CN110129673A - A kind of 800MPa grades of high strength and ductility Q&P steel plate and preparation method thereof - Google Patents

A kind of 800MPa grades of high strength and ductility Q&P steel plate and preparation method thereof Download PDF

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CN110129673A
CN110129673A CN201910423065.XA CN201910423065A CN110129673A CN 110129673 A CN110129673 A CN 110129673A CN 201910423065 A CN201910423065 A CN 201910423065A CN 110129673 A CN110129673 A CN 110129673A
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rolling
steel
steel plate
pickling
preparation
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CN110129673B (en
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潘红波
沈晓辉
曹京华
刘永刚
潘烁
王会廷
詹华
闫军
肖洋洋
刘伟明
章静
曹杰
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Anhui University of Technology AHUT
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • 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
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D2211/001—Austenite
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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

Abstract

The present invention discloses a kind of 800MPa grades of high strength and ductility Q&P steel plate and preparation method thereof, belongs to cold rolled automobile steel production technical field.The chemical component weight percent of the steel plate are as follows: C:0.38~0.42%, Si:0:10~0.30%, Mn:0.80~1.20%, Al:2.80~3.20%, P≤0.020%, S≤0.0030%, N≤0.0060%, surplus are Fe and inevitable residual impurities element.Preparation method includes smelting, continuous casting, hot rolling, pickling, cold rolling, continuous annealing；Cold-reduced sheet is heated to 830~860 DEG C when continuous annealing；Then slowly cool to 700~730 DEG C；350~400 DEG C of progress overaging partition processing are finally cooled to fastly with the cooling rate of 40~60 DEG C/s.Q&P mechanical property of steel plate of the present invention is excellent, yield strength >=480MPa, tensile strength >=800MPa, elongation percentage >=25%, n >=0.20, yield tensile ratio≤0.75, and cold forming is functional.The present invention is of less demanding to technological equipment, is suitable for existing continuous annealing production line production.

Description

A kind of 800MPa grades of high strength and ductility Q & P steel plate and preparation method thereof
Technical field:
The invention belongs to cold rolled automobile steel production technical fields, and in particular to a kind of tensile strength 800MPa grades of high-strength modelings Product cold rolling Q&P steel plate and preparation method thereof.
Background technique:
In recent years, with the fast development of China's automobile industry and being becoming increasingly acute for energy and environmental problem, to improve Automobile fuel ecomomy simultaneously reduces CO2To cope with Global climate change, China " Passenger Car Fuel Consumption Standard consumption limit value " is provided for discharge, The passenger car average fuel consumption produced to the year two thousand twenty China will be down to 5 liters/hundred kilometers.Increasingly stringent discharge standard is to vapour More stringent requirements are proposed for vehicle manufacturer, also provides opportunity to develop to automotive material lightweight.100 kilograms of the every loss of weight of automobile, Oil consumption reduces by 0.64 liter/hundred kilometers, and CO2 emission reduces 1 kilogram.Therefore by mitigating the kerb weight of automobile, to mention The dynamic property of high automobile reduces fuel consumption, reduces exhaust emission, it has also become following development trend.Body lightening is most bright Aobvious feature is exactly the selection of material.Currently, be applied to light weight material in automobile mainly have high strength steel, aluminium alloy, magnesium alloy, Carbon fiber etc. is several.Since steel is compared with other competitive materials (such as aluminium, magnesium, carbon fiber reinforced polymer), manufacturing cost is low, Life cycle discharge simultaneously is few, therefore steel is still the best selection of auto industry.It is answered extensively moreover, steel has in automobile industry Experience, automobile industry are familiar with its Property comparison；These will greatly reduce new design, and manufacture, process and open with forming technique Send out cost.Production higher intensity and the steel of more dominance energy will be driven by automobile industry fuel economy and safety collision demand It is dynamic.
