CN102925817B - Cold-rolled steel sheet with yield strength of 980 MPa grade and manufacturing method thereof - Google Patents
Cold-rolled steel sheet with yield strength of 980 MPa grade and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses a cold-rolled steel sheet with yield strength of 980 MPa grade, and belongs to the technical field of cold-rolled high strength steel. The steel sheet comprises the following chemical components in percentage by weight: 0.08-0.13% of C, 0.05-0.5% of Si, 1.2-2.0% of Mn, less than or equal to 0.010% of P, less than or equal to 0.005% of S, 0.6-1.5% of Cr, 0.08-0.20% of Ti, 0.02-0.08% of Nb, 0.04-0.2% of V, one or more of Nb, V and Ti, 0.02-0.1% of Alt, less than or equal to 0.006% of N, less than or equal to 0.004% of O, and the balance of Fe and unavoidable impurities. The tensile strength of the steel sheet is more than 980 MPa, therefore, the steel sheet is excellent in plasticity and forming performance. The manufacturing method of the steel sheet is a low-cost cold-rolled annealed steel sheet manufacturing method, and can be implemented on common reversing cold rolling mills and cover annealing devices.
Description
Technical field
The present invention relates to a kind of yield strength and reach 980MPa level cold-rolled steel sheet and manufacture method thereof, adopted bell-type annealing processing, belong to cold rolling high-strength steel production technical field.
Background technology
Along with car safety, environmental protection, energy-conservation, the requirement of loss of weight improves constantly, and advanced high-strength steel is used extensive gradually at automotive field.In automobile manufacturing enterprise, the usage quantity of high-strength steel raises gradually, mainly for the manufacture of motor vehicle body, car floor and high-strength structure part etc., can significantly alleviate the weight of automobile, also be related in addition the stability of complete vehicle structure, shock resistance and work-ing life, service requirements and condition are very harsh.Service requirements for this type of material is mainly the high strength of steel and certain plasticity, thereby is to possess the high-intensity while, having again good shock resistance for manufactured materials requirement.
This type of traditional automobile structural steel is mainly used hot-rolled steel sheet, there is high-intensity advantage, but the control of thickness is had relatively high expectations for ordinary hot milling train, and the control difficulty of stability is larger, therefore the feature of hot-rolled sheet is to keep the thickness of high-intensity while steel plate thicker, less stable, implements and has certain difficulty.
According to the needs of automobile market, the high strength cold rolled steel plate of thin specification substitutes gradually hot-rolling high-strength steel plate and manufactures automobile structure, can play save energy, reduces costs, and improves the advantages such as intensity and work-ing life.To this, numerous patents has related to the Technology of the method manufacture high strength cold rolled steel plate that adopts different microalloyings.
It is other that publication number is that the patent of invention of CN101956139 relates to a kind of Yield strength 700 MPa grade.The method adopts the flow processs such as bar strip continuous casting and rolling flow path, cold rolling, annealing, finishing to be prepared from; Wherein, after refining, the main chemical compositions of molten steel is: C:0.03～0.07wt.%, Si :≤0.35wt.%, Mn:0.40～2.0wt.%, P :≤0.020wt.%, S≤0.010wt.%, Cr:0.25～0.80wt.%, Ti:0.06～0.25wt.%, and all the other are Fe and inevitable residual element; In described annealing process, at 500 ℃, to the temperature range of A1 transition point, described steel are annealed in bell type annealing furnace.Prepared high strength cold rolled steel plate yield strength surpasses 700MPa, and unit elongation is greater than 5%.
Publication number is that the patent of invention of CN102011060 discloses a kind of 700MPa level and has cold-rolled steel sheet of excellent weather resistance and preparation method thereof, adopt bar strip continuous casting and rolling flow path, wherein, after refining, the main chemical compositions of molten steel is: C:0.03～0.07wt.%, Si :≤0.35wt.%, Mn:0.4～1.8wt.%, P :≤0.020wt.%, S≤0.010wt.%, Cu:0.25～0.50wt.%, Cr:0.25～0.80wt.%, Ni:0.05～0.30wt.%, Ti:0.06～0.20wt.%, all the other are Fe and inevitable impurity, in described annealing process, at 500 ℃ to A
1in the temperature range of transition point, make described steel anneal in bell type annealing furnace.The yield strength with the cold-rolled steel sheet of excellent weather resistance of the present invention surpasses 700MPa, and unit elongation is greater than 5%, has good processability and good weather resistance simultaneously.
Although above-mentioned patent also adopts bell-type annealing technique, but on the one hand owing to adopting continuous casting and rolling technique of sheet bar, thickness of strand is not enough, not adding in addition Nb element causes the cold effect of control control undesirable, therefore the grain structure refinement of hot rolling stage is inadequate, causes the recrystallization crystal particle dimension of final annealing thick; In addition on the one hand because Cr content is on the low side, hardness and low strength.The factor of two aspects has caused the yield strength of cold rolled annealed state between 700MPa ~ 800MPa, does not reach the above high-intensity requirement of yield strength 980MPa.
