CN102449178A - Hot rolled sheet steel having excellent formability, and method for producing same - Google Patents
Hot rolled sheet steel having excellent formability, and method for producing same Download PDFInfo
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- CN102449178A CN102449178A CN201080022678XA CN201080022678A CN102449178A CN 102449178 A CN102449178 A CN 102449178A CN 201080022678X A CN201080022678X A CN 201080022678XA CN 201080022678 A CN201080022678 A CN 201080022678A CN 102449178 A CN102449178 A CN 102449178A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 87
- 239000010959 steel Substances 0.000 title claims abstract description 87
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 238000005096 rolling process Methods 0.000 claims description 35
- 238000001816 cooling Methods 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 11
- 238000005098 hot rolling Methods 0.000 claims description 6
- 230000032683 aging Effects 0.000 abstract description 20
- 239000013078 crystal Substances 0.000 abstract description 6
- 238000005516 engineering process Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 230000035882 stress Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 238000012360 testing method Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000007669 thermal treatment Methods 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 241000345998 Calamus manan Species 0.000 description 1
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000003450 growing effect Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 239000010985 leather Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 235000012950 rattan cane Nutrition 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 229910000859 α-Fe 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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- 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
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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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 hot rolled sheet steel which has aging resistance and soft/highly ductile properties, while achieving improved Delta r without causing excessive grain coarsening; and a method for producing the hot rolled sheet steel. Specifically disclosed is a hot rolled sheet steel which is characterized by containing, in mass%, not less than 0.03% but not more than 0.07% of C, not more than 0.1% of Si, not less than 0.05% but not more than 0.5% of Mn, not more than 0.03% of P, not more than 0.03% of S, not less than 0.02% but not more than 0.1% of sol. Al, not more than 0.005% of N, less than 0.005% of Nb + Ti and not less than 0.0003% but not more than 0.0020% of B, with the balance made up of Fe and unavoidable impurities. The hot rolled sheet steel is also characterized by having an average crystal grain size of not less than 12 [mu]m but not more than 25 [mu]m, while satisfying Delta r = 0.25 and AI = 20 MPa.
Description
Technical field
The present invention relates to be applicable to the raw-material hot-rolled steel sheet of automobile, tame electrical article etc., relate to have the processibility that is suitable for drawing etc. and ageing resistance, the also good hot-rolled steel sheet of intra-face anisotropy.
Background technology
Hot-rolled steel sheet for being used in automobile, electrical apparatus product etc. requires high formability, is for the hot-rolled steel sheet that uses of the deep drawing punching press purposes of representative for being used for the compressor shroud particularly, is devoted to advance softization and high ductibilityization.In addition,, follow the time of delivery of goods and storage time to change for a long time, also more and more pay attention to the stability of material, particularly ageing resistance along with the globalization of present production base.
Deep drawing about ageing resistance is good is used hot-rolled steel sheet; Patent documentation 1 has proposed following technology; Promptly guarantee soft high ductibility, and fix the N in the steel, thereby improve ageing resistance through the B that adds more than 0.001% through the upper limit that limits strengthening elements such as C, Mn.But, therefore in this technology, because the B addition has produced as the index of the intra-face anisotropy of expression pull and stretch processing up to more than 0.001% in the hot rolled steel plate | the problem that Δ r| (anisotropy of r value poor (different variance)) increases.
For the problems referred to above of finding at the hot-rolled steel sheet that has added B, patent documentation 2 has proposed through regulation B addition and with Ar
3High temperature more than point+20 ℃ carries out finish to gauge and improves | the technology of Δ r|.In addition, be not the hot-rolled steel sheet that has added B for the hot-rolled steel sheet of having stipulated P content, in order to improve hot-rolled steel sheet | Δ r|, patent documentation 3 has proposed at Ar
3Carry out finish to gauge more than the point.
