CN116240462A - 800 MPa-grade hot-rolled pickled Q & P steel and production method thereof - Google Patents
800 MPa-grade hot-rolled pickled Q & P steel and production method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 103
- 239000010959 steel Substances 0.000 title claims abstract description 103
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 7
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 7
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 6
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 5
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims abstract description 4
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 4
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 4
- 239000000126 substance Substances 0.000 claims abstract description 4
- 238000001816 cooling Methods 0.000 claims description 39
- 229910001566 austenite Inorganic materials 0.000 claims description 22
- 238000005554 pickling Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 17
- 229910000734 martensite Inorganic materials 0.000 claims description 13
- 230000008569 process Effects 0.000 claims description 12
- 238000005096 rolling process Methods 0.000 claims description 12
- 229910000859 α-Fe Inorganic materials 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 4
- 230000000717 retained effect Effects 0.000 claims description 4
- 238000005266 casting Methods 0.000 claims description 3
- 230000003746 surface roughness Effects 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- 239000011572 manganese Substances 0.000 description 5
- 238000003723 Smelting Methods 0.000 description 4
- 238000005098 hot rolling Methods 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910001567 cementite Inorganic materials 0.000 description 3
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005097 cold rolling Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 238000000638 solvent extraction Methods 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 229910017112 Fe—C Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
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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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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- 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
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- 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
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- 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
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- 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
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- 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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- 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
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- Y02P10/20—Recycling
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Abstract
The invention relates to 800MPa hot-rolled pickled Q & P steel and a production method thereof, wherein the steel comprises the following chemical components in percentage by weight: 0.14 to 0.16 percent of C, less than or equal to 0.10 percent of Si, 1.40 to 1.60 percent of Mn, 0.045 to 0.065 percent of P, less than or equal to 0.005 percent of S, 0.02 to 0.05 percent of Al, 0.02 to 0.04 percent of Nb, 0.015 to 0.035 percent of V, 0.15 to 0.30 percent of Mo, less than or equal to 0.006 percent of N, and the balance of Fe and unavoidable impurities. The invention aims to improve the plasticity of the steel plate and the surface quality of the steel plate on the premise of ensuring the mechanical property of the steel plate.
Description
Technical Field
The invention belongs to the technical field of steel rolling, and particularly relates to 800 MPa-grade hot-rolled pickled Q & P steel and a production method thereof, wherein the 800 MPa-grade hot-rolled pickled Q & P steel is mainly suitable for manufacturing automobile parts with high requirements on safety and surface quality.
Background
The Q & P steel is one of the third generation advanced high-strength steel for automobiles, and is mainly used for producing high-strength steel with TRIP effect, high strength and high plasticity (toughness) in cooperation by controlling the volume fraction of carbon-rich residual austenite and martensite at room temperature through a quenching and partitioning process, and is mainly applied to safety parts, structural parts and the like of automobiles, and has good formability and collision safety. At present, Q & P steel is mainly produced by adopting a cold rolling heat treatment method, namely, hot rolling raw materials are reheated to an austenite region for heat preservation after cold rolling, and then quenching and partitioning are carried out to obtain the Q & P steel plate. With the development of technology, the methods for producing Q & P steel by hot rolling are gradually increasing.
In the patent document with publication number of CN103805851B, an ultra-high strength low-cost hot rolled Q & P steel and a manufacturing method thereof are proposed, wherein the proposed hot rolled steel plate has ultra-high strength of more than 1400MPa and elongation of more than 10 percent, and simultaneously has lower alloy cost, but the Si content in the components is 0.8-2.0 percent, and the surface quality of the produced steel plate is poor, so that the subsequent processing and use are influenced; the patent document with the publication number of CN104532126B proposes a low yield ratio ultrahigh strength hot rolled Q & P steel and a manufacturing method thereof, wherein the tensile strength of the steel plate can reach more than 1300MPa, the yield ratio is lower than 0.50, the structure of the steel plate consists of ferrite, martensite and residual austenite, the steel plate has good strong plastic matching, the Si content in the steel plate is 1.0-2.0%, the surface quality of the steel plate is poor, and meanwhile, the steel contains 0.5% -1.0% of AL, and the smelting difficulty is higher; patent document with publication number CN105177415a proposes an ultra-high strength hot rolled Q & P steel and a method for producing the same, wherein C:0.14-0.45%, si:0.12-2.0%, mn1.0-5.0%, S less than or equal to 0.010%, P less than or equal to 0.015%, H less than or equal to 40ppm, al:0.02-1.5%, nb: and 0.01-0.08%, the cast blank is heated, hot rolled and cooled to obtain a martensite and retained austenite structure, the tensile strength of the steel plate is 1220-1520MPa, the elongation is 14.5-21.2%, and the steel plate has high strength-plastic product, but the steel plate has high Si, mn and Al element contents, so that the surface quality of the steel plate is deteriorated, and the smelting difficulty is improved.