Publication number is that the patent of invention of CN101376950 discloses a kind of cold rolling high-strength steel that Baoshan Iron & Steel Co., Ltd manufactures, a kind of superhigh intensity cold rolling weather resisting steel plate is provided, has comprised following chemical composition (wt%): C:0.09～0.16, Si:0.20～0.60, Mn:1.00～2.00, P :≤0.030, S≤0.015, N≤0.008, Al:0.02～0.06, Cu:0.20～0.40, Cr:0.40～0.60, Mo:0.05～0.25, Nb+Ti:0.04～0.08; Other is Fe and inevitable impurity.The present invention also provides the annealing temperature of this steel plate at 680 ~ 790 ℃.This steel plate provided by the invention, its yield strength 700～1000MPa, tensile strength 800～1070MPa, unit elongation 5～14%.
Publication number is that the patent of invention of CN101768695 is mentioned a kind of 1000MPa grade Ti micro-alloying ultra-fine grained cold rolling dual phase steel and preparation technology thereof, the chemical composition of steel and mass percentage content are: C:0.03 ~ 0.2%, Si:0.2 ~ 0.8%, Mn:1.2 ~ 2.0%, Ti:0.03 ~ 0.15%, S<0.015%, P<0.020%, Als:0.02 ~ 0.15%, surplus is Fe.By flexible continuous annealing process, in continuous annealing, cooling rate is less than under the condition of 50 ℃/s, can be by the size control on martensite island at 1 ~ 2 μ m or be increased to 5 about μ m, thereby obtain three kinds of dissimilar dual phase steels: high strength type (Rm:980 ~ 1200MPa, A
50: 10 ~ 13%), high-ductility sexual type (Rm:980 ~ 1100MPa, A
50: 14 ~ 18%) and comprehensive (Rm:980 ~ 1150MPa, A
50: 12 ~ 15%), yield tensile ratio is 0.47 ~ 0.65.
Above-mentioned patent annealing process is continuous annealing apparatus, and annealing temperature is high, adds Cr, after Mo, is organized as ferrite and martensite duplex structure, is therefore more prone to realize yield strength 1000Mpa.But owing to adopting two-phase steel organization, so cost increase is very large, and it is larger to realize stable control difficulty.
Above-mentioned two class patents have represented two kinds of basic ideas that realize at present high intensity cold steel rolling, have the coordination problem between intensity and cost and stability.
Cold rolling high-strength steel especially intensity higher than 700Mpa higher level other, adopt continuous annealing furnace annealing more easily to realize its mechanical property, but also have following shortcoming:
1, continuous annealing furnace facility investment is large, need to have cooling fast, the technique such as segmentation is cooling, annealing process is complicated, particularly the automatization of production line and operator is required highly, technological operation difficulty, is applicable to the anneal of the special steels such as dual phase steel more.
2, continuous annealing production line is suitable for the product that production lot is large, specification is single, can realize continuous production; For the steel grade that there is no continuous annealing apparatus or limited by continuous annealing production technique, cost increases obviously, and technique adjustment is frequent.
Along with society and expanding economy, the low-carbon economy development that Iron And Steel Industry faces, the field Lightweight Technologies such as automobile also require constantly to improve the performance of material, and material is proposed to higher requirement.This is also the trend of current ferrous materials development.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, a kind of yield strength 980MPa level cold-rolled steel sheet is provided.This steel plate not only tensile strength, more than 980MPa, and has good plasticity and forming property, can saving resource, meet the needs of different industries.
Another object of the present invention is to provide the manufacture method of above-mentioned cold-rolled steel sheet, the method is a kind of cold rolled annealed steel plate manufacture method cheaply, on common reversing cold mill and bell-type annealing equipment, just can realize.
To achieve these goals, the present invention realizes by following scheme.
Yield strength 980MPa level cold-rolled steel sheet provided by the invention, is comprised of following chemical composition by weight percentage:
C:0.08～0.13%; Si:0.05～0.5%; Mn:1.2～2.0%; P≤0.010%; S≤0.005%; Cr:0.6～1.5%; Ti:0.08～0.20%, Nb:0.02～0.08%, V:0.04～0.2%, Nb, V and Ti choose any one kind of them or are multiple; Alt:0.02 ~ 0.1%; N≤0.006%; O≤0.004%; All the other are iron Fe and inevitable impurity.
