to 1230 DEG C, at the coiling temperature shown in table 2, manufacture the hot-rolled steel sheet of thickness of slab 2.0mm.The property list of this hot-rolled steel sheet is shown in to table 2.
Then, after this hot-rolled steel sheet of pickling, being cold-rolled to 0.5mm, then, in continuous annealing operation, is that 900 DEG C of soaking keep after 20s making soaking temperature, carries out coolingly with 20 DEG C/s of speed of cooling, makes cold-rolled steel sheet.The property list of this cold-rolled steel sheet is shown in to table 2.
As shown in Table 2, in embodiment 1～15, the tensile strength of hot-rolled steel sheet is below 1000MPa, in thereafter cold rolling, can be thinned to the 0.5mm as target thickness, and the tensile strength that can make cold-rolled steel sheet is more than 1280MPa, it is more than 3% making elongation at break.
In addition, in embodiment 3,4, make speed of cooling after soaking be changed to respectively 3 DEG C/s, 100 DEG C/s, can obtain having respectively the tensile strength, 6.2% of 1320MPa, 1405MPa, the cold-rolled steel sheet of 6.0% elongation at break.
Comparative example 1 composition identical with embodiment 1 of serving as reasons, it is the hot-rolled steel sheet that test portion 1 is manufactured, due to coiling temperature is reduced to 480 DEG C, the tensile strength of hot-rolled steel sheet is increased to 1108MPa, due to harder, in thereafter cold rolling, can not be thinned to the 0.5mm as target thickness, while making the load of rolling increase and make rolling increased frequency, crack, therefore, end cold rolling.
The hot-rolled steel sheet of comparative example 2 is by the composition identical with embodiment 2～4, it is the hot-rolled steel sheet that test portion 2 is manufactured, due to coiling temperature is reduced to 500 DEG C, the tensile strength of hot-rolled steel sheet is increased to 1216MPa, due to harder, in thereafter cold rolling, can not be thinned to the 0.5mm as target thickness, while making the load of rolling increase and make rolling increased frequency, crack, therefore, end cold rolling.
In comparative example 3,4, C is below 0.10, and in comparative example 5, Cr is below 1.2%, in comparative example 7, Mn and Ni are few, therefore Mn+Ni is below 0.5%,, the tensile strength of cold-rolled steel sheet becomes respectively below 1280MPa, as gasket and frame parts use in the situation that, undercapacity, not applicable.
In comparative example 6, the total content of Mn+Ni increases to 3.4, and therefore, the tensile strength of hot-rolled steel sheet improves, and in thereafter cold rolling, can not be rolled down to the 0.5mm as target thickness.Particularly, even if rolling due to more firmly can not attenuation, or cracks in the time that the load that makes rolling increases and makes rolling increased frequency, can not produce.
[table 1]
[table 2]
Utilizability in industry
According to the present invention, a kind of load alleviating when cold rolling can be provided, high strength and guaranteed the cold-rolled steel sheet of the compression moulding excellence of ductility, can provide a kind of desired thickness of starting material having as liquid crystal frame or the frame parts etc. of the petrolic gasket for automobile, notebook computer, mobile telephone, digital camera: 0.05mm～0.6mm, tensile strength: 1280MPa is above, elongation at break: cold-rolled steel sheet more than 3%, that simultaneously possess intensity and processibility, the utilizability in industry is high.
Claims (4)
1. a manufacture method for cold-rolled steel sheet, is characterized in that,
To by Heating temperature being made as more than 1100 DEG C, it is that hot-rolled steel sheet below 1000MPa carries out after pickling that coiling temperature is made as 600～800 DEG C of tensile strength of carrying out hot-rolled process and obtain, the rate of being rolled adds up to more than 60% cold rolling, make cold-rolled steel sheet, soaking temperature is set as more than 750 DEG C, speed of cooling is set as 3 DEG C/s～100 DEG C/s, carry out final continuous annealing processing, in final continuous annealing is processed, the soaking of carrying out above below the above 100s of 1s with 750 DEG C of soaking temperatures keeps, it is more than 1280MPa making tensile strength, elongation at break is more than 3%, thickness is the cold-rolled steel sheet of 0.05～0.60mm, wherein, described hot-rolled steel sheet comprises following composition in quality %:
C：0.10～0.30、
More than Mn:0.2,
More than Ni:0.01,
Mn＋Ni：0.5～2.5、
Cr：1.2～9.0，
Remainder is iron and inevitable impurity.
2. the manufacture method of cold-rolled steel sheet claimed in claim 1, is characterized in that, the thickness of described hot-rolled steel sheet is 1.2～3.0mm.
3. a cold-rolled steel sheet, is characterized in that,
To by Heating temperature being made as more than 1100 DEG C, it is that hot-rolled steel sheet below 1000MPa carries out after pickling that coiling temperature is made as 600～800 DEG C of tensile strength of carrying out hot-rolled process and obtain, the rate of being rolled adds up to more than 60% cold rolling, make cold-rolled steel sheet, soaking temperature is set as more than 750 DEG C, speed of cooling is set as 3 DEG C/s～100 DEG C/s, carry out final continuous annealing processing, in final continuous annealing is processed, the soaking of carrying out above below the above 100s of 1s with 750 DEG C of soaking temperatures keeps, it is more than 1280MPa making tensile strength, elongation at break is more than 3%, thickness is the cold-rolled steel sheet of 0.05～0.60mm, wherein, described hot-rolled steel sheet comprises following composition in quality %:
C：0.10～0.30、
More than Mn:0.2,
More than Ni:0.01,
Mn＋Ni：0.5～2.5、
Cr：1.2～9.0，
Remainder is iron and inevitable impurity.
