CN101871078B - Super-high strength cold rolled steel and manufacturing method thereof - Google Patents
Super-high strength cold rolled steel and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses super-high strength cold rolled steel or steel plate, which comprises the following chemical components in percent by weight: 0.08 to 0.18 percent of C, 0.1 to 0.6 percent of Si, 1.4 to 2.4 percent of Mn, less than or equal to 0.02 percent of P, less than or equal to 0.005 percent of S, 0.01 to 0.05 percent of A1, less than or equal to 0.006 percent of N, 0.2 to 0.77 percent of B/N and the balance of Fe and inevitable impurities. A manufacturing method for the super-high strength cold rolled steel comprises the following steps: performing hot rolling, wherein the finishing temperature is between 830 and 930 DEG C and the coiling temperature is between 550 and 650 DEG C; performing cold rolling, wherein the rolling reduction is 40 to 70 percent; performing continuous annealing, namely holding the temperature between 780 and 880 DEG C, cooling the steel to be between 700 and 750 DEG C with air at a rate of between 10 and 30 DEG C/s, cooling the steel to be between 550 and 640 DEG C by air blast at the cooling rate of between 60 and 200 DEG C/s, cooling the steel to be below 100 DEG C at the cooling rate greater than 500 DEG C/s and heating the steel to be between 150 and 250 DEG C to perform tempering for 60 to 300s; washing the steel with weak acid; and levelling the steel by 0 to 0.6 percent. Thus the obtained super-high strength band steel or steel plate with high processability can be applied to structures or enhanced parts for automobile manufacturing.
Description
Technical field
The present invention relates to super-high strength cold rolled steel, particularly have the superhigh intensity cold rolling band steel or the steel plate of high working property, and their method of manufacture.
Background technology
In automotive industry, when producing car, use cold-rolled steel sheet in a large number.From the needs of loss of weight, require steel plate is carried out attenuate.Simultaneously, to safe requirement, the requirement of body stiffness is also improved constantly.Therefore the steel plate of cold-rolled high-strength has application promise in clinical practice aspect automobile making.Cold rolling ultrahigh-strength steel is particularly suitable for the manufacturing of car safety spare, like door bumper, collision bumper reinforcement etc.At present, ultrahigh-strength steel all adopts the means of phase transformation strengthening, when continuous annealing, adopts cooling faster, to obtain the martensite of inequality, is called dual phase steel and martensitic steel respectively.
Publication number is that the U.S. Patent application of US20030005986A discloses a kind of super-high strength cold rolled steel and method of manufacture thereof.Its chemical ingredients is: C 0.01～0.07%, the Mn of Si≤0.30%, 1.6～2.5%, Cr or Mo, and P≤0.10%, S≤0.01%, N≤0.005%, Al 0.01～0.10%, and other is that Fe forms with inevitable impurity.The disclosed technology of the document is batched through in the above temperature hot rolling of Ar3, and is cold rolling; Annealing more than Ac3 (complete austenitizing temperature); Be cooled between 68～750 ℃ with 20 ℃/s cooling rate, then with after being cooled to 50 ℃ greater than 500 ℃/s, in tempering between 100～250 ℃ more than 3 minutes; After smooth, the hole expansibility that can obtain tensile strength 880～1170MPa is at the ultrahigh-strength steel more than 75%.
Publication number is that the european patent application of EP1512762A1 discloses a kind of ultrahigh-strength steel and method of manufacture thereof.Its chemical ingredients is: C 0.07～0.15%, and Si 0.7～2%, and Mn 1.8～3%, P≤0.02%; S≤0.01% ,≤0.005%N, Al 0.01～0.10%, B:0.0003～0.003%; Ti:0.003～0.03%, Mo:0.1～1%, other is that Fe forms with inevitable impurity.The disclosed technology of the document is batched through in the above temperature hot rolling of Ar3, and is cold rolling; 800～870 ℃ of annealing, slow cooling to 650～750 ℃ are again from 650～750 ℃; After being cooled to 100 ℃ with the above cooling rate of 500 ℃/s; 325～425 ℃ of tempering 5～20 minutes, smooth after, can obtain the ultrahigh-strength steel that tensile strength is 980MPa.