Preferably, above-mentioned cold-rolled steel sheet is comprised of following chemical composition by weight percentage: C:0.09～0.11%; Si:0.15～0.3%; Mn:1.5～1.8%; P≤0.010%; S≤0.005%; Cr:0.8～1.2%; Ti:0.08～0.16%, Nb:0.04～0.06%, V:0.04～0.1%, chooses any one kind of them in Nb, V, Ti or multiple; Alt:0.03 ~ 0.06%; N≤0.006%; O≤0.004%; All the other are iron Fe and inevitable impurity.
The yield strength of described steel plate is 980～1100MPa, and tensile strength is 1000～1200MPa, and unit elongation is 6～12%.The thickness of described steel plate is preferably 0.8-1.5mm.
The manufacture method of above-mentioned cold-rolled steel sheet is specific as follows:
Comprise smelting, refining, continuous casting, hot rolling, cold rolling, annealing operation, wherein,
In described annealing operation, the steel after adopting bell type annealing furnace to hot rolling carry out anneal, and annealing temperature is 600 ~ 720 ℃, and soaking time is 10-16h.Preferably, described annealing temperature is between 650 ~ 680 ℃, and soaking time is 12-14h.
Preferably, in described cold rolling process, the raw material through described hot-rolled process is carried out to pickling, after removal scale on surface, carry out rewinding, then on milling train, be rolled, cold rolling draft is 65%-85%.More electedly, described cold rolling draft is 70-80%, and described milling train is reversable mill, and described cold rolling draft is to complete in 8～12 passages.
Preferably, in described hot-rolled process, the continuously cast bloom that the operation by described smelting, described refining and described continuous casting is obtained is placed in process furnace, and Heating temperature is 1200～1300 ℃; Hot rolling finishing temperature is 850 ℃ ~ 900 ℃, and coiling temperature is 550 ℃ ~ 650 ℃.
Preferably, after described annealing operation, the slow cooling time is 20-30h, and more preferably, the slow cooling time is 24-26h.
The present invention compared with prior art, has following significant advantage and effect:
1, the present invention produces on common hot rolling and rolling mill production line, and hot rolling is ordinary hot equipment for continuously rolling, cold rollingly on reversable mill, carries out.Steel strength after cold rolling is high, and according to different thickness specifications, yield strength is more than 980MPa, and tensile strength is 1000～1200MPa, and unit elongation is 6～12%; The feature of this product maximum is that yield tensile ratio is higher, meets the service requirements of automobile structure.
2, adopt Nb, Ti, the microalloyings such as V, the refined crystalline strengthening successful of course of hot rolling, in cold rolling process heredity this fine grain structure, the fibrous tissue performance of generation is reasonable in the size control of annealing operation recrystal grain, realizes powerful refined crystalline strengthening effect; Adopt Ti, Nb, the microalloyings such as V, by TiC, the carbonitride Precipitations such as VC are realized precipitation strength effect; In addition, control Cr content in 1.0% left and right, improve hardness and hardening capacity, guarantee the intensity of As rolled steel band.
3, adopt bell-type annealing, can realize short run, many specifications, many variety production, annealing temperature is low, and technique is simple, workable, and cost is low.But bell-type annealing temperature needs strict guarantee between 600 ~ 720 ℃, and soaking time is controlled within the scope of 10-16h.Guarantee different ratios part recrystallized structure and and high density dislocation substructure reasonably combined, be more prone to realize different strength specification and different mechanical performance indexs.
Accompanying drawing explanation
Fig. 1 is the metallographic structure photo of the high tensile steel plate of the embodiment of the present invention 3 productions.
Embodiment
Below by embodiment, the present invention will be described.It is pointed out that embodiment, only for the invention will be further described, does not represent protection scope of the present invention, nonessential modification and adjustment that other people make according to the present invention, still belong to protection scope of the present invention.
Yield strength 980MPa level cold-rolled steel sheet provided by the invention, is comprised of following chemical composition: C:0.08～0.13% by weight percentage; Si:0.05～0.5%; Mn:1.2～2.0%; P≤0.010%; S≤0.005%; Cr:0.6～1.5%; Ti:0.08～0.20%, Nb:0.02～0.08%, V:0.04～0.2%, chooses any one kind of them in Nb, V, Ti or multiple; Alt:0.02 ~ 0.1%; N≤0.006%; O≤0.004%; All the other are iron Fe and inevitable impurity.
Preferably, above-mentioned cold-rolled steel sheet is comprised of following chemical composition by weight percentage: C:0.09～0.11%; Si:0.15～0.3%; Mn:1.5～1.8%; P≤0.010%; S≤0.005%; Cr:0.8～1.2%; Ti:0.08～0.16%, Nb:0.04～0.06%, V:0.04～0.1%, chooses any one kind of them in Nb, V, Ti or multiple; Alt:0.03 ~ 0.06%; N≤0.006%; O≤0.004%; All the other are iron Fe and inevitable impurity.