But disclosed like non-patent literature 1, the hot-rolled steel sheet that has added B is easy to become coarse grain, and high to the interdependence of hot rand spare.Therefore, if as patent documentation 2 and patent documentation 3 proposed just carry out finish to gauge with high temperature, excessive coarse then, thus the generation of the surface after drawing is coarse.In addition; The hot-rolled steel sheet that patent documentation 3 is proposed does not add B, but owing to through being set to extremely low P (below 0.005%) grain growing property is increased, therefore; The hot-rolled steel sheet that is proposed with patent documentation 2 is identical, and existence is followed excessive coarse and shaggy problem is taken place.
On the other hand, in patent documentation 4, be that purpose discloses the technology of in hot-rolled steel sheet, adding Ti, Nb to suppress the over-drastic grain growing.But the recrystallize of Ti, Nb suppresses effect and grain growing inhibition effect is obviously stronger.Therefore, in order to improve the hot-rolled steel sheet that added Ti, Nb | Δ r| and guarantee the crystallization particle diameter of appropriateness need keep long-time in the high temperature territory.In addition, in patent documentation 4 disclosed technology,, therefore can't avoid generation, also have the problem of ageing resistance variation in the timeliness in low C territory owing to do not add B.
The prior art document
Patent documentation
Patent documentation 1: japanese kokai publication sho 52-125411 communique
Patent documentation 2: japanese kokai publication hei 2-209423 communique
Patent documentation 3: japanese kokai publication hei 2-209424 communique
Patent documentation 4: japanese kokai publication hei 2-30713 communique
Non-patent literature
Non-patent literature 1: mediocre, other 3 of her rattan, " about hot rolled steel plate for punch process KFN ", Kawasaki Steel skill newspaper, Kawasaki Steel Corp,, Vol.5 No.2, Pg.224-234 in 1973
Summary of the invention
Invent problem to be solved
As stated, use hot-rolled steel sheet for deep drawing, though disclose several kinds of improvement | the technology of Δ r|, these technology are because the subsidiary problems such as shaggy generation, ageing resistance variation that produce still have room for improvement.The present invention is in view of this situation and accomplishing, and its purpose is to provide a kind of not only plasticity and ageing resistance good and improved | Δ r| and the soft hot-rolled steel sheet of excessive coarse and favourable method of manufacture thereof do not take place.
The method that is used to deal with problems
The inventor is in order to solve above-mentioned problem, and the recrystallize characteristic and the grain growing characteristic of the aluminium killed steel that adds B are furtherd investigate repeatedly.Its result obtains following new discovery; Promptly; One-tenth through the control steel is grouped into, the cooling conditions after finishing temperature and rolling rate and the finish to gauge etc., and is special, adds P through more amount on composition; And on operation, finish the deepfreeze of putting that the short period of time is implemented in the back, thereby can in the hot-rolled steel sheet that possesses ageing resistance and soft high ductibility, reduce in hot rolling | Δ r| and do not cause excessive coarse as the reason of surface irregularity etc.
The present invention is based on above-mentioned opinion and accomplish, its main points are following.
(1) a kind of hot-rolled steel sheet; It is characterized in that; In quality %; Contain: C:0.03% above and 0.07% below, below the Si:0.1%, Mn:0.05% is above and 0.5% below, P:0.01% is above and 0.03% below, below the S:0.03%, Sol.Al:0.02% is above and 0.1% below, below the N:0.005%, Nb+Ti: less than 0.005% and more than the B:0.0003% and below 0.0020%, surplus is made up of Fe and unavoidable impurities, and the average crystallite particle diameter is that 12 μ m are above and below the 25 μ m; And, | Δ r|≤0.25, AI≤20MPa.