As the representative steel grade of the advanced high-strength steel of the third generation, Q&P steel is with higher in the case where adding a small amount of alloy Intensity and plasticity, i.e., excellent comprehensive performance, therefore cause the broad interest of metallurgy industry and automobile industry.At present for Q& The wide popularization and application of P steel mainly encounters two bottlenecks: (1) tradition Q&P steel is in process of production, preferable comprehensive in order to obtain Performance is closed, generally requires to be quenched in lower temperature, is then rapidly heated and carries out alloying element to higher partition temperature Partition, hardening heat often differ 100 DEG C or so with partition temperature, since traditional continuous annealing production line overaging section is without quick Induction heating function, therefore the technique is difficult to promote the use of in existing continuous annealing production line.(2) cold forming is come at present It says, the stamping equipment and mold ability to bear of automobile industry are existing for the steel grade of higher level generally at 600-800MPa grades Stamping equipment is difficult to meet its power and can require.Therefore exploitation adapts to metallurgy at present and auto industry production equipment capability requirement High strength and ductility Q&P steel has a very important significance the propulsion of current automotive light weight technology and safety with improvement.
The pertinent literature for being related to high strength and ductility Q&P steel at present is disclosed directly below: Chinese patent CN108193138A is disclosed 980MPa grades of automobile cold-rolled high-strength Q&P steel and its production method, mainly on traditional C/S iMn component base, suitably reduction Si Content is substituted with 0.5~1.0% Al, while being added to 0.04~0.07% microalloy element Nb.Wherein Si, Mn Content is relatively high, is easy to generate external oxidation in the production of traditional continuous annealing production line, causes surface color yellowing.China Patent CN105018843A discloses the Q&P steel and its manufacturing method of vanadium and the compound addition of titanium, intensity up to 1350~ 1450MPa, the high cold forming of intensity is difficult, is only used for simple components production.Chinese patent CN108660369A discloses anti- Quenching partition cold-rolled steel sheet of the tensile strength greater than 1180MPa and production method, Chinese patent CN103555902A disclose one kind The heat treatment process and Chinese patent CN103555894A of 980MPa grades of high strength and ductility automobile steels disclose a kind of Q&P980 steel Heat treatment process, quench in annealing process and differ greatly with partition temperature, to traditional continuous annealing production line batch metaplasia Production has larger difficulty.Chinese patent CN104988391A discloses a kind of 1200MPa grades of cold rolling Q&P steel and its manufacturing method, Quenching is differed greatly with partition temperature in annealing process, while requiring roller cold and water cooling during rapid cooling, continuous to current tradition Anneling production line cannot achieve.Chinese patent CN101487096A discloses a kind of low-alloy high-strength C-Mn-Al Q & P steel And its manufacturing method, add Al component system using low Si, wherein Al content is 1.0~1.5%, is quenched in heat treatment process Temperature is also larger with partition temperature, implements to acquire a certain degree of difficulty on traditional continuous annealing production line.Chinese patent CN103215491A discloses a kind of method for preparing carbon silicomanganese system Q&P steel using alloying element partition, the invention annealing temperature Up to 900~950 DEG C, need to be in 720~800 DEG C of pre- 250~600s of partition before annealing, while hardening heat and final partition temperature Poor 100 DEG C or more are spent, this cannot achieve in existing continuous annealing production line.
Above-mentioned technology is mainly that the intensity of Q&P steel is improved by various reinforcing means and stable austenite element, technique With plasticity.However for Q&P steel production for, in tensile strength 1000~1200MPa level range relatively easily design with Production, main remaining a small amount of alloying element of control and addition by routine CSiMn alloying element, it is appropriate to carry out to production technology Control can be obtained.But for 800MPa grades of Q&P steel, production acquires a certain degree of difficulty, using conventional CSiMn at fission System cannot achieve, and addition alloying element is few, be unable to satisfy the requirement of its harden ability；Addition alloying element is slightly higher, and intensity just reaches 1000MPa or more, it is therefore desirable to be realized using new component system with design concept.In addition to soaking temperature in above-mentioned technology Degree requires excessively high, cooling rate that too fast and quenching is required to differ greatly with partition temperature, on existing continuous annealing production line also very Hardly possible is realized.