The cold rolling High Strength Steel Plate of 980MPa rank provided by the invention, on the basis of carbon manganese structure iron composition, by adding one or more in appropriate Nb, V, Ti, and Cr microalloy element, and the steel band after employing hot rolling Controlled Rolling And Controlled Cooling is as cold rolling feeds, carries out cold rolling and annealing.Consider the production feature of ordinary hot continuous mill, make full use of refined crystalline strengthening and precipitation strength mechanism, control the grain-size of As rolled steel band below 5 μ m, the size of the Carbonitride Precipitation phase of the alloying elements such as Nb, V, Ti is below 30nm; The strict content of controlling S and Si, in lower level, has produced tensile strength more than 980MPa simultaneously, and unit elongation, more than 8%, has the steel band of good processability, can meet the needs of automotive light weight technology manufacturing technology.
The effect of above-mentioned each chemical composition is made to concrete analysis below.
C: be main gap solid solution element in steel, can improve the intensity of steel.Adopt low-carbon (LC) composition design method can not only guarantee plasticity and the toughness that micro-Yu Gangyou of closing is good, and can effectively improve the hot and cold deformability of steel.Meanwhile, along with the reduction of carbon content and the reduction of carbon equivalent, can make micro-alloyed steel can keep good weldability.While being cooled to low temperature after rolling, can form tiny carbide (Nb, Ti) C with Ti and Nb, play important precipitation strength and use.Carbon content, higher than 0.13%, although can improve intensity, can cause cold forming capability and welding property greatly to reduce.In addition, load when cold rolling increases significantly, and rolling pass increases, and obtaining thickness of slab is the cold-rolled steel sheet difficulty increase below 0.2mm, and cost increases.The too low meeting of carbon content causes the increase of cost, and in addition, the precipitated phase of the carbide of formation is not enough, unfavorable to the intensity of cold rolled annealed steel plate.Therefore, in the present invention, from cold rolling angle, for guaranteeing intensity and cost, make C amount under be limited to 0.08%.
Si: can solid solution in ferrite and austenite, improve the intensity of steel.Improve quenching, normalizing and the annealing temperature of steel, improve temper resistance and the oxidation-resistance of steel.Si content is higher than more than 0.5% will damaging toughness and the plasticity of steel, deterioration weldability; In addition, increase the thickness of steel scale on surface, affect the surface quality of steel plate, be unfavorable for the surface quality of cold-rolled products.Experiment showed, that preferred Si content is 0.15～0.3%.
Mn: can reduce austenite to the transformation temperature of ferritic transformation, and austenite has refining effect to the reduction of the transformation temperature of ferritic transformation for the ferrite grain size of As rolled or normalizing state steel, therefore, Mn is widely used as the main alloy element in high strength microalloy steel for a long time.Mn is too high will there is martensitic transformation, control badly will produce large-sized M/A tissue, increase crack sensitivity, and too low solid solution strengthening effect is not obvious, thereby affects strength property.Therefore the preferred span of Mn is determined 1.5～1.8%.
P: can improve armor plate strength; Yet P too high levels reduces cold-rolling property.In addition, the p of high level tendency of segregation in steel is strong, causes the embrittlement of weld part.Therefore, in the present invention, preferably span is determined below 0.01%.
S: easily form sulfide inclusion in steel, make surface of cold-rolled steel plate form the defects such as cavity.Can make erosion resistance reduce simultaneously, therefore wish to reduce its content as far as possible.Preferably reduce as mentioned above as far as possible, but from the angle of steel-making ability and cost, be preferably approximately below 0.005%.
Cr: chromium can improve intensity and hardness and the wear resistance of steel.Chromium adds the high-temperature oxidation resistance (non-scale) that can significantly improve steel in steel, significantly improves the hardening capacity of steel, improves the anti-temper resistance of steel.On the other hand, chromium also can promote the temper brittleness tendency of steel.Cr content is lower than 0.3% time, and anti-wear-resisting effect is poor.In order to improve intensity, suitably bring up to 1.2%, do not affect use properties and the effect of this steel.Therefore, preferably the useful range of Cr is 0.8～1.2%.
Nb: can improve the non-recrystallization district temperature of steel, ensure the effect of controlled rolling, make grain refining after Steel Rolling, the NbC precipitation particles rolling later stage that Nb separates out simultaneously has precipitation strength effect.Preferable range is 0.04% ~ 0.06%.
V: the easiest solid solution in micro alloying element, continuous casting is not prone to transverse crack.In addition, because the Solid solution precipitation temperature of micro alloying element V is lower, therefore, the Heating temperature needing is lower, therefore, can produce under close condition and produce at C-Mn steel.Containing V steel, can produce by recrystallize controlled rolling, its rolling temperature is higher, needn't improve copper coin intensity by reducing finishing temperature, therefore, does not need to increase considerably mill load, and the relative finishing temperature of its mechanical property is insensitive.The precipitation strength successful of later stage VC.Preferred V is 0.04～0.1%.
