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CN107829027A - A kind of Thin Specs 780MPa levels dual phase steel and its processing method - Google Patents

A kind of Thin Specs 780MPa levels dual phase steel and its processing method Download PDF

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Publication number
CN107829027A
CN107829027A CN201710978892.6A CN201710978892A CN107829027A CN 107829027 A CN107829027 A CN 107829027A CN 201710978892 A CN201710978892 A CN 201710978892A CN 107829027 A CN107829027 A CN 107829027A
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China
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dual phase
steel
processing method
thin specs
780mpa
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CN201710978892.6A
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CN107829027B (en
Inventor
刘斌
毛新平
徐进桥
刘永前
汪水泽
朱万军
王成
彭浩
韩荣东
魏星
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Wuhan Iron and Steel Co Ltd
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Wuhan Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

The invention discloses a kind of Thin Specs 780MPa levels dual phase steel and its processing method, belong to technical field of steel rolling.According to mass percent, the chemical composition of the dual phase steel is：C：0.05%~0.08%, Si：0.60%~1.00%, Mn：1.40%~1.80%, P≤0.015%, S≤0.004%, Cr：0.30%~0.70%, Als：0.020%~0.060%, surplus is Fe and inevitable impurity.It uses bar strip continuous casting and rolling flow path to produce, and processing method includes smelting, refining, CSP, cools down, batches, formation process；The stable manufacture of batch of the 3.0mm of thickness 1.0 Thin Specs 780MPa level dual phase steels is finally obtained, reduces production cost, and there is excellent comprehensive mechanical property, alternative cold-rolled biphase steel is used to manufacture passenger vehicle body structural member.

Description

A kind of Thin Specs 780MPa levels dual phase steel and its processing method
Technical field
The present invention relates to technical field of steel rolling, more particularly to a kind of Thin Specs 780MPa levels dual phase steel and its processing method.
Background technology
In recent years, Domestic Automotive Industry is grown continuously and fast, and tremendous influence is brought to social energy resource supply and environmental protection. For tackle environmental protection pressure, country promulgate a series of programmatic documents successively, explicitly point out China's manufacturing industry should accelerate green manufacturing, The transition paces of ecodevelopment.Now there are some researches show lightweight is to realize the most effective measure of automotive energy-saving emission-reducing, ferrous materials High strengthening be automobile lightweight important technology path.Greenization, high performance are as automobile steel iron material Development trend.
The advanced high-strength steel of traditional automobile using, the particularly advanced high-strength steel of below thickness 1.5mm, using hot rolling+cold rolling Manufacturing process, manufacturing process length, complex procedures, high energy consumption, face huge from automobile industry green manufacturing and cost of material Challenge.The dual phase steel of automotive body structure is presently used for, from composition, mostly containing the precious alloys such as Mo, Nb, Cu member Element, cost of alloy are higher；From the point of view of production technology, cold-rolled products production procedure energy consumption is big, cost is high, and hot rolling technology production The most thin use demand for being only 1.5mm, the following Ultra-thin dual phase steels of thickness 1.5mm can not being met of belt steel thickness.Therefore, how Develop greenization, low cost, the new automobile of Thin Specs become one brand-new problem of steel industry with advanced high-strength steel.
The content of the invention
It is an object of the invention to provide a kind of Thin Specs 780MPa level dual phase steels, without the precious alloys such as Mo, Nb, Cu member Element, cost of alloy is reduced, and performance disclosure satisfy that the use demand of automobile using high-strength steel.
It is a further object of the present invention to provide a kind of processing method of Thin Specs 780MPa level dual phase steels, connected using sheet billet Tandem rolling flow production thickness 1.0-3.0mm Thin Specs dual phase steel is cast to substitute cold-rolled products, reduces production cost, and have Excellent comprehensive mechanical property.
To achieve the above object, the invention provides a kind of Thin Specs 780MPa level dual phase steels, according to mass percent, institute The chemical composition for stating dual phase steel is：C：0.05%~0.08%, Si：0.60%~1.00%, Mn：1.40%~1.80%, P≤ 0.015%, S≤0.004%, Cr：0.30%~0.70%, Als：0.020%~0.060%, surplus is for Fe and unavoidably Impurity.
