CN114717478A - Light high-strength steel and production method thereof - Google Patents
Light high-strength steel and production method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 121
- 239000010959 steel Substances 0.000 title claims abstract description 121
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 36
- 238000005096 rolling process Methods 0.000 claims abstract description 55
- 238000000137 annealing Methods 0.000 claims abstract description 31
- 238000005098 hot rolling Methods 0.000 claims abstract description 24
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 23
- 230000002441 reversible effect Effects 0.000 claims abstract description 21
- 230000009466 transformation Effects 0.000 claims abstract description 21
- 239000002253 acid Substances 0.000 claims abstract description 19
- 238000003723 Smelting Methods 0.000 claims abstract description 16
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 16
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 15
- 239000000956 alloy Substances 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 12
- 239000000126 substance Substances 0.000 claims abstract description 12
- 229910052742 iron Inorganic materials 0.000 claims abstract description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 27
- 229910001566 austenite Inorganic materials 0.000 claims description 25
- 229910000859 α-Fe Inorganic materials 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 12
- 239000012535 impurity Substances 0.000 claims description 12
- 229910000734 martensite Inorganic materials 0.000 claims description 12
- 238000004321 preservation Methods 0.000 claims description 12
- 230000009467 reduction Effects 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 10
- 238000005097 cold rolling Methods 0.000 claims description 7
- 238000005336 cracking Methods 0.000 claims description 5
- 230000000717 retained effect Effects 0.000 claims description 5
- 230000007704 transition Effects 0.000 claims description 5
- 238000005520 cutting process Methods 0.000 claims description 4
- 239000011572 manganese Substances 0.000 description 28
- 230000002829 reductive effect Effects 0.000 description 11
- 239000000203 mixture Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 5
- 230000008569 process Effects 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910000617 Mangalloy Inorganic materials 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 239000010970 precious metal Substances 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 229910000794 TRIP steel Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- -1 manganese-aluminum Chemical compound 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- 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
- 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
- C21D8/0273—Final recrystallisation annealing
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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
-
- 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
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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
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Materials Engineering (AREA)
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- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
The invention discloses light high-strength steel and a production method thereof, belonging to the technical field of metallurgical production processes. Provides the light high-strength steel with relatively low production cost and relatively good processing performance and the production method thereof. The light high-strength steel is a hot-rolled steel plate comprising the following components in parts by weight: 0.23% -0.28%, Si: 0.35-0.65%, Mn: 5.5 to 6.8 percent of the total weight of the alloy, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, Als: 3.0-4.0% of the rest elements are Fe and inevitable impuritiesThe production method at least comprises the steps of molten steel smelting, hot rolling forming, reverse phase transformation annealing and acid rolling, wherein during molten steel smelting, the content of C is controlled to be 0.24-0.27%, the content of Si is controlled to be 0.40-0.50%, the content of Mn is controlled to be 5.7-6.3%, the content of Al is controlled to be 3.3-3.7%, Mn and Al elements in the light high-strength steel after reverse phase transformation annealing act together and then exist in a kappa-carbide form, wherein the chemical formula of the kappa-carbide is (Fe, Mn)3AlC。
Description
Technical Field
The invention relates to light high-strength steel, and belongs to the technical field of metallurgical production processes. The invention also relates to a production method for the light high-strength steel.
Background
In the production process of automobiles and other industries, some structural steel parts with certain requirements on light weight are often needed, but the strength of the light weight steel parts cannot ensure the rigidity of the structure, so that the density of high-strength steel is needed to be reduced to meet the requirements of the light weight structural parts. The prior art generally meets the requirements of the developing industry and manufacturing industry by changing the types and amounts of components in steel to obtain the desired low density steel. Among them, aluminum is added to high manganese steel, and light Fe-Mn-Al-C steel having low density, good ductility, corrosion resistance, etc. can be used because aluminum has low density, good ductility, and easily formed oxide film on the surface. And by adjusting the addition amount of the manganese-aluminum metal, the material with good mechanical properties can be obtained, so that the density can be reduced, and meanwhile, the better structure property and mechanical properties can be maintained. However, there is no fixed range for adjusting various components in the material, and it is difficult to determine the composition range of high performance value, and on the other hand, the performance of the steel depends not only on the composition of the material, but also on the preparation process of the steel, therefore, how to obtain a suitable material composition range and adopt a reasonable preparation process for the material in the composition range is an important issue to be researched.