Publication number is the method for manufacture that the Japanese patent application of JP6-271942A discloses the super high tensile cold-rolled steel plate of a kind of tensile strength more than 100kgf.Its chemical ingredients is: C 0.1～0.3%, Si≤1%, and Mn 1～3.0%; P≤0.02%, S≤0.01%, Al 0.01～0.05%; N≤0.005%, B0.0003～0.003%, and contain Ti 0.005～0.05%; Nb 0.005～0.05%, one or more among the V 0.01～0.1%.The disclosed technology of the document is through hot rolling, cold rolling, after the above heat tracing of Ac3 is handled, is cooled to 450～650 ℃ with the cooling rate of 10～40 ℃/s, is cooled to below 350 ℃ with the above cooling rate of 100 ℃/s again, is being incubated 30～600s below 350 ℃ then.
Publication number is the method for manufacture that the Japanese patent application of JP2004308002A discloses the ultrahigh-strength steel of a kind of 1180MPa; Its chemical ingredients is: C:0.06～0.6%; Si+Al:0.50～3%, Mn:0.5～3.0%, P≤0.15%; S≤0.02%, other is that Fe forms with inevitable impurity.The disclosed technology of the document adopts between A3～1100 ℃ and is incubated 10s, and the speed of cooling above with 30 ℃/s is cooled to below the Ms point.This technological steel has good unit elongation and anti-hydrogen embrittlement postpones the rimose characteristics.
Publication number is the method for manufacture that the Japanese patent application of JP2004231992A discloses a kind of ultrahigh-strength steel, and its chemical ingredients is: C:0.05～0.3%, Si:0.01-3%, Mn:0.01～4.0%; P:0.0001-0.20%, S≤0.02%, Al:0.01～3.0%; N:0.0001～0.01%, Ni:0.001～5.5%, Cu:0.001～3.0%; Cr:0.001～5.0%, Mo:0.005-5%, other is that Fe forms with inevitable impurity.This process using hot rolling and cold rolling after, 600～950 ℃ of recrystallization annealings, smooth then.This technological steel has the good resistance hydrogen embrittlement and postpones the rimose characteristics.
Publication number is the method for manufacture that the Japanese patent application of JP2004-263270A discloses the super high tensile cold-rolled steel plate of a kind of tensile strength more than 980MPa, and its chemical ingredients is C:0.12～0.18%, Si:0.2～0.8%; Mn:2.2～3.0%, P≤0.018%, S≤0.003%; Al≤0.05%, N≤0.005%, Ti:0.001～0.03%; Also has Nb≤0.001～0.05% in addition; B 0.0001～0.005%, and Mn satisfies-100 [C]+15≤Mn≤-100 [C]+20 simultaneously, and other is that Fe forms with inevitable impurity.Steel is through hot rolling, cold rolling, after heat tracing is handled, is cooled to be incubated between (Ms-100)～(Ms+50) with the cooling rate of 10～100 ℃/s and handles 60～240s.
The method of manufacture of the ultrahigh-strength steel that US20030005986A, JP2004308002A, JP2004231992A, JP2004-263270A and the disclosed technology of EP 1512762A1 relate to; When carrying out continuous annealing, adopt the types of cooling such as water-cooled, atomized water spray and gas cooling to obtain martensitic stucture respectively.Water-cooled rate of cooling is higher than 500 ℃/s, and the water smoke speed of cooling is at 100～200 ℃/s, and jet gas cooling speed then has only tens degree per seconds.Under the high rate of cooling (like shrend), obtain same intensity and only need add less alloying element, but technical difficulty is big; Cool off fast under the high temperature; The difficult control of plate shape is prone to cause the production problem that can't lead to plate (promptly can't unimpededly passing through), and the plate shape of product is also poor; Internal stress is big, influences following process (like shearing, itemize, shaping etc.).Low speed of cooling then need add more alloying element content, causes cost to raise.Hardness owing to the non-as-quenched condition of steel plate raises greatly simultaneously, so the production difficulty is big, and product cost is high, and weldableness is also relatively poor in addition.