(2) a kind of method of manufacture of hot-rolled steel sheet is characterized in that, in rolling temperature: compare Ar
3Point is high more than 50 ℃ and rolling rate: under the condition more than 15%; Steel disc is implemented the final passage of hot rolled; After this hot rolling finishes; Put cold more than 0.5 second and the time below 10 seconds; Be cooled to below 700 ℃ with the above speed of cooling of 20 ℃/s then, and batching more than 590 ℃ and below 700 ℃, wherein; Said steel disc contains in quality %: C:0.03% above and 0.07% below, below the Si:0.1%, Mn:0.05% is above and 0.5% below, P:0.01% is above and 0.03% below, below the S:0.03%, Sol.Al:0.02% is above and 0.1% below, below the N:0.005%, Nb+Ti: less than 0.005% and more than the B:0.0003% and below 0.0020%, surplus is made up of Fe and unavoidable impurities.
The invention effect
According to the present invention, for hot-rolled steel sheet, can give sufficient ageing resistance and soft high ductibility, and, can when keeping the crystallization particle diameter that is suitable for punch process, reduce intra-face anisotropy.Therefore, according to hot-rolled steel sheet of the present invention, the goods of the high processing of needs of difficulty even compressor shroud etc. are shaped for existing hot-rolled steel sheet also can be made and when being shaped, can't cause the quality variation that is caused by surface irregularity etc.
Embodiment
Below, one-tenth of the present invention is grouped into and the qualification reason of creating conditions describes.Need to prove that the unit of the content of the element in the steel plate is " quality % ", below, short of special instruction is only represented with " % ".
(1) composition compositing range
More than the C:0.03% and below 0.07%
If C content is many, then generate carbide in a large number, the extensibility of hot-rolled steel sheet is reduced and the obstruction plasticity, therefore, making its content is below 0.07%.On the other hand, extremely low Cization will cause the increase of manufacturing cost, therefore make under it to be limited to 0.03%.
Below the Si:0.1%
If Si is excessive containing, and then improves intensity and makes the plasticity variation, and therefore making its content is below 0.1%.Among the present invention, Si is the element that makes the plasticity variation, and preferably its content is low more good more.
More than the Mn:0.05% and below 0.5%
Thereby the form that Mn has with MnS fixes the effect that S improves high-temperature ductility, and therefore, need make its content is more than 0.05%.On the other hand, excessive interpolation can cause the hardization of steel, and makes the plasticity variation, therefore make its content on be limited to 0.5%.
More than the P:0.01% and below 0.03%
P is the characteristic element among the present invention.That is, if P content is few, then grain growing is increased, and causes being improved by the shaggy possibility that coarse causes.Therefore, among the present invention, contain 0.01% P at least.Though P is the solution strengthening element, as if excessive containing, then can cause the hardization of steel, therefore make to be limited to 0.03% on it.
Below the S:0.03%
S is the element that hinders high-temperature ductility, plasticity, and preferably its content is low.In addition, with improve high-temperature ductility, plasticity is a purpose, S is fixed with the form of MnS, but if the excessive extensibility that then can cause of MnS amount reduces, therefore make S content on be limited to 0.03%.
More than the sol.Al:0.02% and below 0.1%
Al not only plays a role as reductor, also with the form fix of AlN not by B fixed N, thereby improve ageing resistance.As the content of sol.Al, need be for more than 0.02%.On the other hand, over-drastic adds will cause the manufacturing cost rising, therefore make to be limited to 0.1% on it.
Below the N:0.005%
N is the element of reason that constitutes the timeliness of hot-rolled steel sheet, and preferably its content is few more good more, and still, excessively reduction can cause significant cost to rise.Among the present invention, fix N through adding B and Al, therefore as long as N content is just can ignore its detrimentally affect below 0.005%, therefore making on it is 0.005%.
Nb+Ti: less than 0.005%
Nb, Ti are that powerful recrystallize suppresses element, therefore if excessively contain these elements, then are difficult to make | Δ r| reduces.In addition, these elements also are that powerful grain growing suppresses element, and therefore the crystal grain of hot-rolled steel sheet becomes particulate if excessively contain then, thereby causes ductile reduction.At this on the one hand, preferred Nb+Ti amount is few more good more, but if the content of Nb and Ti amounts to less than 0.005%, then can ignore above-mentioned detrimentally affect, thus make Nb+Ti on be limited to less than 0.005%.