Ti: be precipitation strength element important in the present invention, separate out TiN during high temperature, effectively stop AUSTENITE GRAIN COARSENING.While batching, from Precipitation, be nanometer TIC or (Nb, Ti) C particle, effectively pin dislocation, thus improve yield strength.Especially for cold-rolled products, be the main second phase particles of proof strength after annealing.Select its span of control 0.08% ~ 0.16%.
Al: add as reductor, can improve the purity of steel, the effect of crystal grain thinning again simultaneously.When Al content is less than 0.01%, deoxidation effect is little, and inclusion is residual and plasticity is reduced.But when Al amount surpasses 0.1%, the surperficial purity of steel plate declines, preferably Alt:0.03 ~ 0.06%.
N:N is solid solution in steel plate, if content surpasses 0.01%, makes the remarkable hardening of steel plate, therefore its content is made as below 0.010%.In addition, the not special restriction of the lower limit of N amount, but be preferably approximately below 0.006% from steel-making ability and cost consideration.
O: easily form inclusion in steel, but consider smelting cost, be preferably approximately below 0.004%.
Cold rolling High Strength Steel Plate provided by the invention is according to different thickness specifications, and yield strength Rel can reach 980～1100MPa, and tensile strength Rm can reach 1000～1200MPa, and unit elongation δ can reach 6～12%.Steel welding property and processability are good, and finished product thickness can be 0.8-1.5mm.
The concrete technical scheme of above-mentioned cold-rolled steel sheet manufacture method provided by the invention is as follows: comprise smelting, refining, continuous casting, hot rolling, cold rolling, annealing operation, wherein, in described annealing operation, steel after adopting bell type annealing furnace to hot rolling carry out anneal, annealing temperature is 600 ~ 720 ℃, and soaking time is 10-16h.Annealing operation is to guarantee the important operation of the finished product performance.Can realize yield strength and reach 980MPa, depend primarily on annealing time and the annealing temperature of this operation.Owing to adopting bell type annealing furnace, can not realize high temperature annealing, can only realize by the mode of refined crystalline strengthening and precipitation strength final high strength.Therefore, annealing temperature is chosen between 600 ~ 720 ℃, and soaking time is controlled within the scope of 10-16h.Guaranteed the precipitating reinforcing effect of the precipitated phase particles such as TIC; Simultaneously recrystal grain is partly grown up and can too do not grown up, and guarantees that grain-size exists partial dislocation substructure, refined crystalline strengthening successful when as follows at 6 μ m.
Preferably annealing temperature is 650 ~ 680 ℃, and soaking time is 12-14h, and the slow cooling time subsequently control as 20-30h, more preferably, the slow cooling time is 24-26h.The described slow cooling time can also be 22h, 25h, 28h etc.
Described annealing temperature can be the interval or concrete numerical value of any numerical value within the scope of said temperature, such as: 600-610 ℃, 700-720 ℃, 680-690 ℃, 640-650 ℃, 620 ℃, 630 ℃, 670 ℃ etc.Described soaking time can be also any numerical value interval within the scope of said temperature or concrete numerical value, such as: 10h, 12h, 13h, 15h etc.
In described cold rolling process, the raw material that hot rolling is complete carries out pickling, removes scale on surface and carries out rewinding.Cold rollingly on reversable mill, carry out, the passage of selecting 8-12 not wait according to different thickness is rolled, also can select a rolling process or two rolling processes to complete, preferably cold rolling draft is 65%-85%, can be exemplarily 67%, 70%, 76%, 78%, 82%, 70-80% more preferably, such as 72%, 74%, 78%.
In described hot-rolled process, preferably, the continuously cast bloom that just contains above-mentioned Chemical Composition is placed in process furnace, Heating temperature is 1200～1300 ℃, exemplary can for 1210～1225 ℃, 1235～1250 ℃, 1260～1270 ℃, 1280～1295 ℃, concrete can be 1205 ℃, 1250 ℃, 1290 ℃; Be 90 ~ 180 minutes heat-up time, and that exemplary can be 95min, 108min, 120min, 136min, 150min, 160min; Hot rolling finishing temperature is 850 ℃ ~ 900 ℃, and exemplary can be 860 ℃, 875 ℃, 895 ℃; Coiling temperature is 550 ℃ ~ 650 ℃, and exemplary can be 560 ℃, 570 ℃, 620 ℃, 640 ℃.More preferably, thickness of strand is 170-175mm, rough rolling process carries out 3～5 passage rollings, middle sotck thinkness is 28～40mm, hot rolling finishing temperature is 850 ℃ ~ 900 ℃, then carries out laminar flow cooling, and speed of cooling is 5～20 ℃/S, concrete can be 6 ℃/S, 8 ℃/S, 10 ℃/S, 15 ℃/S, 18 ℃/S, and hot-rolled finished product thickness is less than 4mm.