The prior art adopts a hot rolling method to produce high-strength Q & P steel, but the components contain higher Si element, so that the surface quality of the steel plate is deteriorated, the application range of the steel plate is limited, and meanwhile, the components contain higher AL, mn and other elements, so that the smelting difficulty is improved. In view of the above, development of hot rolled pickled surface high strength Q & P steels that are easy to produce is imperative.
Disclosure of Invention
The invention provides 800MPa hot-rolled pickled Q & P steel and a production method thereof, aiming at providing a steel plate with higher plasticity and good surface quality on the premise of higher strength.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
the hot-rolled and pickled Q & P steel of 800MPa grade comprises the following chemical components in percentage by weight: 0.14 to 0.16 percent of C, less than or equal to 0.10 percent of Si, 1.40 to 1.60 percent of Mn, 0.045 to 0.065 percent of P, less than or equal to 0.005 percent of S, 0.02 to 0.05 percent of Al, 0.02 to 0.04 percent of Nb, 0.015 to 0.035 percent of V, 0.15 to 0.30 percent of Mo, less than or equal to 0.006 percent of N, and the balance of Fe and unavoidable impurities.
The steel plate structure consists of ferrite, martensite and residual austenite, wherein the ferrite volume fraction is 13-17%, the martensite volume fraction is 69-76%, and the residual austenite volume fraction is 11-14%.
The tensile strength of the steel plate is 800-880 MPa, the yield strength is 500-580 MPa, and the elongation is more than or equal to 30.0%.
The thickness of the finished steel plate is 2.0-6.0mm.
The surface of the steel plate is an acid-washing surface, the defects of scale stripes, chromatic aberration, cracks and the like are avoided, and the surface roughness Ra of the steel plate is 0.8-1.5 mu m.
The steel plate has the main functions as follows:
c: carbon is a guarantee of the strength of the steel plate, and meanwhile, after coiling, C in martensite diffuses into residual austenite, so that the stability of the austenite is improved, the percentage content of the residual austenite is increased, and the plasticity of the steel plate is improved. The content of C is too high, the content of ferrite generated in the air cooling process in the structure is insufficient, the strength of the steel plate is too high, and the elongation is low; the content of C is too low, the content of formed martensite is too low, the stability of residual austenite is poor, and the strength and plasticity of the steel plate are easy to be reduced. The optimal range of C in the invention is 0.14% -0.16%.
Si: silicon can expand the alpha+gamma region of the Fe-C phase diagram, is beneficial to promoting the transformation from austenite to ferrite in the air cooling process, and ensures that a certain content of ferrite is obtained in the steel plate structure. Meanwhile, si can inhibit cementite precipitation in the coiling air cooling process, so that the distribution of carbon elements from martensite to retained austenite is ensured, and the stability of austenite is improved. At present, a large amount of Si element is added into most Q & P steel, but the larger Si content can greatly deteriorate the surface quality of the steel plate, and the production and the use are affected. The steel plate provided by the invention adopts a low Si component design, and the Si content is less than or equal to 0.10%.
Mn: manganese is an austenite stabilizing element in the invention, obviously improves the hardenability of steel, plays roles of solid solution strengthening and grain refinement, and can obviously delay pearlite transformation and bainite transformation. However, too high Mn content delays ferrite precipitation and tends to give a steel sheet a band structure. Thus, the Mn content is selected to be 1.40% -1.6% in the present invention.
P: phosphorus plays two main roles in the invention, namely, the generation of cementite is inhibited, and the stability of austenite is improved; secondly, the size of the martensite islands is reduced and the martensite islands are uniformly distributed. The content of the P element cannot be too high, grain boundary segregation is easy to occur due to the too high content, the toughness of the steel plate is severely reduced, and the C, nb element in the composition can effectively reduce the grain boundary segregation of the P element. The phosphorus content in the invention is 0.045% -0.065%.
S: sulfur is an impurity element in the present invention, sulfide inclusions such as MnS are easily formed in steel to become a crack source, and workability is deteriorated, so that the lower the content is, the better the content is, but the lower the content is, the higher the smelting cost is, and the sulfur content is not more than 0.005% in the present invention.
Al: aluminum plays a role in the nitrogen fixation deoxidization in the present invention, but too much aluminum causes a large amount of aluminum-based inclusions. The range of Al in the invention is 0.02% -0.05%.