More than the B:0.0003% and below 0.0020%
Thereby the element that B is a fix N improves ageing resistance.In addition, it has the effect that makes crystal grain appropriateness coarse, thus the effect of the ductile reduction that performance suppresses to be caused by the crystal grain miniaturization, therefore, and as the content of B, need be for more than 0.0003%.On the other hand, if excessively add, then | Δ r| increases, and therefore makes to be limited to 0.0020% on it.
Need to prove that the surplus beyond the mentioned component is Fe and unavoidable impurities.As impurity, allow the for example degree below the Cu:0.02%, below the Ni:0.02%.
(2) average crystallite particle diameter
Need make the average crystallite particle diameter is more than the 12 μ m and below the 25 μ m.This is because during less than 12 μ m, ys increases and forms the deformation difficulty, if surpass 25 μ m, then when drawing, produces surface irregularity.And, more preferably more than the 12 μ m and below the 23 μ m.
(3)|Δr|≤0.25
The anisotropy of the average r value shown in following note (1) formula is poor | and Δ r| is if surpass 0.25, and then the yield rate during drawing and forming reduces, so need be below 0.25.
| Δ r|=| (r
0+ r
90-2r
45)/2| (1) formula
Wherein, r
0The r value of expression rolling direction (RD), r
90The r value of representing rolling right angle orientation (TD), r
45The r value of representing rolling 45 ° of directions (DD).In addition, from reducing the shaping load aspect, preferably making average r value is more than 0.80.And steel plate of the present invention is a hot-rolled steel sheet, and average r value is approximately below 1.0.
(4)AI≤20MPa
Ageing index AI is meant after the stretching of elongation 7.5%, and the tensile stress of under 100 ℃, carrying out before and after 30 minutes the ageing treatment is poor.Need to prove, after the ageing treatment, owing to occur the yield extension phenomenon sometimes, lower yield stress and 0.2% ys after therefore strictly Use Limitation is handled.If ageing index AI surpasses 20Mpa, then material changes in carrying the way or between the coiled material maintaining period, thereby needs to realize the optimization of drawing condition, therefore causes the rising of goods cost.Relative with it, if AI is below the 20MPa, then be in the scope that the material variation issue does not take place, therefore making AI is below the 20MPa, more preferably below the 10MPa.
(5) manufacturing process
Steel to melting is adjusted in the mentioned component compositing range is cast, thereby obtains steel disc, behind just casting back or reheat, in rolling temperature: compare Ar
3Point is high more than 50 ℃ and rolling rate: under the condition more than 15% above-mentioned steel disc is carried out the final passage of hot rolled; After this hot rolling finishes; Put cold more than 0.5 second and the time below 10 seconds; Be cooled to below 700 ℃ with the above speed of cooling of 20 ℃/s then, batching more than 590 ℃ and below 700 ℃.Need to prove that above-mentioned reheat temperature does not need special stipulation, but need carry out reheat, be generally 1050～1300 ℃ with the condition that can guarantee finishing temperature.
Like the present invention,,, importantly realize cooling conditions and the optimization of coiling temperature after finishing temperature and rolling rate, the finish to gauge in order when keeping the crystallization particle diameter that is suitable for punch process, to reduce intra-face anisotropy for the hot-rolled steel sheet that has added B.
The inventor is to having as above the hot-rolled steel sheet that contains B formed | and the dependency of the rolling temperature of Δ r| and the final passage of hot rolled is investigated.Need to prove that at this, the final passage of hot rolled is meant the final passage in the hot rolled finish to gauge, promptly final rolling support, rolling temperature (being also referred to as finishing temperature) is the outgoing side temperature of this rolling stand.Its result shows, along with the rolling temperature of final passage from Ar
3Point beginning high temperatureization, hot-rolled steel sheet | Δ r| reduces, when becoming Ar
3In the time of more than point+50 ℃, | Δ r| expresses the value of basic fixed.Though its reason is confirmed, infer as follows, be Ar in the final rolling temperature of passage
3Under near the point the situation, the r in above-mentioned (1) formula
45Value shows and compares r
0Value and r
90Be worth big value, along with the rolling temperature high temperatureization of final passage, r
0Value and r
90Value rises, on the other hand r
45Value descends, and its result does, in above-mentioned (1) formula | Δ r| reduces, and should | the reduction effect of Δ r| is at Ar
3Saturated during point+50 ℃.