Further, the internal microstructure of the dual phase steel is ferrite+martensite.
Further, the internal microstructure of the dual phase steel by volume fraction be 60%~70% ferrite and 30% ~40% martensite composition.
Present invention also offers a kind of processing method of above-mentioned Thin Specs 780MPa level dual phase steels, the processing method is based on Bar strip continuous casting and rolling flow path, including：
Molten iron is smelted；
Molten iron after smelting is refined, obtains the molten steel after Alloying Treatment；
CSP is carried out to the molten steel, obtains coil of strip；Wherein, the heating-up temperature of the continuous casting and rolling is 1150~1230 DEG C, using constant speed rolling, mill speed is 5.0~10.0m/s；
The coil of strip is cooled down and batched；Wherein, the cooling uses the sub-sectional cooling of " water cooling+air cooling+water cooling " Mode, first paragraph water cooling speed are 40~120 DEG C/s, are cooled to 640~710 DEG C, subsequent 3.0~10.0s of air cooling, second segment water Speed of cooling is 120~200 DEG C/s, is cooled to≤200 DEG C and is batched；
Smooth processing is carried out to batching rear coil of strip, smooth power control is 80~220 tons, and it is 1.0~3.0mm's to obtain thickness Finished steel plate.
Preferably, the heating-up temperature of the CSP be 1190~1230 DEG C, mill speed be 5.5~ 10.0m/s；And/or first paragraph water cooling speed is 60~120 DEG C/s, 670~690 DEG C, subsequent 3.2~8.0s of air cooling are cooled to, Second segment water cooling speed is 120~150 DEG C/s, is cooled to≤180 DEG C and is batched；And/or smooth power is 150~220 tons.
It is furthermore preferred that for below thickness 1.5mm dual phase steel, heating and temperature control is 1200~1230 DEG C；Rolling speed Spend for 8.0~10.0m/s, while it is 90~120 DEG C/s to control after rolling first paragraph water cooling speed；The control of smooth power for 160~ 220 tons.
Preferably, 50~150mm of slab thickness in the continuous casting and rolling, it is 3.0~8.0m/min to control pulling speed of continuous casting.
It is furthermore preferred that 50~70mm of slab thickness, it is 4.0~5.0m/min to control pulling speed of continuous casting.
Preferably, the finishing temperature of the continuous casting and rolling is 800~880 DEG C.
Preferably, the internal microstructure of the dual phase steel is ferrite+martensite, and/or tensile strength >=780MPa, And/or yield strength >=420MPa.
One or more of the embodiment of the present application technical scheme, has at least the following technical effects or advantages：
1st, the Thin Specs 780MPa level dual phase steels that the embodiment of the present application provides, using the simple alloying component of C-Mn-Cr systems, Add the elements such as Si, Al simultaneously；Carbon content influences Martensite Volume Fraction, can improve the tensile strength of steel, and Mn can improve intensity And toughness, Cr can hinder the diffusion of carbon atom, Si can purify ferritic structure, under each element collective effect, ensure final material The mechanical property and cold formability energy of material, obtain the dual phase steel of Thin Specs 780MPa levels.
2nd, the processing method for the Thin Specs 780MPa level dual phase steels that the embodiment of the present application provides, using CSP Flow, by the control to heating-up temperature, constant speed rolling process and the type of cooling in production technology, steel plate is set to obtain rationally ratio Ferrite+martensitic structure of example, realize that the batch of thickness 1.0-3.0mm Thin Specs dual phase steel is stable and manufacture, shorten system Flow is made, reduces production cost, and there is excellent comprehensive mechanical property, alternative cold-rolled products, disclosure satisfy that automobile using The use demand of high-strength steel.
Brief description of the drawings
Fig. 1 is the processing method flow chart of the embodiment of the present application Thin Specs 780MPa level dual phase steels；
Fig. 2 is the metallographic structure photo for the dual phase steel that the embodiment of the present application 1 obtains.