Nb, V: nb and V mainly play roles in strengthening fine crystals, precipitation strengthening and the like in steel. According to the invention, the nano-scale fine carbonitride is dispersed and separated out, so that the original austenite grain boundary can be effectively pinned, each phase structure in the steel plate is further refined, and the comprehensive performances such as toughness and the like are improved. The Nb content in the invention is 0.020-0.040%, and the V content is 0.015-0.035%.
Mo: molybdenum is a medium-strength carbide forming element, and can improve the strength and toughness of the steel plate; mo can obviously improve the stability of residual austenite after coiling, so that certain residual austenite exists in a final structure, and the steel plate reaches the expected mechanical property index. The Mo content in the invention is 0.15-0.30%.
N: the lower the N content, the better, but too low results in difficult production and increased cost, so the N content in the invention is less than or equal to 0.006%.
A production method of 800 MPa-grade hot-rolled pickled Q & P steel comprises the following method steps:
1) The heating process comprises the following steps: heating a casting blank with the thickness of 150-230 mm to 1210-1230 ℃, and preserving heat for 1-2 hours to ensure that alloy elements of the casting blank are uniformly distributed and have smaller original austenite grain size;
2) Rolling and cooling processes: adopting two-stage controlled rolling, wherein the finish rolling temperature is 780-800 ℃; after finishing rolling, adopting a cooling mode of air cooling and ultra-fast cooling: air-cooling to A r3 Continuously air-cooling for 4-6s after the temperature is reached, then performing second-stage ultra-fast cooling, wherein the cooling speed is more than or equal to 100 ℃/s, cooling the steel plate to 280-330 ℃, and then coiling and air-cooling to room temperature;
3) The acid washing process comprises the following steps: the steel plate is cooled to room temperature and then is pickled, the elongation percentage of the pickled and straightened steel plate is 0.5 to 0.8 percent, the steel plate passing speed is 40 to 60m/min, the pickling solution is hydrochloric acid, the concentration is 140 to 180g/l, the pickling process is acid pickling with tension, the tension is 10 to 13kN, and the pickling temperature is 80 to 85 ℃.
According to the invention, the steel plate adopts a low Si component design, so that the surface quality of the steel plate is improved, favorable conditions are created for the subsequent pickling process, meanwhile, the steel plate can be applied to automobile parts with higher requirements on the surface quality, and the risk of cementite precipitation in stages of coiling and matching caused by low Si is eliminated by the elements P, mn and Mo; nb and V elements are added into the structure in a composite way, so that the structure of the steel plate is thinned, and the delayed fracture resistance, toughness and the like of the steel plate are improved; the steel plate hot rolling process adopts low-temperature rolling, which is favorable for refining the structure; the cooling mode adopts a two-section cooling system of air cooling and ultra-fast cooling, and ferrite with a certain content is generated in a tissue in the air cooling stage, so that the aim of improving the plasticity of the steel plate is fulfilled; meanwhile, reasonable technological system parameters are adopted in the pickling stage of the steel plate, so that the mechanical properties of the steel plate are ensured, and meanwhile, the steel plate is enabled to obtain excellent surface quality.
Compared with the prior art, the invention has the beneficial effects that:
1) The invention adopts the design of low Si component, the Si content is less than or equal to 0.10 percent and is far lower than the percentage content of more than 1.0 percent in the traditional process, the surface quality of the steel plate can be improved, the surface roughness Ra of the steel plate after pickling is 0.8-1.5 mu m, and the invention is suitable for the use requirements of automobile parts under the existing process conditions;
2) The invention adopts the cooling technology of air cooling and ultra-fast cooling to obtain the three-phase structure of ferrite, martensite and residual austenite, so that the strength of the steel plate reaches more than 800MPa, and the elongation is more than or equal to 30 percent.
Drawings
FIG. 1 shows the microstructure of a steel sheet according to example 2 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Invention of the inventionExamples are as follows: heating a continuous casting billet with the thickness of 150-230 mm to 1210-1230 ℃, preserving heat for 1-2 hours, rolling, finishing the rolling at 780-800 ℃, adopting a cooling mode of air cooling and ultra-fast cooling after finishing, and air cooling to A r3 And (3) continuing air cooling for 4-6s after the temperature is reached, then performing second-stage ultra-fast cooling, wherein the cooling speed is more than or equal to 100 ℃/s, cooling the steel plate to 280-330 ℃, and then coiling and air cooling to room temperature. The steel plate is cooled to room temperature and then is pickled, the elongation percentage of the acid-pickling withdrawal and straightening is 0.5-0.8%, the concentration of the pickling solution is 140-180g/l, the steel plate passing speed is 40-60m/min, the steel plate is pickled with tension in the pickling process, the tension is 10-13KN, the pickling temperature is 80-85 ℃, and the thickness of the finished steel plate is 2.0-6.0mm.