Therefore, among the present invention, in order to realize reducing | Δ r| is being made as rolling temperature with final passage: Ar
3Carry out finish to gauge under the high temperature more than point+50 ℃.Wherein, from reducing the oxide debris aspect, preferably making finishing temperature is below 950 ℃.In addition, after finish to gauge, put the cold scheduled time among the present invention.This be for make the austenite worked structure that forms by finish to gauge in the austenitic area recrystallize and make the texture randomization, thereby realize reducing | Δ r|.At this, if putting after the finish to gauge is cold less than 0.5 second, then because recrystallizing of austenite worked structure is also insufficient, therefore making the above-mentioned cool time of putting in the present invention is more than 0.5 second.
As stated, if at high temperature carry out finish to gauge, put for a long time afterwards cold, though then | Δ r| diminishes, and can cause forming as the over-drastic coarse grain of the characteristic of the steel that adds B, thereby cause the surface irregularity of drawing article.In order to address this problem; Make the rolling rate of final passage (the rolling rate of final passage) be more than 15%, more preferably carry out more than 20%; Increase the recrystallize check figure, and then to make the cool time of putting after the finish to gauge be below 10 seconds, preferably less than 5 seconds, thereby suppress the grain growing of austenite grain; Thus, the size with the crystal grain behind the ferrite transformation is adjusted into suitable scope.
Need to prove,, preferably make the rolling rate less than 25% from making the good aspect of steel plate shape.
, be cooled to below 700 ℃ with the speed of cooling more than 20 ℃/second, and batching more than 590 ℃ and below 700 ℃ after the time through predetermined maintenance (putting cold).For the grain growing in suppressing to cool off, need make speed of cooling is more than 20 ℃/second.In addition, if coiling temperature surpasses 700 ℃, then cause the surface texture variation by the oxide debris that generates in batching, less than 590 ℃ the time, AI surpasses 20MPa, thereby the material in causing carrying, in the keeping changes.Therefore, making coiling temperature is more than 590 ℃ and below 700 ℃.Be preferably more than 625 ℃.Need to prove that the viewpoint of never following manufacturing cost significantly to rise is set out, the upper limit of above-mentioned speed of cooling is roughly about 500 ℃/second.
No matter hot-rolled steel sheet of the present invention is for the pickling material still is the casting skin material, and its performance is constant.In addition, after the pickling or omitted pickling De ?leather material directly carry out pot galvanize and also have no problem.To the not restriction of condition of temper rolling, but if unit elongation is too high, then the extension property of steel reduces, and therefore preferably making the unit elongation of temper rolling is below 2%.
In addition, the present invention is a yielding stress as the hot-rolled steel sheet of object: about 250MPa is following, thickness of slab: the above and soft hot-rolled steel sheet below about 6mm, that be applicable to the deep drawing purposes of about 2mm.
Embodiment
(embodiment 1)
Steel to having composition shown in the table 1 carries out melting; Be cut into hot-work simulation (the processing Off オ one マ ス タ) test film of φ 8mm, height 12mm; Be heated to 1200 ℃; Be cooled to 950 ℃ with 10 ℃/second speed of cooling then, the strain with 30% under 950 ℃ is compressed, and is cooled to 200 ℃ with 10 ℃/second speed of cooling then.Thermal expansion curve determination Ar during according to cooling
3Point is 823 ℃.After this steel is heated to 1200 ℃, under the condition shown in the table 2, carry out hot rolling, process the hot-rolled steel sheet of thickness of slab 3.2mm.