Summary of the invention:
The present invention provides a kind of suitable prior art equipment for above-mentioned deficiency present in existing Q&P steel technology of preparing With the 800MPa grade high strength and ductility Q&P steel plate of the market demand and preparation method thereof, high strength and ductility Q&P steel plate of the present invention has good Cold formability energy, be suitable as the high-intensitive cold stamping structural member such as automobile A, B column and collision prevention girders and anti-striker.The method of the present invention Yield strength >=480MPa of prepared high strength and ductility Q&P steel plate, tensile strength >=800MPa, elongation percentage >=25%, n >= 0.20, yield tensile ratio≤0.75.
The chemical component of 800MPa grades of high strength and ductility Q&P steel plate provided by the present invention is by weight percent are as follows: C:0.38 ~0.42%, Si:0:10~0.30%, Mn:0.80~1.20%, Al:2.80~3.20%, P≤0.020%, S≤ 0.0030%, N≤0.0060%, surplus are Fe and inevitable residual impurities element.
The present invention provides a kind of preparation method of 800MPa grades of high strength and ductility Q&P steel plate, which includes smelting, being smart Refining, continuous casting, hot rolling, pickling, cold rolling and annealing, specific step is as follows for the preparation method:
(1) it smelts, smelting carries out in electric arc furnaces or converter, controls P≤0.02wt% in steel.
(2) it refining, refining uses LF and RH, in order to improve the comprehensive performance of slab and final product quality and final products, S, O, N impurity content in steel are eliminated as much as in refining process.
(3) continuous casting, continuous casting is poured using full guard and electromagnetic agitation, and direct hot charging is packed into after the slab well cutting after continuous casting Heating furnace；
(4) hot rolling, hot rolling heating temperature are 1300~1350 DEG C, and roughing rolls in austenite recrystallization area, rough rolling step Using 8~10 passages, austenite recrystallization area total reduction is greater than 70%, and workpiece thickness is 30~50mm, and finish rolling is in Ovshinsky The rolling of body Unhydrated cement, finish rolling stage use 6~7 passages, and austenite Unhydrated cement total reduction is greater than 80%, finish to gauge temperature Degree control is batched within the scope of 600~650 DEG C after being rolled to target thickness at 890~920 DEG C；
(5) pickling, pickling use plug-type pickling, and hot-strip is through hydrochloric acid trough pickling, to remove scale on surface；
(6) cold rolling, cold rolling carry out on single stand reversible rolling mill, and the operation of rolling uses the small pressure of multi-pass, under stagnation pressure Rate is 50~65%；
(7) it anneals, annealing uses continuous annealing furnace, and strip is heated to 170 with the rate of heat addition of 5~8 DEG C/s first It DEG C is preheated, strip is then further heated to by 830~860 DEG C of progress sammings with the rate of heat addition of 1.5~2.5 DEG C/s, Soaking time is 100~150s, is then cooled to 700~730 DEG C with the cooling rate of 4~6 DEG C/s, then passes through 30%H2+N2It is mixed It closes gas and 350~400 DEG C of 400~900s of Wetted constructures is cooled to the cooling rate of 40~60 DEG C/s, finally with 2~3 DEG C/s Rate be cooled to room temperature.
The present invention in order to guarantee 800MPa grades intensity, excellent comprehensive performance and processing performance, steel ingredient design On, the low manganese of carbon, the design of high Al ingredient in make full use of martensite to increase intensity, ferrite and austenite and increase plasticity Complex tissue toughening technology.Wherein the basic principle of each alloying element content design is as follows:
C:C is most economical effective intensified element in steel, and improves harden ability, forms martensite and stable austenite not Can or scarce alloying element, adding suitable C content in steel will not only be such that plasticity declines, but also because C during partition It is spread into austenite, the stability for improving austenite makes it that TRIP effect occur in deformation process, makes its plasticity instead It greatly improves, therefore its content cannot be too low.But too high levels can cause the weldability of steel and formability to deteriorate, so this hair It is bright to control C content within the scope of 0.38~0.42%.