More than relate to ultrahigh-strength steel plates the technology otherwise through high speed of cooling (like shrend), with the minimizing alloying element addition; Just adopt conventional cooling rate, add more alloying element in the steel.The former, high for production unit (continuous annealing unit) technical requirements, the relatively poor problem of plate shape appears in the steel plate of production easily, is prone to residual big internal stress in the steel plate; Therefore the latter makes cost improve owing to need add noble elements such as Cr, Mo, has wasted resource, and weldableness is descended.
In addition, ultrahigh-strength steel plates generally is used for structure and strengthens the less part of equidimension, so the coil of strip that steel mill produces also needs following process such as slitting striping usually.Because the plate shape of ultrahigh-strength steel is poor, hardness is high, internal stress is big, warpage takes place when rip cutting or blanking easily, the too fast or damage of tool wear, this can cause the failure of following process or difficulty of processing is increased.
Summary of the invention
An object of the present invention is to provide a kind of super-high strength cold rolled steel, particularly be with steel or steel plate with high working property.
The present invention designs with improved technology through reasonable component design cooperation; Make the ultrahigh-strength steel of tensile strength more than 980MPa, and in manufacturing processed, can take into account good plate shape, simultaneously; Guarantee rate of cooling faster again, to play the purpose of practicing thrift alloying element.
" high working property " among the present invention is meant that superstrength band steel or steel plate are easy to cut edge or itemize, and be lower to the requirement of cutter; Steel-plate shape is better, and internal stress is little, is difficult for warpage behind the itemize.
For realizing the object of the invention, the chemical ingredients of low-carbon (LC) superhigh intensity cold rolling band steel of the present invention or steel plate is C:0.08～0.18wt%, Si:0.1～0.6wt%; Mn:1.4～2.4wt%, P≤0.02wt%, S≤0.005wt%; Al:0.01～0.05%, N≤0.006wt%, Cr:0.1～0.4%; B/N:0.2～0.77, other is Fe and inevitable impurity.Its microtexture mainly is made up of martensite, also has a certain amount of ferritic, does not get rid of the possibility that has a small amount of bainite.
Further, be the weldableness that makes the present invention realize and further improve ultrahigh-strength steel of the present invention more easily, preferred C:0.08～0.16wt%; Si:0.1～0.4wt%, Mn:1.6～2.2wt%, P≤0.01wt%; S≤0.003wt%, Al:0.02～0.04%, N≤0.005wt%; Cr:0.1～0.3%, B/N:0.3～0.7.
In order further to improve the cutting ability of ultrahigh-strength steel of the present invention; Help being with steel to be cut into steel plate; And the slitting striping of steel plate processing; On above-mentioned steel chemical composition basis, also add among Se and the Bi one or both, wherein the addition of Se is 0.01～0.03%, and the addition of Bi is 0.02～0.04%.
The present invention selects chemical ingredients and scope according to following principle:
C plays the effect that improves martensite hardness in dual phase steel, if carbon content is low excessively, martensite hardness is not enough.The C too high levels then is unfavorable for weldableness.Among the present invention, designed the carbon content that belongs to the low-carbon (LC) category, helped welding, but the addition of carbon can satisfy the requirement that under specific processing condition, obtains superstrength again.Therefore the content of carbon is 0.08～0.18% in the ultrahigh-strength steel of the present invention, is preferably 0.08～0.16%.
Si has the carbide of inhibition and separates out in steel, improve the effect of martensite temper resistance, helps in the drawing process, keeps martensitic hardness.But the too high meeting of Si causes plate surface quality to descend.Therefore silicone content is 0.1～0.6wt% in the ultrahigh-strength steel of the present invention, is preferably 0.1～0.4wt%.