The specific compositions, temperature regimes, pickling parameters and structure and properties of the steel plates of the 6 examples of the invention are shown in tables 1-4.
The microstructure of the steel plate of example 4 is shown in FIG. 1. TABLE 1 chemical composition (wt.%)
TABLE 2 temperature regime of the examples of the invention
TABLE 3 Pickling schedule of examples of the invention
TABLE 4 tissue and mechanical Property parameters of the examples of the invention
Claims (8)
1. The 800MPa hot-rolled pickled Q & P steel is characterized in that the steel comprises the following chemical components in percentage by weight: 0.14 to 0.16 percent of C, less than or equal to 0.10 percent of Si, 1.40 to 1.60 percent of Mn, 0.045 to 0.065 percent of P, less than or equal to 0.005 percent of S, 0.02 to 0.05 percent of Al, 0.02 to 0.04 percent of Nb, 0.015 to 0.035 percent of V, 0.15 to 0.30 percent of Mo, less than or equal to 0.006 percent of N, and the balance of Fe and unavoidable impurities.
2. An 800 MPa-grade hot-rolled pickled Q & P steel according to claim 1, characterised in that the steel sheet structure consists of ferrite, martensite and retained austenite, wherein the ferrite volume fraction is 13-17%, the martensite volume fraction is 69-76% and the retained austenite volume fraction is 11-14%.
3. The 800 MPa-grade hot-rolled pickled Q & P steel according to claim 1, wherein the tensile strength of the steel sheet is 800-880 MPa, the yield strength is 500-580 MPa, and the elongation is not less than 30.0%.
4. An 800 MPa-grade hot-rolled pickled Q & P steel according to claim 1, characterised in that the finished steel sheet has a thickness of 2.0-6.0mm.
5. An 800 MPa-grade hot-rolled pickled Q & P steel according to claim 1, characterised in that the steel sheet has a surface roughness Ra of 0.8-1.5 μm.
6. A method for producing 800 MPa-grade hot-rolled pickled Q & P steel according to claims 1-5, characterized by the following method steps:
1) The heating process comprises the following steps: heating the casting blank to 1210-1230 ℃, and preserving heat for 1-2 hours;
2) Rolling and cooling processes: adopting two-stage controlled rolling, wherein the finish rolling temperature is 780-800 ℃; after finishing rolling, adopting a cooling mode of air cooling and ultra-fast cooling: empty spaceCooled to A r3 Continuously air-cooling for 4-6s after the temperature is reached, then performing second-stage ultra-fast cooling, wherein the cooling speed is more than or equal to 100 ℃/s, cooling the steel plate to 280-330 ℃, and then coiling and air-cooling to room temperature;
3) The acid washing process comprises the following steps: the steel plate is cooled to room temperature and then is pickled, the elongation percentage of the pickled and straightened steel plate is 0.5-0.8%, the steel plate passing speed is 40-60m/min, the pickling process is acid pickling with tension, the tension is 10-13kN, and the pickling temperature is 80-85 ℃.
7. The method for producing 800 MPa-grade hot-rolled pickled Q & P steel according to claim 6, wherein the thickness of the cast slab in step 1) is 150 to 230mm.
8. The method for producing 800 MPa-grade hot-rolled pickled Q & P steel according to claim 6, wherein the pickling solution in step 3) is hydrochloric acid, and the concentration is 140-180 g/l.
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| CN108486482A (en) * | 2018-06-14 | 2018-09-04 | 鞍钢股份有限公司 | High-yield-strength hot-rolled pickled steel plate with excellent comprehensive performance and production method thereof |
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| CN114058968A (en) * | 2021-11-19 | 2022-02-18 | 鞍钢股份有限公司 | High-plasticity hot forming steel with oxidation resistance for automobile and hot forming process |
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| CN108486482A (en) * | 2018-06-14 | 2018-09-04 | 鞍钢股份有限公司 | High-yield-strength hot-rolled pickled steel plate with excellent comprehensive performance and production method thereof |
| CN110093564A (en) * | 2019-05-06 | 2019-08-06 | 东北大学 | A kind of 1180MPa grade super strength low cost cold rolling quenching partition steel and its manufacturing method |
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| CN114058968A (en) * | 2021-11-19 | 2022-02-18 | 鞍钢股份有限公司 | High-plasticity hot forming steel with oxidation resistance for automobile and hot forming process |
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