After the hot-rolled steel sheet pickling that obtains, implement the temper rolling of unit elongation 1%, carry out mechanical characteristics evaluation, structure observation.For mechanical characteristics, cut No. 5 test films of JIS Z 2201 (1998) along rolling direction (RD), carry out tension test according to JIS Z 2241 (1998).
For the r value, cut No. 5 test films of JIS Z 2201 (1998) along rolling direction (RD), rolling right angle orientation (TD), rolling 45 ° of directions (DD), give 15% strain and measure.And, according to above-mentioned (1) formula, obtain | Δ r|.
For AI; Cut No. 5 test films of JIS Z 2201 (1998) along rolling direction (RD); After giving 7.5% prestrain, under 100 ℃, carry out thermal treatment in 30 minutes, estimate through the difference of the yielding stress after stress before the thermal treatment (stress when 7.5% prestrain is given) and the thermal treatment.
In addition, the rolling direction section structure is carried out the nital corrosion, measure the average crystallite particle diameter according to the patterning method that JIS G 0552 (1998) is put down in writing in thickness of slab 1/4 position.The result is illustrated in table 2 in the lump.
Condition B, C, G, the H of example according to the present invention; Can obtain the less hot-rolled steel sheet of anisotropy; And the yielding stress YP of this hot-rolled steel sheet is that 220MPa is following, ultimate elongation rate El is more than 48%, thereby has soft high ductibility, and; AI is below the 20MPa, | Δ r| is below 0.25, thereby has sufficient ageing resistance.In addition, the average crystallite particle diameter of the hot-rolled steel sheet that the condition B of example, C, G, H make according to the present invention satisfies the scope of 12～25 μ m, the shaggy problem in the time of therefore can drawing not occurring.And can know that coiling temperature is more than 625 ℃ among the condition B of the present invention's example, C, the H, and the AI of the hot-rolled steel sheet that therefore obtains is below the 10MPa, ageing resistance is good especially.
On the other hand; Under the less condition I of the rolling rate of the lower condition E of the rolling temperature of putting the short condition A of cool time, the final passage of finish to gauge, K, the final passage of finish to gauge; The recrystallize of austenitic area does not fully carry out; Therefore, the anisotropy of the hot-rolled steel sheet of making according to these conditions is higher, causes | and Δ r| has surpassed 0.25.In addition, for for the hot-rolled steel sheet of putting the slower condition J manufacturing of cool time long condition D, speed of cooling, it is thick that crystal grain becomes.In addition, the AI that is lower than the hot-rolled steel sheet that 590 ℃ condition F makes according to coiling temperature has surpassed 20MPa.
(embodiment 2)
Steel to having composition shown in the table 3 carries out melting, according to measuring Ar with embodiment 1 identical method
3The point.Then, after these steel were heated to 1200 ℃, the final passage of under 875 ℃ of rolling rates 22%, temperature, carrying out the finish to gauge in the hot rolling was put after finish to gauge cold 4.2 seconds, was cooled to 630 ℃ with 25 ℃/second speed of cooling, directly batched.
According to the method identical, the heat that obtains is prolonged the mensuration that plate carries out mechanical characteristics, r value, AI, average crystallite particle diameter with embodiment 1.The result is illustrated in table 3 in the lump.
Table 3-2
According to satisfying the grade of steel 3,4 that one-tenth of the present invention is grouped into; Can obtain the less hot-rolled steel sheet of anisotropy; And the yielding stress YP of this hot-rolled steel sheet is that 220MPa is following, ultimate elongation rate El is more than 48%, thereby has soft high ductibility, and; AI is below the 20MPa, | Δ r| is below 0.25, thereby has sufficient ageing resistance.In addition, the hot-rolled steel sheet of grade of steel 3, because the average crystallite particle diameter is below the 20 μ m, therefore shaggy possibility is littler.