Mn has remarkably influenced for hardening capacity, can promote martensitic formation, helps improving the intensity of steel.Mn content is controlled at 1.4～2.4wt% in the ultrahigh-strength steel of the present invention, and preferred 1.6～2.2%.
P, S are impurity element in steel.Control lower P, S and help improving performance.In ultrahigh-strength steel of the present invention, control P≤0.02wt%, S≤0.005wt% preferably controls P≤0.01wt%, S≤0.003wt%.
Al plays desoxydatoin and crystal grain thinning in steel.Control Al is 0.01～0.05% in ultrahigh-strength steel of the present invention, is preferably Al:0.02～0.04%.
N is the element that exists in the smelting process, need it be controlled at certain scope.In ultrahigh-strength steel of the present invention, control N≤0.006wt%, be preferably N≤0.005wt%.
The interpolation of B is lower than the B/N stoichiometric ratio, and the nitrogen that contains in B and the steel combines to form BN.Owing to exist with compound form, B does not improve the hardening capacity of steel.The BN that forms helps as the trap that absorbs hydrogen, thereby improves the anti-delay cracking property of steel.In ultrahigh-strength steel of the present invention, control B/N:0.2～0.77, be preferably B/N:0.3～0.7.
Se and Bi play the function of improving cutting characteristic in steel, can make superhard ultrahigh-strength steel when slitting striping, and the tangent plane burr reduces, and the itemize quality improves, to the requirement of cutter with to the corresponding reduction of the wearing and tearing of cutter.In order to improve cutting characteristic, can select among Se and the Bi one or both in the ultrahigh-strength steel of the present invention for use, when adding Se and/or Bi, the addition of Se is controlled at 0.01～0.05%, and the addition of Bi is controlled at 0.02～0.05%.
Another object of the present invention provides a kind of method of manufacture of superhigh intensity cold rolling band steel.
Superhigh intensity cold rolling band steel of the present invention is accomplished through following technical process: smelting → casting → hot rolling → pickling → cold rolling → continuous annealing.
Wherein, smelting is adopted known in the art, and routine smelting mode used in cold rolled strip or steel plate is carried out; Add external refining like converter smelting or converter smelting; Preferred converter smelting adds external refining, but is not limited only to this, any smelting mode that also can adopt other to be fit to.
Casting is adopted known in the art, and used routine casting mode is carried out in producing cold rolled strip or steel plate, like continuous casting or die casting, and preferred continuous casting, but be not limited only to this, any casting mode that also can adopt other to be fit to.
Hot rolling is adopted known in the art; Used conventional hot rolling mode is carried out in producing cold rolled strip or steel plate; Comprise reheat, de-scaling, roughing, finish rolling, cooling and coiling process; Preferably the reheat temperature is 1180～1250 ℃, and finishing temperature is 830～930 ℃, and coiling temperature is 550～650 ℃.But be not limited only to this, any hot rolling mode that also can adopt other to be fit to as required.
Cold rolling employing is known in the art, and used conventional cold rolling mode is carried out in producing cold rolled strip or steel plate, as adopts 5 frame continuous rollings, and preferably cold rolling draft is 40～70%.But be not limited only to this, any cold rolling mode that also can adopt other to be fit to as required.
Pickling is adopted known in the art, and used conventional pickling mode is carried out in producing superhigh intensity cold rolling band steel or steel plate, washes like weak acid.But be not limited only to this, any pickling mode that also can adopt other to be fit to as required.
In the manufacturing of superhigh intensity cold rolling band steel of the present invention or steel plate, continuous annealing is the committed step that realizes the object of the invention.
780～880 ℃ of insulations are adopted in continuous annealing, and (soaking time adopts 40～300s); And be cooled to 700～750 ℃ so that the speed of 10～30 ℃/s is jet, be cooled to 550～640 ℃ with 60～200 ℃/s cooling rate high speed jet then, then shrend (cooling rate greater than 500 ℃/s) to below 100 ℃; At last; Behind ℃ tempering 60～300s of reheat to 150～250, wash through weak acid, smooth through 0～0.6% again.