By above-mentioned technique, the present invention has realized the tensile strength of cold-rolled products more than 980MPa and high unit elongation.
Enumerate several embodiment below.In embodiment, the testing method of the mechanical property of product adopts GB-T2975-1998 < < steel mechanics performance and technological property test sampling regulation > > standard.
The chemical composition scope of the steel plate of setting according to the present invention, following embodiment is by following concrete technology flow process: with chemical composition C, Si, Mn, S, P and Fe are raw material, carry out converter smelting, refining process carries out Nb to molten steel, V, Ti, the Alloying Treatment such as Cr, continuous casting, strand direct heating or soaking, hot continuous rolling, roll rear laminar flow water cooling, batch, the flow process such as pickling, cold rolling, annealing, finishing is prepared from.
EXAMPLE l
The chemical composition of the cold-rolled steel sheet of the present embodiment design is by weight percentage: C:0.09%, Si:0.25%, Mn:1.9%, Nb:0.035%; Ti:0.15%; Cr:0.8%; P:0.008%; S:0.001%; N:0.0051%; O:0.0038%; Alt:0.036%; All the other are iron Fe and inevitable impurity.According to mentioned component design, raw material is smelted in 120 tons of converters, and in refining process, carry out Nb, Ti, Cr Alloying Treatment, then continuous casting becomes the continuously cast bloom of 175mm * 1210mm * 11800mm, continuously cast bloom is heated to 1250 ℃, 160 minutes heat-up times, rolling on hot continuous mill, it is 1150 ℃ that roughing start rolling temperature is controlled, it is 1050 ℃ that roughing finishing temperature is controlled, roughing 5 passages, intermediate blank is thick is 30mm, it is 1020 ℃ that finish rolling start rolling temperature is controlled, it is 880 ℃ that finish rolling finishing temperature is controlled, finish rolling 6 passages, average every time the draught of finish rolling is controlled at 25%, between finishing mill, adopt water-cooled, blank after the rolling is carried out to laminar flow cooling, speed of cooling is 15 ℃/S, and coiling temperature is 590 ℃.Cold rolling after the steel band pickling that is 3.8mm by hot outgoing gauge, rolling pass is 8 roads, and cold rolling draft is 75%, and cold rolling rear product thickness is 1.2mm.Then in bell-type annealing furnace annealing, annealing temperature is controlled at 675 ℃, soaking time 12h, and the slow cooling time is 24h.
Its mechanical property the results are shown in Table 1.
The mechanical property result of the cold-rolled steel sheet of table 1 embodiment 1
Embodiment 2
The chemical composition of the cold-rolled steel sheet of the present embodiment design is by weight percentage: C:0.1%, Si:0.28%, Mn:1.8%, Nb:0.06%; Ti:0.14%; Cr:1.0%; P:0.009%; S:0.003%; N:0.0045%; O:0.0036%; Alt:0.032%; All the other are iron Fe and inevitable impurity.
According to mentioned component design, raw material is smelted in 120 tons of converters, and in refining process, carry out Nb, Ti, Cr Alloying Treatment, then continuous casting becomes the continuously cast bloom of 175mm * 1230mm * 11800mm, continuously cast bloom is heated to 1260 ℃, 172 minutes heat-up times, it is 1190 ℃ that roughing start rolling temperature is controlled, it is 1040 ℃ that roughing finishing temperature is controlled, roughing 5 passages, the thick 35mm of intermediate blank, after this intermediate blank is carried out to finish rolling, it is 1000 ℃ that finish rolling start rolling temperature is controlled, it is 850 ℃ that finish rolling finishing temperature is controlled, finish rolling 5 passages, average every time the draught of finish rolling is controlled at 24%, between finishing mill, adopt water-cooled, blank after the rolling is carried out to laminar flow cooling, speed of cooling is 20 ℃/S, and coiling temperature is 550 ℃, cold rolling after the steel band pickling that is 3.7mm by hot outgoing gauge, rolling pass is 9 roads, and cold rolling draft is 80%, and cold rolling rear product thickness is 1.0mm.Then in bell-type annealing furnace annealing, annealing temperature is controlled at 645 ℃, soaking time 13h, and the slow cooling time is 25h.
Its mechanical properties test the results are shown in Table 2.
The mechanical property result of the cold-rolled steel sheet of table 2 embodiment 2
Embodiment 3
The chemical composition of the cold-rolled steel sheet of the present embodiment design is by weight percentage: C:0.09%, Si:0.18%, Mn:1.85%, Nb:0.055%; Ti:0.16%; Cr:0.9%; P:0.01%; S:0.004%; N:0.0041%; O:0.0033%; Alt:0.030%; All the other are iron Fe and inevitable impurity.