Si: in steel plus silicon can improve purity of steel and deoxidation, and solution strengthening effect is played in steel, can also inhibit to be carbonized The effect that object is precipitated.Due to being added to higher Al content in the invention, adds certain Si and carry out deoxidation to prevent Al and O knot It closes and wadding flow phenomenon occurs, when silicone content is lower than 0.1%, it is difficult to obtain sufficient deoxidation effect.But silicone content is excessively high to be made Oxide skin viscosity when heating of plate blank is larger, and de-scaling is difficult after coming out of the stove, and it is serious to lead to roll rear surface of steel plate red scale, table Face is second-rate, while Si is easy to happen external oxidation reaction, is formed in belt steel surface under the weak reducing atmosphere of annealing process A thin layer of iron scale, to deteriorate the surface quality of steel plate, therefore the present invention Si content controlled 0.10~ Within the scope of 0.30%.
Mn: belonging to typical austenite stabilizer element, can significantly improve the harden ability of steel, can significantly postpone pearlite and Bainite transformation reduces the Critical cooling speed that martensite is formed；In addition Mn forms MnS in steel in conjunction with S to prevent steel from generating heat Crisp phenomenon.But high Mn content can also postpone ferritic precipitation, and in steel while postponing perlitic transformation The heart generates segregation, deteriorates its performance.Therefore the present invention is by the control of Mn content within the scope of 0.8~1.2%.
On the one hand Al:Al is conducive to loss of weight energy conservation as light element；Another aspect Al is ferrite former, is easy to It is dissolved to ferrite, and the chemical potential of C, Mn in ferrite can be effectively improved, in two-phase section annealing process, Al's adds Add and substantially speed up C, Mn and shifted into austenite, to increase the stability of austenite indirectly.Al keeps ferrite sufficiently " net Change ", avoid the generation of coarse carbide when the solid solution of a large amount of gaps and cooling of the C in ferrite.Al can also expand Fe-C The area α+γ of phasor, broadens the temperature range of tow-phase region heat treatment, is conducive to the stability and again for keeping product mechanical property Existing property.Al can significantly improve Ms point simultaneously, martensite can be obtained under higher hardening heat, while also ensuring the work of C It spends and is spread into austenite.In addition Al can inhibit the formation of carbide, expand C during partition into retained austenite It dissipates, stabilization of austenite is improved, to improve the strength and ductility product of steel.Compared with Si, Al can also improve surface quality.But it is excessively high Al can block the mouth of a river in continuous casting, increase the difficulty of continuous casting.In summary it acting on, the present invention controls Al content 3.8~ Within the scope of 3.2%.
N, S and P:N, S and P belong to impurity element in steel, deteriorate the plasticity and toughness of steel, in general content it is more low more It is good.
Influence of the process for making to product of the present invention:
Bessemerize and refining treatment: purpose is to ensure that the basis requirement of molten steel, removes oxygen, nitrogen, the hydrogen etc. in steel The objectionable impurities such as pernicious gas and P, S, and the necessary alloying element such as carbon, manganese, silicon, aluminium is added, carry out the adjustment of alloying element.
Continuous casting: guaranteeing that the uniform surface quality of slab internal component is good, and continuous casting is poured using full guard and electromagnetic agitation, Not only Al is avoided to aoxidize in casting process and the flow phenomenon that occurs to wad a quilt with cotton, reduce steel inclusion, improves slab quality, fragmentation branch It is brilliant；The good slab of continuous casting is directly subjected to hot charging, to reduce decrepitation.