On the other hand, for C measured more grade of steel 2, the average crystallite grain of hot-rolled steel sheet was that particulate and ys increase.For P measured less grade of steel 5, the average crystallite grain of hot-rolled steel sheet became thick.For the more grade of steel 8 of the more grade of steel 6 of Nb, Ti amount and B amount, because the recrystallize of austenitic area fully do not carry out, so the anisotropy of hot-rolled steel sheet is higher, thereby | Δ r| surpasses 0.25.In addition, in the less grade of steel 7 of B amount, the AI of hot-rolled steel sheet has surpassed 20MPa.
Utilizability on the industry
According to the present invention; Through the processing of having added B is added P with hot-rolled steel sheet in 0.01～0.03% scope; And with rolling rate: carry out final passage more than 15%; 0.5～10 second the deepfreeze of putting is set then, can obtains having ageing resistance and soft high ductibility thus and improved | Δ r| and do not produce the hot-rolled steel sheet of excessive coarse.
Claims (2)
1. hot-rolled steel sheet; It is characterized in that; In quality %; Contain: C:0.03% above and 0.07% below, below the Si:0.1%, Mn:0.05% is above and 0.5% below, P:0.01% is above and 0.03% below, below the S:0.03%, Sol.Al:0.02% is above and 0.1% below, below the N:0.005%, Nb+Ti: less than 0.005% and more than the B:0.0003% and below 0.0020%, surplus is made up of Fe and unavoidable impurities, and the average crystallite particle diameter is that 12 μ m are above and below the 25 μ m; And, | Δ r|≤0.25, AI≤20MPa.
2. the method for manufacture of a hot-rolled steel sheet is characterized in that, in rolling temperature: compare Ar
3Above and the rolling rate of the temperature that point is high 50 ℃: under the condition more than 15%; Steel disc is implemented the final passage of hot rolled; After this hot rolling finishes; Put cold more than 0.5 second and the time below 10 seconds; Be cooled to below 700 ℃ with the above speed of cooling of 20 ℃/s then, and batching more than 590 ℃ and below 700 ℃, wherein; Said steel disc contains in quality %: C:0.03% above and 0.07% below, below the Si:0.1%, Mn:0.05% is above and 0.5% below, P:0.01% is above and 0.03% below, below the S:0.03%, Sol.Al:0.02% is above and 0.1% below, below the N:0.005%, Nb+Ti: less than 0.005% and more than the B:0.0003% and below 0.0020%, surplus is made up of Fe and unavoidable impurities.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2009125465A JP5407552B2 (en) | 2009-05-25 | 2009-05-25 | Hot-rolled steel sheet with excellent formability and manufacturing method thereof |
| JP2009-125465 | 2009-05-25 | ||
| PCT/JP2010/058847 WO2010137598A1 (en) | 2009-05-25 | 2010-05-19 | Hot rolled sheet steel having excellent formability, and method for producing same |
Publications (2)
| Publication Number | Publication Date |
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| CN102449178A true CN102449178A (en) | 2012-05-09 |
| CN102449178B CN102449178B (en) | 2014-12-10 |
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| CN201080022678.XA Expired - Fee Related CN102449178B (en) | 2009-05-25 | 2010-05-19 | Method for producing hot rolled sheet steel having excellent formability |
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| Country | Link |
|---|---|
| JP (1) | JP5407552B2 (en) |
| KR (1) | KR101369098B1 (en) |
| CN (1) | CN102449178B (en) |
| MY (1) | MY153088A (en) |
| SG (1) | SG194424A1 (en) |
| WO (1) | WO2010137598A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103614617A (en) * | 2013-11-08 | 2014-03-05 | 首钢总公司 | Steel for motor turbine of roller washing machine and production method thereof |
| CN107641762A (en) * | 2017-09-26 | 2018-01-30 | 武汉钢铁有限公司 | 340MPa levels have the Hot Rolling Automobile structural steel and iron and manufacture method of excellent cold forming capability |