Preferred continuous annealing process is: 780～850 ℃ of insulations; And be cooled to 700～750 ℃ so that 10～30 ℃/s speed is jet, be cooled to 580～620 ℃ with 100～200 ℃/s cooling rate high speed jet then, shrend then (cooling rate greater than 500 ℃/s) to below 100 ℃; At last; Behind ℃ tempering 60～200s of reheat to 180～220, wash through weak acid, smooth through 0～0.4% again.
Steel of the present invention under the situation of low-carbon (LC) and a small amount of alloying element of interpolation, just can obtain ultrahigh-strength steel 980MPa above tensile strength, the particularly tensile strength between 980～1400MPa through above-mentioned processing.Simultaneously, can obtain plate shape and less internal stress preferably, steel plate is when slitting striping, and distortion and warpage are little, and otch is neat, and burr is few, is easy to processing.In addition, be prone to the cutting element through adding, improve follow-up cutting plate performance, the edge quality that steel plate is cut off improves the cutter consumption when reducing rip cutting or crosscut simultaneously.
Select the reason of continuous annealing process condition to specifically describe as follows in the present invention:
For holding temperature: 780～880 ℃ of insulations.If temperature is lower than 780 ℃, then can not form enough austenites, if temperature above 880 ℃, then there is no need and wastes energy.
For first section cooling: be cooled to 700～750 ℃ so that 10～30 ℃/s speed is jet.This section cooling should guarantee that austenite low decomposes, and guarantees not variation of high temperature lower plate shape again.Cooling rate is crossed slow austenite and can be decomposed, and cooling rate is too fast unfavorable to plate shape.Temperature is low excessively to cause austenite too much to decompose, and temperature is too high, and then cooling rate is faster next stage, is unfavorable for plate shape.
For second section cooling:, be cooled to 550～640 ℃ with 60～200 ℃/s cooling rate high speed jet (like the nitrogen hydrogen compound gases of high hydrogen richness) from 700～750 ℃.This section austenite decomposition motivating force (austenitic transformation becomes ferritic and pearlitic motivating force) is bigger, therefore must strengthen cooling rate.Simultaneously, though temperature decreases, still be in higher temperature region after all, cooling rate can not be too fast, and is good to guarantee plate shape.Cooling rate is crossed low austenite and is prone to decompose, and cooling rate is too fast to be unfavorable for plate shape.If temperature is lower than 550 ℃, the part austenite can be transformed into non-martensite microstructure, is unfavorable for intensity.If temperature is higher than 640 ℃, when follow-up shrend, still cause plate shape bad easily.
For the 3rd section cooling: since 550～640 ℃ of shrends (cooling rate greater than 500 ℃/s) to below 100 ℃.Begin shrend from this lower temperature range, both helped improving plate shape, can obtain sufficient martensite again, with proof strength.Too high plate shape, the low excessively intensity that is unfavorable for of temperature of being unfavorable for of temperature.
Overaging and smooth: after being heated to 150～250 ℃ of tempering 60～300s, wash through weak acid, smooth through 0～0.6% again.Low overaging temperature is unfavorable for toughness, and too high overaging temperature is prone to cause the strength degradation of steel.
The present invention is through reasonable component design and be equipped with the technological process of improvement, under the content of moderate carbon and alloying element, and the acquisition super-high strength cold rolled steel.Both avoided high temperature to cool off difficult problems such as the plate shape of causing is bad fast,, rationally adjusted the different steps rate of cooling again according to the characteristics of steel cooling curve in different media and the phase transformation characteristics of steel.Be easy to variation plate shape, and austenite decomposes high-temperature zone slowly, adopted the lower common jet cooling of cooling rate; Be easier to variation plate shape, and the very fast middle temperature area that decomposes of austenite has adopted the cooling of the high faster hydrogen richness nitrogen of cooling rate hydrogen compound gases high speed jet; Be prone to assurance and need rapid quenching to become martensitic lesser temps interval plate shape, adopted fastest shrend cooling.So both guaranteed that steel can fully harden, steel plate has plate shape and less internal stress preferably simultaneously.In addition, also, help improving the performance of steel when following process, like slitting striping and blanking etc. through in steel, adding the element that Se, Bi etc. improve machinability.Both helped quality product, also reduced wearing and tearing cutter.