Embodiment
The embodiment of the present application provides a kind of Thin Specs 780MPa levels dual phase steel and its processing method, is connected using sheet blank continuous casting Flow production thickness 1.0-3.0mm Thin Specs dual phase steel is rolled, reduces production cost, and there is excellent synthesis mechanical property Energy.
Technical scheme is described in detail below by accompanying drawing and specific embodiment, it should be understood that the application Specific features in embodiment and embodiment are the detailed description to technical scheme, rather than to present techniques The restriction of scheme, in the case where not conflicting, the technical characteristic in the embodiment of the present application and embodiment can be combined with each other.
The terms "and/or", only a kind of incidence relation for describing affiliated partner, expression may have three kinds of passes System, for example, A and/or B, can be represented：Individualism A, while A and B be present, these three situations of individualism B.In addition, herein Middle character "/", it is a kind of relation of "or" to typically represent forward-backward correlation object.
To achieve the above object, the embodiment of the present application provides a kind of Thin Specs 780MPa level dual phase steels, according to quality percentage Than the chemical composition of the dual phase steel is：C：0.05%~0.08%, Si：0.60%~1.00%, Mn：1.40%~ 1.80%, P≤0.015%, S≤0.004%, Cr：0.30%~0.70%, Als：0.020%~0.060%, surplus Fe And inevitable impurity.Preferably, in the dual phase steel C content be 0.06%~0.07%, Si contents be 0.85%~ 1.00%, Mn content are that 1.60%~1.70%, Cr contents are 0.43%~0.60%.
In the present embodiment, the internal microstructure of the dual phase steel is ferrite+martensite.
Preferably, the internal microstructure of the dual phase steel by volume fraction be 60%~70% ferrite and 30%~ 40% martensite composition.The organization type of the ratio can ensure tensile strength >=780MPa of dual phase steel, while have preferably Cold formability energy.
In the present embodiment, the thickness of the dual phase steel is 1.0~3.0mm.
The application forms the dual phase steel of above chemical composition by optimized alloy element, is to be based on following principle：
It is 0.05%~0.08% that the embodiment of the present application, which controls C element content range, and carbon can improve geneva in dual phase steel Body hardness, and the volume fraction of martensite is influenceed, so that the tensile strength of material reaches more than 780MPa levels.According to this steel grade Application, be mainly used in processing the part such as body structural member, it is necessary to carry out largely Pressing Deformation processing, therefore will Material is sought while intensity requirement is met, there is good cold formability energy.If carbon content is less than 0.05%, martensite Hardness can reduce, and under the conditions of certain component, the tensile strength of material does not reach standard requirement；If carbon content is more than 0.08%, then it can not meet the favorable forming property of material, while can also make molten steel that peritectic reaction occur in casting cycle, increase Add continuous casting bleed-out risk.So carbon content is limited to 0.05~0.08% scope.
It is 0.60%~1.00% that the embodiment of the present application, which controls Si element content ranges, and silicon accelerates carbon to Austria in dual phase steel The segregation of family name's body, makes ferrite further purify, the generation of thick carbide when exempting gap solution strengthening and can avoid cooling, The silicon being dissolved into simultaneously in ferrite can influence interaction of dislocation, increase under work hardening rate and given strength level Uniformly extension.If silicone content is more than 1.00%, the removal difficulty of material surface iron scale can be increased, influence surface quality； If silicone content is less than 0.60%, can not meet to strengthen effect.So silicone content is limited to 0.60~1.00% scope.
It is 1.40%~1.80% that the embodiment of the present application, which controls Mn element content ranges, and manganese is to improve intensity and toughness most to have The element of effect, perlitic transformation can be effectively postponed in dual phase steel.If its content is less than 1.40%, material can not be met Intensity requirement；But the manganese of excessive addition, ferritic precipitation can be suppressed in dual phase steel, Given this will be defined to thereon 1.80%.So manganese content is limited to 1.40~1.80% scopes.
The embodiment of the present application control P element content≤0.015%, P is harmful element, in order to avoid the weldability of material Energy, stamping formabilily, toughness, suitability for secondary processing deteriorate, by the control of its content below 0.015%.