4. cold-rolled steel sheet claimed in claim 3, the thickness of described hot-rolled steel sheet is 1.2～3.0mm.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2009-162198 | 2009-07-08 | ||
| JP2009162198 | 2009-07-08 | ||
| PCT/JP2010/004062 WO2011004554A1 (en) | 2009-07-08 | 2010-06-17 | Process for production of cold-rolled steel sheet having excellent press moldability, and cold-rolled steel sheet |
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| CN102471821A CN102471821A (en) | 2012-05-23 |
| CN102471821B true CN102471821B (en) | 2014-07-16 |
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| US (1) | US20120234438A1 (en) |
| EP (1) | EP2455499B1 (en) |
| JP (1) | JP5717631B2 (en) |
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| CN103849820B (en) * | 2014-03-19 | 2017-01-04 | 武汉钢铁(集团)公司 | The rolling mill practice of high-strength corrosion-resisting Li-adding Al alloy muscle |
| RU2017141033A (en) * | 2015-05-21 | 2019-06-21 | Ак Стил Пропертиз, Инк. | HIGH-MAGNANTIC, ESPECIALLY HIGH-STRENGTH STEELS, 3rd GENERATION |
| CN105177458A (en) * | 2015-08-31 | 2015-12-23 | 铜陵市大明玛钢有限责任公司 | Manufacturing method of cold-rolled steel plate |
| WO2020004561A1 (en) * | 2018-06-29 | 2020-01-02 | 東洋鋼鈑株式会社 | Hot-rolled steel sheet, high-strength cold-rolled steel sheet, and manufacturing methods therefor |
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| JPS5825733B2 (en) * | 1979-11-27 | 1983-05-30 | 新日本製鐵株式会社 | Method for manufacturing high-strength cold-rolled steel sheet with good paintability, weldability, and workability |
| JP3254107B2 (en) * | 1995-05-19 | 2002-02-04 | 株式会社神戸製鋼所 | Ultra-high-strength steel sheet excellent in delayed fracture resistance and method of manufacturing the same |
| JP3254106B2 (en) | 1995-05-19 | 2002-02-04 | 株式会社神戸製鋼所 | Ultra-high-strength steel sheet excellent in hydrogen embrittlement resistance and method for producing the same |
| JPH09194935A (en) | 1996-01-10 | 1997-07-29 | Toyo Kohan Co Ltd | Production of cold rolled steel sheet for gasket material, excellent in spring characteristic, and gasket material |
| JPH101740A (en) * | 1996-06-12 | 1998-01-06 | Kobe Steel Ltd | Ultrahigh strength steel sheet excellent in delayed fracture resistance, and its production |
| JP3958921B2 (en) * | 2000-08-04 | 2007-08-15 | 新日本製鐵株式会社 | Cold-rolled steel sheet excellent in paint bake-hardening performance and room temperature aging resistance and method for producing the same |
| TWI290177B (en) * | 2001-08-24 | 2007-11-21 | Nippon Steel Corp | A steel sheet excellent in workability and method for producing the same |
| JP4288201B2 (en) * | 2003-09-05 | 2009-07-01 | 新日本製鐵株式会社 | Manufacturing method of automotive member having excellent hydrogen embrittlement resistance |
| ES2391164T3 (en) * | 2003-09-30 | 2012-11-22 | Nippon Steel Corporation | Thin sheet of cold rolled steel, high strength, with high limit of elasticity, and superior ductility and weldability, thin sheet of hot dipped galvanized steel, high strength, with high limit of elasticity, thin sheet of galvanized steel and hot dipped annealing, high strength, with high limit of eleasticity, and methods for their production |
| JP4639996B2 (en) * | 2004-07-06 | 2011-02-23 | 住友金属工業株式会社 | Manufacturing method of high-tensile cold-rolled steel sheet |
| JP2007016296A (en) * | 2005-07-11 | 2007-01-25 | Nippon Steel Corp | Steel sheet for press forming with excellent ductility after forming, its forming method and automotive parts using the steel sheet for press forming |
| JP5194878B2 (en) * | 2007-04-13 | 2013-05-08 | Ｊｆｅスチール株式会社 | High-strength hot-dip galvanized steel sheet excellent in workability and weldability and method for producing the same |
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- 2010-06-17 US US13/383,193 patent/US20120234438A1/en not_active Abandoned
- 2010-06-17 EP EP10796868.7A patent/EP2455499B1/en active Active
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| JP特开平8-311601A 1996.11.26 |
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| US20120234438A1 (en) | 2012-09-20 |
| EP2455499B1 (en) | 2017-12-13 |
| EP2455499A1 (en) | 2012-05-23 |
| JP5717631B2 (en) | 2015-05-13 |
| WO2011004554A1 (en) | 2011-01-13 |
| EP2455499A4 (en) | 2016-02-10 |
| CN102471821A (en) | 2012-05-23 |
| JPWO2011004554A1 (en) | 2012-12-13 |
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