Hot rolling: can occur austenite transformation to make as cast condition delta ferrite during heating, and thinning microstructure improves performance, By heating and temperature control at 1300~1350 DEG C, 2~3 hours are kept the temperature.Roughing is smaller using multi-pass in austenite recrystallization area Reduction ratio rolling, total reduction is greater than 70%, so that austenite structure sufficiently refines and prevents the operation of rolling from cracking defect. Finish rolling is rolled in austenite Unhydrated cement, and finishing temperature control prevents from rolling in two-phase section at 890~920 DEG C；Austenite is not Recrystallization zone total reduction is greater than 80%, to improve phase transformation nucleation point, thinning microstructure.It is carried out within the scope of 600~650 DEG C after rolling It batches, with further thinning microstructure.
Pickling: pickling uses plug-type pickling, and hot-strip is to remove scale on surface through hydrochloric acid turbulence acid dip Cold rolling is prepared.
Cold rolling: cold rolling carries out on single stand reversible rolling mill, and the operation of rolling uses the small pressure of multi-pass, and total reduction is 50-65% mainly avoids cracking cracking phenomena during depressing greatly；
Annealing: annealing uses continuous annealing furnace, and annealing temperature is 830~860 DEG C, main to control ferrite and austenite Content；Slow cooling temperature is 700~730 DEG C, and a certain amount of ferrite is on the one hand precipitated, on the other hand reduces fast cold pressure, prevents It is shaken during rapid cooling bent with wooden dipper；Using 30%H2+N2Mixed gas is cooled to 350~400 DEG C with the cooling rate of 40~60 DEG C/s 400~900s of Wetted constructures, mainly acquisition martensitic structure and C partition stable austenite, improve residual austenite content With stability, improve product comprehensive performance.
The present invention has following technical characterstic:
Ingredient of the present invention and technological design it is easy to implement and control, technology controlling and process is simple and easy to do, solves existing Q&P technique is to the harsh problem such as high cooling rate, low hardening heat and higher partition temperature.The present invention proposes that a kind of completely new alloy is set Thought and theory are counted, solves the problems, such as that existing CSiMn component system can not produce 800MPa grades of Q&P steel.With existing CSiMn at Fission system compares, it is therefore prevented that Si and O in belt steel surface in conjunction with form oxide, improve strip surface quality.With existing Q&P work Skill is compared, and it is not necessary that roller is cold and water cooling, and hardening heat is consistent with partition temperature, solves existing continuous annealing production line overaging section Without quick induction heating problem, mass production can be stablized without being transformed in existing continuous annealing production line.With it is existing DP800 is compared, and under intensity unanimous circumstances, plasticity, n value and strength and ductility product are increased substantially, and it is opposite to be conducive to punching press The safety of complicated part and raising collision.
Specific embodiment:
Invention is further described in detail combined with specific embodiments below.
It matches by the chemical component of table 1 and is smelted in vacuum induction melting furnace, and pour into ingot casting, then forge ingot casting It makes to 80mm heavy slab, carries out hot rolling, pickling, cold rolling and continuous annealing in laboratory and simulate, technique is as shown in table 2, hot rolling It batches and (batch-type furnace set temperature is consistent with coiling temperature, furnace cooling after heat preservation 2 hours) is simulated using chamber type electric resistance furnace； Continuous annealing is carried out on continuous annealing simulator using the technique of setting.
The present invention is measured according to GB/T228-2010 " metal material stretching test part 1: room temperature test method " to implement Every mechanical property of example 1-5 steel plate, the results are shown in Table 3.
The chemical component of 800MPa grades of high strength and ductility Q&P steel plate provided by the present invention is by weight percent are as follows: C:0.38 ~0.42%, Si:0:10~0.30%, Mn:0.80~1.20%, Al:2.80~3.20%, P≤0.020%, S≤ 0.0030%, N≤0.0060%, surplus are Fe and inevitable residual impurities element.Finishing temperature is 890~920 DEG C, is rolled It is batched at 600~650 DEG C, then through pickling, cold rolling, is carried out at continous way annealing after strip is rolled to target thickness afterwards Reason, specific annealing process is as follows: strip is heated to 170 DEG C with the rate of heat addition of 5~8 DEG C/s first and is preheated, then with Strip is further heated to 830~860 DEG C of progress sammings by the rate of heat addition of 1.5~2.5 DEG C/s, and soaking time is 100~ Then 150s is cooled to 700~730 DEG C with the cooling rate of 4~6 DEG C/s, then passes through 30%H2+N2Mixed gas is with 40~60 DEG C/cooling rate of s is cooled to 350~400 DEG C of 400~900s of Wetted constructures, room temperature is finally cooled to the rate of 2~3 DEG C/s.