It is thus clear that composition of the present invention design cooperates the ultrahigh-strength steel with the technological design acquisition of improvement, not only can avoid high temperature to cool off difficult problems such as the plate shape of causing is bad fast, can also guarantee that steel can fully harden.Can guarantee that like this steel plate helps improving the characteristic of steel when following process preferably plate shape and less internal stress the time.Utilize method of manufacture of the present invention, taken into account the characteristics of the low alloyed element of shrend high-strength steel, plate shape difference that internal stress causes when also having improved the super-high strength steel following process and the high unmanageable problem of hardness.Also improve the shearing processibility of superstrength band steel of the present invention and steel plate through elements such as interpolation Se, Bi.
Improved the use properties of making feasibility, economy and the product of superstrength band steel and steel plate greatly according to composition design and processes of the present invention.From these several angles, all be superior to prior art.Ultrahigh-strength steel of the present invention can be applied to the structure of automobile making or the part of reinforcement, has certain application prospect.
Embodiment
Below the present invention is carried out bright comparatively specifically through embodiment.
It in the table 1 chemical ingredients of A1～A5 embodiment.
The chemical ingredients of table 1 invention steel, wt%
| Grade of steel | C | Si | Mn | Cr | P | S | Al | Se | Bi | N | B |
| A1 | 0.12 | 0.4 | 2.2 | 0.2 | 0.01 | 0.005 | 0.01 | 0.01 | 0.04 | 0.0035 | 0.002 |
| A2 | 0.08 | 0.3 | 2.4 | 0.25 | 0.01 | 0.003 | 0.04 | 0 | 0.05 | 0.004 | 0.0025 |
| A3 | 0.18 | 0.2 | 1.4 | 0.4 | 0.015 | 0.004 | 0.03 | 0.03 | 0.03 | 0.005 | 0.0025 |
| A4 | 0.14 | 0.6 | 1.8 | 0.3 | 0.011 | 0.003 | 0.02 | 0.04 | 0.02 | 0.0045 | 0.0015 |
| A5 | 0.16 | 0.5 | 2 | 0.1 | 0.012 | 0.005 | 0.05 | 0.05 | 0 | 0.006 | 0.002 |
Test steel A1-A5 with chemical ingredients shown in the table 1 makes through following process:
Obtain the steel billet of 40mm thickness after smelting, casting and the forging; This steel billet is heated to 1200 ℃, carries out hot rolling, finishing temperature is 830～930 ℃, obtains hot rolled strip, and simulates 550～650 ℃ and batch; After the pickling, the draft with 40～70% carries out cold rolling; Be heated to 780～880 ℃ and be incubated, and with the speed of 10～30 ℃/s with gas (nitrogen or contain 5% following H
2Nitrogen hydrogen mixeding gas) be cooled to 700～750 ℃; Speed with 60～200 ℃/s is cooled to 550～640 ℃ with high speed jet (like the nitrogen hydrogen compound gases or the helium hydrogen mixed gas of high hydrogen richness) then; Shrend then (cooling rate is greater than 500 ℃) is to below 100 ℃, and is last, behind ℃ tempering 60～300s of reheat to 150～250; Wash through weak acid, smooth through 0～0.6% again.
Steel of the present invention has adopted the syllogic process for cooling, and the process for cooling situation of each embodiment steel is as shown in table 2.
As stated through smelting, hot rolling, cold rolling, annealing and smooth after the steel of the present invention that obtains, its intensity is seen shown in the table 3.