| CN107723607A (en) * | 2017-09-26 | 2018-02-23 | 武汉钢铁有限公司 | 420MPa levels have the Hot Rolling Automobile structural steel and iron and manufacture method of excellent cold forming capability |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5534112B2 (en) * | 2011-12-08 | 2014-06-25 | Ｊｆｅスチール株式会社 | Hot-rolled steel sheet for cold rolling material and manufacturing method thereof |
| JP2015137422A (en) * | 2014-01-24 | 2015-07-30 | Ｊｆｅスチール株式会社 | Hot rolled steel sheet and production method thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10219388A (en) * | 1997-02-05 | 1998-08-18 | Nkk Corp | Steel sheet excellent in workability and minimal in fluctuation in workability in width direction and its production |
| JPH1161270A (en) * | 1997-08-26 | 1999-03-05 | Nkk Corp | Manufacture of hot rolled steel sheet minimal in plastic anisotropy and excellent in workability |
| CN1366558A (en) * | 2000-02-23 | 2002-08-28 | 川崎制铁株式会社 | High tensile hot-rolled steel sheet having excellent strain aging hardening properties and method for producing same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10183255A (en) * | 1996-12-20 | 1998-07-14 | Nippon Steel Corp | Production of hot rolled steel sheet small in plane anisotropy of r value |
| JP3728911B2 (en) * | 1998-01-31 | 2005-12-21 | Ｊｆｅスチール株式会社 | Raw material for surface-treated steel sheet having excellent aging resistance and low ear occurrence rate, and method for producing the same |
-
2009
- 2009-05-25 JP JP2009125465A patent/JP5407552B2/en active Active
-
2010
- 2010-05-19 CN CN201080022678.XA patent/CN102449178B/en not_active Expired - Fee Related
- 2010-05-19 MY MYPI2011005701 patent/MY153088A/en unknown
- 2010-05-19 KR KR1020117027370A patent/KR101369098B1/en active IP Right Grant
- 2010-05-19 WO PCT/JP2010/058847 patent/WO2010137598A1/en active Application Filing
- 2010-05-19 SG SG2013054267A patent/SG194424A1/en unknown
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10219388A (en) * | 1997-02-05 | 1998-08-18 | Nkk Corp | Steel sheet excellent in workability and minimal in fluctuation in workability in width direction and its production |
| JPH1161270A (en) * | 1997-08-26 | 1999-03-05 | Nkk Corp | Manufacture of hot rolled steel sheet minimal in plastic anisotropy and excellent in workability |
| CN1366558A (en) * | 2000-02-23 | 2002-08-28 | 川崎制铁株式会社 | High tensile hot-rolled steel sheet having excellent strain aging hardening properties and method for producing same |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103614617A (en) * | 2013-11-08 | 2014-03-05 | 首钢总公司 | Steel for motor turbine of roller washing machine and production method thereof |
| CN103614617B (en) * | 2013-11-08 | 2016-04-27 | 首钢总公司 | Roller washing machine Steel for motor turbine and production method thereof |
| CN107641762A (en) * | 2017-09-26 | 2018-01-30 | 武汉钢铁有限公司 | 340MPa levels have the Hot Rolling Automobile structural steel and iron and manufacture method of excellent cold forming capability |
| CN107723607A (en) * | 2017-09-26 | 2018-02-23 | 武汉钢铁有限公司 | 420MPa levels have the Hot Rolling Automobile structural steel and iron and manufacture method of excellent cold forming capability |
| CN107723607B (en) * | 2017-09-26 | 2020-02-07 | 武汉钢铁有限公司 | 420 MPa-grade hot-rolled automobile structural steel plate with excellent cold formability and manufacturing method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| KR20120022969A (en) | 2012-03-12 |
| CN102449178B (en) | 2014-12-10 |
| MY153088A (en) | 2014-12-31 |
| JP2010270383A (en) | 2010-12-02 |
| SG194424A1 (en) | 2013-12-30 |
| JP5407552B2 (en) | 2014-02-05 |
| KR101369098B1 (en) | 2014-02-28 |
| WO2010137598A1 (en) | 2010-12-02 |
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