The embodiment of the present application controls S constituent content≤0.004%, and the sulphur in steel often exists with the oxide morphology of manganese, this Kind sulphide inculsion is anisotropy that is very unfavorable, and causing performance to the impact flexibility of steel, therefore, need to be contained sulphur in steel Amount controls more low better.
It is 0.30%~0.70% that the embodiment of the present application, which controls Cr element content ranges, and chromium is carbide former, with The affinity of carbon is stronger, can hinder the diffusion of carbon atom, along with the comprehensive function of manganese, makes pearlite and bainite transformation notable Hysteresis, dual phase steel is produced favourable.When chromium content is less than 0.30%, it is impossible to play its effect；It is full that chromium content is more than 0.70% Sufficient requirement, cost increase can be made by continuing addition.Therefore chromium content is controlled 0.30~0.70%.
It is 0.020%~0.060% that the embodiment of the present application, which controls Al element content ranges, and aluminium is added for deoxidation , when Als contents are less than 0.020%, it is impossible to play its effect；On the other hand, because the aluminium of excessive addition easily forms oxygen Change aluminium agglomerate, so, it is specified that the Als upper limits are 0.060%.
The dual phase steel of the embodiment of the present application is made up of above-mentioned chemical composition, from raising formability of materials, the viewpoint of economy Set out, be not added with the expensive alloying elements such as Nb, Ti, Cu, Ni, Mo.
By the above as can be seen that the embodiment of the present application ensures by using the simple alloying component of C-Mn-Cr systems Steel plate has good solderability, while adds the elements such as Si and improve stability, under each element collective effect, ensures most The mechanical property and cold formability energy of whole material, significantly reduce cost of alloy；Designed using mentioned component, can obtain thickness is 1.0~3.0mm thin specification steel plate.Tensile strength >=780MPa of dual phase steel, yield strength >=420MPa, elongation percentage A50≥ 16%, yield tensile ratio≤0.60,180 ° cross bending test meets that Bend diameter D=1.5a is qualified.
The embodiment of the present application additionally provides a kind of processing method of above-mentioned Thin Specs 780MPa level dual phase steels, including smelt → Refining → CSP → cools down → batched → formation process, as shown in figure 1, comprising the following steps that：
Step S110：Molten iron is smelted；Preferably, desulfurization process is carried out to molten iron before smelting；
Step S120：Molten iron after smelting is refined, obtains the molten steel after Alloying Treatment；
Specifically, the molten iron after converter smelting enters LF stoves or RH stove refining treatments, refining process Alloying Treatment The chemical composition of molten steel is afterwards：C：0.05%~0.08%, Si：0.60%~1.00%, Mn：1.40%~1.80%, P≤ 0.015%, S≤0.004%, Cr：0.30%~0.70%, Als：0.020%~0.060%, surplus is for Fe and unavoidably Impurity.
Step S130：CSP is carried out to the molten steel, obtains coil of strip；
Specifically, molten steel is subjected to CSP production：Steel billet 50~150mm of thickness of casting, continuous casting are drawn 3.0~8.0m/min of speed；Strand is heated in soaking pit, and heating and temperature control is at 1150~1230 DEG C；In 7 frame finish rolling Rolled in machine, constant speed rolling is used according to thickness specification, mill speed is controlled in 5.0~10.0m/s, finishing temperature control At 800~880 DEG C, 1.0~3.0mm of rolling thickness.Wherein, pulling speed of continuous casting is controlled in 3.0~8.0m/min, is to improve steel Base enters the temperature of soaking pit, so as to reduce the energy consumption of soaking pit, reduces cost；Coil of strip is according to final finished thickness, rolling speed Degree is controlled in 5.0~10.0m/s, is to ensure during follow-up sub-sectional cooling, has time enough to carry out ferrite Transformation, so as to obtain the ferritic structure of proper ratio.
Preferably, steel billet 50~70mm of thickness of casting, 4.0~5.0m/min of pulling speed of continuous casting, soaking pit heating-up temperature 1190~1230 DEG C, 5.5~10.0m/s of mill speed, 800~840 DEG C of finishing temperature.