According to mentioned component design, raw material is smelted in 120 tons of converters, and in refining process, carry out Nb, Ti, Cr Alloying Treatment, then continuous casting becomes the continuously cast bloom of 175mm * 1230mm * 11800mm, continuously cast bloom is heated to 1270 ℃, 165 minutes heat-up times, it is 1180 ℃ that roughing start rolling temperature is controlled, it is 1040 ℃ that roughing finishing temperature is controlled, roughing 5 passages, the thick 33mm of intermediate blank, after this intermediate blank is carried out to finish rolling, it is 1000 ℃ that finish rolling start rolling temperature is controlled, it is 850 ℃ that finish rolling finishing temperature is controlled, finish rolling 5 passages, average every time the draught of finish rolling is controlled at 23%, between finishing mill, adopt water-cooled, blank after the rolling is carried out to laminar flow cooling, speed of cooling is 22 ℃/S, and coiling temperature is 570 ℃, by cold rolling after the steel band pickling of the 3.7mm after hot rolling, rolling pass is 9 roads, and cold rolling draft is 82%, and cold rolling rear product thickness is 1.1mm.In bell-type annealing furnace annealing, annealing temperature is controlled at 700 ℃, soaking time 14.5h, and the slow cooling time is 26h.
Product mechanical properties test the results are shown in Table 3.
The mechanical property result of the cold-rolled steel sheet of table 3 embodiment 3
Embodiment 4
The chemical composition of the cold-rolled steel sheet of the present embodiment design is by weight percentage: C:0.09%, Si:0.20%, Mn:1.82%, Nb:0.040%; V:0.045%; Ti:0.12%; Cr:0.92%; P:0.01%; S:0.004%; N:0.0041%; O:0.0033%; Alt:0.030%; All the other are iron Fe and inevitable impurity.
According to mentioned component design, raw material is smelted in 120 tons of converters, and in refining process, carry out Nb, Ti, Cr, V alloyization is processed, then continuous casting becomes the continuously cast bloom of 175mm * 1230mm * 11800mm, continuously cast bloom is heated to 1270 ℃, 166 minutes heat-up times, it is 1180 ℃ that roughing start rolling temperature is controlled, it is 1045 ℃ that roughing finishing temperature is controlled, roughing 5 passages, the thick 31mm of intermediate blank, after this intermediate blank is carried out to finish rolling, it is 1050 ℃ that finish rolling start rolling temperature is controlled, it is 855 ℃ that finish rolling finishing temperature is controlled, finish rolling 5 passages, average every time the draught of finish rolling is controlled at 23%, between finishing mill, adopt water-cooled, blank after the rolling is carried out to laminar flow cooling, speed of cooling is 22 ℃/S, and coiling temperature is 570 ℃, by cold rolling after the steel band pickling of the 3.7mm after hot rolling, rolling pass Wei10 road, cold rolling draft is 85%, cold rolling rear product thickness is 1.0mm.In bell-type annealing furnace annealing, annealing temperature is controlled at 700 ℃, soaking time 13.5h, and the slow cooling time is 26h.
Product mechanical properties test the results are shown in Table 4.
The mechanical property result of the cold-rolled steel sheet of table 4 embodiment 4
Embodiment 5
The chemical composition of the cold-rolled steel sheet of the present embodiment design is by weight percentage: C:0.08%, Si:0.18%, Mn:1.82%, V:0.045%; Ti:0.15%; Cr:1.0%; P:0.008%; S:0.003%; N:0.0046%; O:0.0035%; Alt:0.030%; All the other are iron Fe and inevitable impurity.
According to mentioned component design, raw material is smelted in 120 tons of converters, and in refining process, carry out V, Ti, Cr Alloying Treatment, then continuous casting becomes the continuously cast bloom of 175mm * 1230mm * 11800mm, continuously cast bloom is heated to 1260 ℃, 162 minutes heat-up times, it is 1170 ℃ that roughing start rolling temperature is controlled, it is 1035 ℃ that roughing finishing temperature is controlled, roughing 5 passages, the thick 32mm of intermediate blank, after this intermediate blank is carried out to finish rolling, it is 1050 ℃ that finish rolling start rolling temperature is controlled, it is 855 ℃ that finish rolling finishing temperature is controlled, finish rolling 5 passages, average every time the draught of finish rolling is controlled at 23%, between finishing mill, adopt water-cooled, blank after the rolling is carried out to laminar flow cooling, speed of cooling is 22 ℃/S, and coiling temperature is 570 ℃, by cold rolling after the steel band pickling of the 3.7mm after hot rolling, rolling pass Wei11 road, cold rolling draft is 85%, cold rolling rear product thickness is 0.85mm.In bell-type annealing furnace annealing, annealing temperature is controlled at 700 ℃, soaking time 14h, and the slow cooling time is 26h.