The chemical component (weight percent %) of 1 1-5 of the embodiment of the present invention of table
Embodiment C Si Mn P S Al N
1 0.39 0.12 0.92 0.010 0.0021 2.93 0.0052
2 0.38 0.25 1.03 0.015 0.0028 3.12 0.0043
3 0.40 0.20 1.16 0.013 0.0024 2.86 0.0055
4 0.41 0.15 1.05 0.017 0.0027 3.17 0.0046
5 0.39 0.23 0.86 0.014 0.0026 3.09 0.0048
The technological parameter of 2 1-5 of the embodiment of the present invention of table
The mechanical property of the Q&P steel plate of the present invention of table 3
Embodiment Yield strength/MPa Tensile strength/MPa Elongation percentage A50/ % n Strength and ductility product/GPa%
1 486.7 801.5 27.8 0.26 22.28
2 497.4 814.6 26.6 0.26 21.67
3 571.6 809.5 29.7 0.22 24.04
4 580.3 816.5 30.4 0.21 24.82
5 544.8 833.7 27.8 0.25 23.18

Claims (2)

1. a kind of 800MPa grades of high strength and ductility Q&P steel plate, it is characterised in that the chemical component of the steel plate is by weight percent are as follows:
C:0.38~0.42%, Si:0:10~0.30%, Mn:0.80~1.20%, Al:2.80~3.20%, P≤ 0.020%, S≤0.0030%, N≤0.0060%, surplus are Fe and inevitable residual impurities element.
2. the preparation method of 800MPa grades of high strength and ductility Q&P steel plate as described in claim 1, it is characterised in that the preparation method packet Smelting, refining, continuous casting, hot rolling, pickling, cold rolling and annealing are included, specific step is as follows for the preparation method:
(1) it smelts, smelting carries out in electric arc furnaces or converter, controls P≤0.02wt% in steel；
(2) it refines, refining uses LF and RH；
(3) continuous casting, continuous casting is poured using full guard and electromagnetic agitation, and direct hot charging is packed into heating after the slab well cutting after continuous casting Furnace；
(4) hot rolling, hot rolling heating temperature are 1300~1350 DEG C, and roughing rolls in austenite recrystallization area, and rough rolling step uses 8 ~10 passages, austenite recrystallization area total reduction are greater than 70%, and workpiece thickness is 30~50mm, finish rolling austenite not again Crystal region rolling, finish rolling stage use 6~7 passages, and austenite Unhydrated cement total reduction is greater than 80%, finishing temperature control At 890~920 DEG C, batched within the scope of 600~650 DEG C after being rolled to target thickness；
(5) pickling, pickling use plug-type pickling, and hot-strip is through hydrochloric acid trough pickling, to remove scale on surface；
(6) cold rolling, cold rolling carry out on single stand reversible rolling mill, and the operation of rolling uses the small pressure of multi-pass, and total reduction is 50~65%；
(7) anneal, annealing use continuous annealing furnace, first by strip with the rate of heat addition of 5~8 DEG C/s be heated to 170 DEG C into Row preheating, is then further heated to 830~860 DEG C of progress sammings for strip with the rate of heat addition of 1.5~2.5 DEG C/s, keeps the temperature Time is 100~150s, is then cooled to 700~730 DEG C with the cooling rate of 4~6 DEG C/s, then passes through 30%H2+N2Gaseous mixture Body is cooled to 350~400 DEG C of 400~900s of Wetted constructures with the cooling rate of 40~60 DEG C/s, finally with the speed of 2~3 DEG C/s Rate is cooled to room temperature.
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