Step S140：The coil of strip is cooled down and batched；
Specifically, the sub-sectional cooling mode to the coil of strip after rolling using " water cooling+air cooling+water cooling "：First paragraph water cooling Speed is 40~120 DEG C/s, is cooled to 640~710 DEG C, followed by air cooling, 3.0~10.0s of air cooling time, second segment water cooling Speed is 120~200 DEG C/s, is cooled to≤200 DEG C and is batched；Control cooler-water temperature≤30 DEG C.Wherein, using " water cooling+ Air cooling+water cooling " sub-sectional cooling technique, first paragraph Cooling Process are 40~120 DEG C/sec of progress fast quickly coolings in front end according to cooling velocity But, temperature is cooled to as 640~710 DEG C, is to ensure to be cooled down in time when steel crystal grain does not have started and grown up, avoid The generation of coarse grain, material is set to obtain tiny austenitic grain structure；3.0~10.0s of air cooling so that partial austenitic group Knit and be changed into ferrite；Second segment Cooling Process cooling velocity is 120~200 DEG C/s, is cooled to≤200 DEG C and is batched, is made The austenite structure fast transition that not change in the air cooling stage is martensitic structure so that steel finally obtain ferrite+ The duplex structure of martensite.Control cooler-water temperature≤30 DEG C are to ensure cooling velocity during each section of cooling.
Preferably, first paragraph water cooling speed is 60~120 DEG C/s, is cooled to 670~690 DEG C, followed by air cooling, air cooling 3.2~8.0s of time, second segment water cooling speed are 120~150 DEG C/s, are cooled to≤180 DEG C and are batched；Control cooling water water Temperature≤25 DEG C.
Step S150：Smooth processing is carried out to batching rear coil of strip, obtains the finished steel plate that thickness is 1.0~3.0mm.
Specifically, the smooth power for smooth processing being carried out to coil of strip is 80~220 tons, final to obtain 1.0~3.0mm of thickness Internal microstructure be ferrite+martensite dual phase steel.Wherein, it is smooth processing be in order to improve the plate shape of hot-strip, Reach cold-rolled products requirement；Simultaneously because dual phase steel has higher initial manufacture hardening ratio, it is necessary to be carried out to smooth power Limitation, therefore according to the smooth power of thickness control of finished steel coils at 80~220 tons.Preferably, smooth power is 150~220 tons.
It is further preferred that for the dual phase steel of the following Ultra-thins of thickness 1.5mm, heating and temperature control 1200~ 1230 DEG C, it can effectively reduce operation of rolling load；Mill speed is 8.0~10.0m/s, while first paragraph water cooling is controlled after rolling Speed is 90~120 DEG C/s, strip can be made to keep the stable ferritic transformation time in cooling procedure, so as to improve material Stabilizability；Using flexible planar, smooth power is 160~220 tons.
By the above as can be seen that the application provide dual phase steel processing method, based on CSP Flow, by the control to heating-up temperature, constant speed rolling process and the type of cooling in production technology, make steel band in cooling procedure It is middle to be kept for the stable ferritic transformation time, so as to improve material property stability, the final ferrite+horse for obtaining rational proportion Family name's body tissue.The steel plate that thickness is 1.0~3.0mm, the dual phase steel produced according to the present embodiment can be produced by the above method With following performance：Tensile strength >=780MPa, yield strength >=420MPa, elongation percentage A50mm>=16%, yield tensile ratio≤0.60； Materials microstructure is ferrite and martensite duplex structure.Product possesses the spies such as inexpensive, thin or very narrow thickness, low yield strength ratio Point, cold-rolled biphase steel can be substituted and be used to manufacture passenger vehicle body structural member.
It is for a more detailed description to the application by the following examples.These embodiments are only to the optimal embodiment party of the present invention The description of formula, there is not any limitation to the scope of the present invention.
Molten iron enters LF stoves or RH stove refining treatments after converter smelting, and refining process carries out the steel after Alloying Treatment Hydrochemical Composition is as shown in table 1.
The embodiment two-phase composition of steel of table 1 (mass fraction %, surplus are Fe and inevitable impurity)
The molten steel of heterogeneity shown in table 1 is subjected to CSP production, section cooling, batched and smooth Processing, main technologic parameters are as shown in table 2.