Product mechanical properties test the results are shown in Table 5.
The mechanical property result of the cold-rolled steel sheet of table 5 embodiment 5
Test-results shows that the present invention carries the high-intensity while, possesses good welding property and cold forming capability, meets the requirement of automobile structural steel user's use.Select representative microstructure as shown in Figure 1.Fig. 1 is the annealing microstructure of the high tensile steel plate of embodiment 5 preparations, as can be seen from the figure the fibrous texture of part recrystallized structure and cold rolled annealed rear remnants coexists, recrystallized structure guarantees that 980Mpa level steel possesses certain plasticity, and fibrous tissue and substructure have guaranteed the high strength of steel.
Claims (6)
1. a manufacture method for yield strength 980MPa level cold-rolled steel sheet, comprises smelting, refining, continuous casting, hot rolling, cold rolling, annealing operation, it is characterized in that,
In described hot-rolled process, the continuously cast bloom that the operation by described smelting, described refining and described continuous casting is obtained is placed in process furnace, and Heating temperature is 1200～1300 ℃, and described thickness of strand is 170-175mm; Roughing rolling pass in described hot-rolled process is 3-5 passage, and the middle sotck thinkness after described roughing is 28-40mm, and hot rolling finishing temperature is 850-900 ℃, then carry out laminar flow cooling, speed of cooling is 5-20 ℃/s, and hot-rolled finished product thickness is less than 4mm, and coiling temperature is 550 ℃～650 ℃;
In described annealing operation, adopt bell type annealing furnace to carry out anneal to the steel after cold rolling, annealing temperature is 600～720 ℃, soaking time is 10-16h;
After described annealing operation, carry out slow cooling, the slow cooling time is 20-30h;
This yield strength 980MPa level cold-rolled steel sheet is comprised of following chemical composition by weight percentage: C:0.08～0.13%; Si:0.05～0.5%; Mn:1.2～2.0%; P≤0.010%; S≤0.005%; Cr:0.6～1.5%; Ti:0.08～0.20%, Nb:0.02～0.08%, V:0.04～0.2%, Nb, V and Ti choose any one kind of them or are multiple; Alt:0.02～0.1%; N≤0.006%; O≤0.004%; All the other are iron Fe and inevitable impurity.
2. the manufacture method of yield strength 980MPa level cold-rolled steel sheet according to claim 1, is characterized in that,
In described cold rolling process, the raw material through described hot-rolled process is carried out to pickling, after removal scale on surface, carry out rewinding, then on milling train, be rolled, cold rolling draft is 65%-85%.
3. the manufacture method of yield strength 980MPa level cold-rolled steel sheet according to claim 2, is characterized in that, described cold rolling draft is 70-80%, and described milling train is reversable mill.
4. the manufacture method of yield strength 980MPa level cold-rolled steel sheet according to claim 1, is characterized in that,
The described slow cooling time is 24-26h.
5. the manufacture method of yield strength 980MPa level cold-rolled steel sheet according to claim 1, is characterized in that,
Described annealing temperature is between 650～680 ℃, and soaking time is 12-14h.
6. the manufacture method of yield strength 980MPa level cold-rolled steel sheet according to claim 2, is characterized in that, described milling train is reversable mill, and described cold rolling draft is to complete in 8～12 passages.
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| AU2013205082B2 (en) * | 2013-04-13 | 2017-04-27 | Infrabuild Construction Solutions Pty Ltd | Steel product and method of producing the product |
| CN104294145A (en) * | 2014-10-20 | 2015-01-21 | 山东钢铁股份有限公司 | Bell-type annealing treatment-based cold rolled steel with tensile strength of 600MPa, and preparation method thereof |
| CN105039856A (en) * | 2015-09-11 | 2015-11-11 | 首钢总公司 | High-strength cold-formed automobile axle housing steel and production method thereof |
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| CN108914000B (en) * | 2018-07-24 | 2020-10-02 | 唐山钢铁集团有限责任公司 | Cold-rolled dual-phase steel with 780 MPa-grade tensile strength and production method thereof |
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| CN112593154A (en) * | 2020-11-30 | 2021-04-02 | 攀钢集团攀枝花钢铁研究院有限公司 | 980 MPa-grade cold-rolled dual-phase steel with yield strength exceeding 700MPa and production method thereof |
| CN112662943A (en) * | 2020-11-30 | 2021-04-16 | 山东钢铁股份有限公司 | Low-alloy high-strength hot-rolled round steel Q460D and preparation method thereof |
| CN113136528A (en) * | 2021-04-23 | 2021-07-20 | 唐山全丰薄板有限公司 | 1500 MPa-grade ultrahigh-strength cold-rolled steel plate for automobiles and manufacturing method thereof |
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