Can find out from table 3, can produce the ultrahigh-strength steel of the high working property of tensile strength between 980-1400MPa according to composition design and processes process of the present invention.
According to the composition design and processes of steel of the present invention, steel plate that obtains or band steel, its microtexture mainly is made up of martensite, contains a certain amount of ferritic simultaneously, does not get rid of the possibility that contains a small amount of bainite in addition.Because hot stage has adopted gas cooling and high speed jet to cool off, therefore, in the ferritic the relative shrend of solid solution carbon lower, obtain the performance of low yield strength ratio easily.High-temperature zone cooling simultaneously is even, so plate shape is good, performance is also more even.Owing to added processing such as easy cutting elements such as Se, Bi, steel plate shearing easy to implement, itemize, reduce the loss of cutter in addition, improved shearing quality.
Steel of the present invention is when carrying out first section cooling, because temperature is higher, it is little that austenite decomposes motivating force, adopted the lower gas cooling of cooling rate.This is enough to guarantee that austenite does not decompose basically, and the gas cooling good uniformity helps plate shape simultaneously.And quick one-part form process for cooling such as employing shrend, the shrend in the high-temperature zone, cooling rate is too high, and inhomogeneous cooling is even, is prone to cause the rapid deterioration of steel-plate shape.When steel of the present invention carried out second section cooling, temperature reduced relatively, and austenite decomposition motivating force is bigger, needed to adopt higher cooling rate, and plate shape also is easier to guarantee simultaneously.So adopt the higher and jet cooling of uniform high hydrogen of cooling rate.This section as employing shrend, plate shape is still bad, if adopt slower gas cooling, though favourable to plate shape, austenite decomposes easily, so have to increase the alloying element addition.Steel of the present invention is when carrying out the 3rd section cooling, and temperature is lower, and austenite decomposition motivating force is very big, adopts shrend can make supercooled austenite be transformed into martensite entirely.Because temperature is lower, plate shape is easier to control simultaneously.At this moment, adopt one-part form shrend refrigerative steel plate in the high-temperature zone plate shape serious deterioration, still very poor through this stage cooling plate shape.And adopt gas-cooled technology, and itself is low with regard to cooling rate, and the low-temperature region cooling rate is lower in addition, is difficult to guarantee that austenite quenches into martensite, thus have to add a large amount of alloying elements, with assurance hardening capacity.
As showing 4-1, shown in the table 4-2, the steel of steel of the present invention and prior art is relatively more visible; The present invention cooperates the technological design with improvement through the reasonable component design, under the content of moderate carbon and alloying element, obtains ultrahigh-strength steel; Can avoid high temperature to cool off difficult problems such as the plate shape of causing is bad fast; According to the characteristics and the phase transformation characteristics of steel cooling curve in different media, rationally adjusted the different steps rate of cooling again, guaranteed that steel can fully harden.Can guarantee steel plate plate shape and less internal stress preferably like this.Simultaneously, added elements such as Se, Bi in the steel, helped improving the characteristic of steel when following process, like slitting striping or blanking etc.Both helped quality product, as improved otch burr etc., also reduced wearing and tearing cutter.Method of manufacture of the present invention has been taken into account the characteristics of the low alloyed element of shrend high-strength steel, simultaneously, can improve the relatively poor problem of plate shape that the high-temperature zone water-cooled causes greatly.Plate shape difference that internal stress causes when also having improved the super-high strength steel following process and the high unmanageable problem of hardness.Can improve the use properties of making feasibility, economy and product greatly,, all be superior to prior art from these several angles.
Ultrahigh-strength steel of the present invention can be used for the structure of automobile making or the part of reinforcement, has certain application prospect.
More than through embodiment the present invention has been carried out comparatively detailed explanation; But be not limited only to these embodiment; Not breaking away under the prerequisite of the present invention design, more diverse or improved other embodiment can also be arranged, and these variations and improve and all should belong to scope of the present invention.