The embodiment main technologic parameters list of table 2
The two-phase Steel Properties of the embodiment of the present application are as shown in table 3.
The embodiment main performance list of table 3
As can be seen from Table 3, the dual phase steel for the thickness specification 1.0-3.0mm that embodiment 1-8 is obtained can meet that surrender is strong Spend RP0.2>=420Mpa, tensile strength Rm>=780MPa, elongation percentage A50>=16%, yield tensile ratio≤0.60.Fig. 2 is implemented for the application The metallographic structure figure for the dual phase steel that example obtains, as seen from Figure 2：The strip is organized as ferrite+martensite, and ferrite is brilliant 12 grades of granularity.The yield strength of comparative example is higher, the problem of resilience is larger, cold formability energy be present in punching press cold forming part It is bad.
The above results show, thickness specification can be obtained using the composition design in the embodiment of the present application and technology controlling and process 1.0-3.0mm the dual phase steel of tensile strength 780MPa levels.
One or more of the embodiment of the present application technical scheme, has at least the following technical effects or advantages：
1st, low cost manufacture is realized.On the one hand, the embodiment of the present application is realized using the simple alloying component of C-Mn-Cr systems The production of 780MPa dual phase steels, significantly reduces cost of alloy；Another aspect the embodiment of the present application uses CSP Flow produces the advanced high-strength steel of automobile using, shortens manufacturing process, production process cost can be greatly reduced.
2nd, production process greenization.The embodiment of the present application is steamed automobile-used advanced height using bar strip continuous casting and rolling flow path next life Strong steel substitutes traditional cold-rolled products, eliminates the cold rolling process of complexity, manufacturing process is greatly shortened, reduce energy consumption water consume and All kinds of waste discharges, ton steel comprehensive energy consumption can reduce by more than 70%, equivalent CO2Discharge capacity can reduce about 30%, realize green Manufacture.
3rd, the following Ultra-thin two-phase steel makings of thickness 1.5mm are realized.Produced using bar strip continuous casting and rolling flow path very thin Specification dual phase steel, when belt steel thickness is reduced to 1.0mm by 1.5mm, there is that rolling load is high, ferritic transformation is unstable and plate shape Fluctuate the difficult point such as big.The embodiment of the present application, can be effective using " high-temperature heating-constant speed rolling-quick cooling-flexible planar " technology Reduce below 1.5mm rolling load of strip hot rolling, stable ferritic transformation time, improve Thin Specs dual phase steel plate shape, realize thickness The stable manufacture of below 1.5mm Ultra-thins dual phase steel batch.
It should be noted last that above embodiment is merely illustrative of the technical solution of the present invention and unrestricted, Although the present invention is described in detail with reference to example, it will be understood by those within the art that, can be to the present invention Technical scheme modify or equivalent substitution, without departing from the spirit and scope of technical solution of the present invention, it all should cover Among scope of the presently claimed invention.

Claims (10)

  1. A kind of 1. Thin Specs 780MPa level dual phase steels, it is characterised in that according to mass percent, the chemical composition of the dual phase steel For：C：0.05%~0.08%, Si：0.60%~1.00%, Mn：1.40%~1.80%, P≤0.015%, S≤ 0.004%, Cr：0.30%~0.70%, Als：0.020%~0.060%, surplus is Fe and inevitable impurity.
  2. 2. Thin Specs 780MPa level dual phase steels as claimed in claim 1, it is characterised in that micro- group of the inside of the dual phase steel It is woven to ferrite+martensite.
  3. 3. Thin Specs 780MPa level dual phase steels as claimed in claim 2, it is characterised in that micro- group of the inside of the dual phase steel Knit and be made up of volume fraction for 60%~70% ferrite and 30%~40% martensite.
  4. 4. the processing method of the Thin Specs 780MPa level dual phase steels as described in claim 1-3 any claims, its feature exist In, the processing method is based on bar strip continuous casting and rolling flow path, including：
    Molten iron is smelted；
    Molten iron after smelting is refined, obtains the molten steel after Alloying Treatment；
    CSP is carried out to the molten steel, obtains coil of strip；Wherein, the heating-up temperature of the continuous casting and rolling be 1150~ 1230 DEG C, using constant speed rolling, mill speed is 5.0~10.0m/s；
    The coil of strip is cooled down and batched；Wherein, the cooling uses the sub-sectional cooling mode of " water cooling+air cooling+water cooling ", First paragraph water cooling speed is 40~120 DEG C/s, is cooled to 640~710 DEG C, subsequent 3.0~10.0s of air cooling, second segment water cooling speed Spend for 120~200 DEG C/s, be cooled to≤200 DEG C and batched；
    Smooth processing is carried out to batching rear coil of strip, smooth power control is 80~220 tons, obtains the finished product that thickness is 1.0~3.0mm Steel plate.
  5. 5. the processing method of Thin Specs 780MPa level dual phase steels as claimed in claim 4, it is characterised in that the sheet billet connects The heating-up temperature for casting tandem rolling is 1190~1230 DEG C, and mill speed is 5.5~10.0m/s；And/or first paragraph water cooling speed is 60 ~120 DEG C/s, 670~690 DEG C, subsequent 3.2~8.0s of air cooling are cooled to, second segment water cooling speed is 120~150 DEG C/s, cold But batched to≤180 DEG C；And/or smooth power is 150~220 tons.
  6. 6. the processing method of Thin Specs 780MPa level dual phase steels as claimed in claim 4, it is characterised in that for thickness Below 1.5mm dual phase steel, heating and temperature control are 1200~1230 DEG C；Mill speed is 8.0~10.0m/s, while is being rolled It is 90~120 DEG C/s to control first paragraph water cooling speed afterwards；Smooth power control is 160~220 tons.
  7. 7. the processing method of the Thin Specs 780MPa level dual phase steels as described in one of claim 4-6, it is characterised in that described 50~150mm of slab thickness in continuous casting and rolling, it is 3.0~8.0m/min to control pulling speed of continuous casting.
  8. 8. the processing method of Thin Specs 780MPa level dual phase steels as claimed in claim 7, it is characterised in that slab thickness 50~ 70mm, it is 4.0~5.0m/min to control pulling speed of continuous casting.
  9. 9. the processing method of the Thin Specs 780MPa level dual phase steels as described in one of claim 4-6, it is characterised in that the company The finishing temperature for casting tandem rolling is 800~880 DEG C.
  10. 10. the processing method of the Thin Specs 780MPa level dual phase steels as described in one of claim 4-6, it is characterised in that described The internal microstructure of dual phase steel is ferrite+martensite, and/or tensile strength >=780MPa, and/or yield strength >= 420MPa。
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1970813A (en) * 2006-12-18 2007-05-30 马鞍山钢铁股份有限公司 Process for production of hot-rolled dual phase steel by continuous casting and continuous rolling of slab billet
US20140147329A1 (en) * 2012-11-28 2014-05-29 Hyun Jo Jun High silicon bearing dual phase steels with improved ductility
CN106086627A (en) * 2016-07-27 2016-11-09 武汉钢铁股份有限公司 A kind of 600MPa level hot-rolled dual-phase steel and production method thereof
CN106834915A (en) * 2016-12-06 2017-06-13 内蒙古包钢钢联股份有限公司 800MPa grades of hot-rolled dual-phase steel of 2 ~ 4mm thickness and its processing method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1970813A (en) * 2006-12-18 2007-05-30 马鞍山钢铁股份有限公司 Process for production of hot-rolled dual phase steel by continuous casting and continuous rolling of slab billet
US20140147329A1 (en) * 2012-11-28 2014-05-29 Hyun Jo Jun High silicon bearing dual phase steels with improved ductility
CN106086627A (en) * 2016-07-27 2016-11-09 武汉钢铁股份有限公司 A kind of 600MPa level hot-rolled dual-phase steel and production method thereof
CN106834915A (en) * 2016-12-06 2017-06-13 内蒙古包钢钢联股份有限公司 800MPa grades of hot-rolled dual-phase steel of 2 ~ 4mm thickness and its processing method

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