Claims (12)
1. super-high strength cold rolled steel, its chemical ingredients by weight percentage is:
C:0.08～0.18wt%, Si:0.1～0.6wt%, Mn:1.4～2.4wt%, P≤0.02wt%; S≤0.005wt%, Al:0.01～0.05%, N≤0.006wt%; Cr:0.1～0.4%, B/N:0.2～0.77, other is Fe and inevitable impurity.
2. super-high strength cold rolled steel as claimed in claim 1 is characterized in that C:0.08～0.16wt%; Si:0.1～0.4wt%, Mn:1.6～2.2wt%, P≤0.01wt%; S≤0.003wt%, Al:0.02～0.04%, N≤0.005wt%; Cr:0.1～0.3%, B/N:0.3～0.7.
3. super-high strength cold rolled steel, its chemical ingredients by weight percentage is: C:0.08～0.18wt%, Si:0.1～0.6wt%, Mn:1.4～2.4wt%; P≤0.02wt%, S≤0.005wt%, Al:0.01～0.05%; N≤0.006wt%, Cr:0.1～0.4%, B/N:0.2～0.77; Also add among Se and the Bi one or both, Se:0.01～0.05% and/or Bi:0.02～0.05% wherein, other is Fe and inevitable impurity.
4. according to claim 1 or claim 2 super-high strength cold rolled steel is characterized in that, said steel is band steel or steel plate, and its tensile strength is more than the 980MPa.
5. super-high strength cold rolled steel as claimed in claim 3 is characterized in that, said steel is band steel or steel plate, and its tensile strength is more than the 980MPa.
6. super-high strength cold rolled steel as claimed in claim 4 is characterized in that, described steel plate tensile strength is 980～1400MPa.
7. super-high strength cold rolled steel as claimed in claim 5 is characterized in that, described steel plate tensile strength is 980～1400MPa.
8. like the method for manufacture of arbitrary described super-high strength cold rolled steel in the claim 1～7, comprise the steps:
Smelting, casting, hot rolling and cold rolling; And
Continuous annealing: 780～880 ℃ of insulations; With the speed of 10～30 ℃/s with gas cooling to 700～750 ℃; Be cooled to 550～640 ℃ so that the cooling rate of 60～200 ℃/s is jet then, be cooled to below 100 ℃ greater than 500 ℃/s with cooling rate then, behind last reheat to 150～250 ℃ tempering 60～300s; Wash through weak acid, smooth through 0～0.6% again.
9. the method for manufacture of super-high strength cold rolled steel as claimed in claim 8 is characterized in that, continuous annealing: 800～850 ℃ of insulations; With the speed of 10～30 ℃/s with gas cooling to 700～750 ℃; Be cooled to 580～620 ℃ so that the cooling rate of 100～200 ℃/s is jet then, be cooled to below 100 ℃ greater than 500 ℃/s with cooling rate then, behind last reheat to 180～220 ℃ tempering 60～200s; Wash through weak acid, smooth through 0～0.4% again.
10. like the method for manufacture of claim 8 or 9 described super-high strength cold rolled steels, it is characterized in that the hot rolled finishing temperature is 830～930 ℃, coiling temperature is 550～650 ℃.
11. the method for manufacture like claim 8 or 9 described super-high strength cold rolled steels is characterized in that, cold rolling draft is 40～70%.
12. the method for manufacture of super-high strength cold rolled steel as claimed in claim 10 is characterized in that, cold rolling draft is 40～70%.
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| CN102534373B (en) * | 2012-01-31 | 2014-07-23 | 宝山钢铁股份有限公司 | Super-high strength cold rolled steel belt suitable for rolling formation and manufacture method of super-high strength cold rolled steel belt |
| KR102060534B1 (en) * | 2012-03-30 | 2019-12-30 | 뵈스트알파인 스탈 게엠베하 | High strength cold rolled steel sheet and method of producing such steel sheet |
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| CN113877980A (en) * | 2021-10-22 | 2022-01-04 | 西北稀有金属材料研究院宁夏有限公司 | Beryllium window material and preparation method thereof |
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