The invention with publication number CN 111926264A discloses a low-density steel and a manufacturing method thereof, wherein the low-density steel comprises the following chemical components in percentage by weight: 0.8 to 1.6 percent of C, 6.0 to 9.5 percent of Al, the sum of Mn + Nb + V + Mo + Ti is less than or equal to 8 percent, and the balance of Fe and inevitable impurity elements. Heating the hot rolled steel to a temperature above Ac1 and below the critical temperature point Ac3 within a range of 20-130 ℃, and preserving heat for 1-60 min; cooling to 0-50 deg.C below the critical temperature point Ac1, cooling at 0.1-200 deg.C/h, and cooling to room temperature. The technology of the application has the defects that the welding performance of the material with overhigh C content is poor, the rolling process is fuzzy and has no referential property, the content of noble metal is high (Mn + Nb + V + Mo + Ti is less than or equal to 8%), the alloy cost is high, and the like.
The invention with publication number CN 110438315A discloses a heat treatment method for improving the mechanical property of TRIP steel in Fe-Mn-Al-C series, which comprises the following chemical components in percentage by weight: 0.1-0.2% of C, 12-15% of Mn, 2-3% of Al, and the balance of Fe and inevitable impurities. Heating the steel ingot to 1200-1230 ℃, and forging the steel ingot into a steel billet after heat preservation for 2-2.5 hours; and (3) placing the forged blank into a heating furnace, preserving heat for 2-2.5h at the temperature of 1200-1250 ℃, then starting rolling, wherein the initial rolling temperature is 1150-1200 ℃, the final rolling temperature is 850-900 ℃, quenching is carried out at the cooling speed of not less than 100 ℃/h to 590-750 ℃, preserving heat for 1-1.5h, then water quenching is carried out until the tempering temperature of the workpiece at room temperature is 200-220 ℃, preserving heat for 30-50min, and then air cooling is carried out to the room temperature. The alloy cost is increased due to the fact that the alloy contains the precious alloy Nb and relatively more Cr, the alloy is rapidly cooled to 590-750 ℃ after hot rolling, the post-heat-preservation re-quenching process is complex, and the implementation difficulty is high.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the invention provides the light high-strength steel with relatively low production cost and relatively good processing performance, and the invention also provides a production method for the light high-strength steel.
The technical scheme adopted for solving the technical problems is as follows: a light weight high strength steel is a hot rolled steel plate which comprises the following components in parts by weight,
the components in parts by weight are as follows: 0.23% -0.28%, Si: 0.35-0.65%, Mn: 5.5 to 6.8 percent of the total weight of the alloy, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, Als: 3.0 to 4.0 percent of the rest elements are Fe and inevitable impurities,
the yield strength of the light high-strength steel after hot rolling is 520-570 MPa, the tensile strength is 700-760 MPa, and the elongation A is5027.0 to 33.0%; the structure of the steel plate consists of 16 to 23 percent of strip delta ferrite, 40 to 45 percent of ferrite, 19 to 39 percent of lath martensite and 7 to 13 percent of residual austenite.
Further, the components in parts by weight are as follows: 0.24 to 0.27%, Si: 0.40 to 0.50%, Mn: 5.7-6.3%, Al: 3.3 to 3.7 percent of the total weight of the alloy, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S, and the balance of Fe and inevitable impurities.
The production method for the light high-strength steel at least comprises the steps of molten steel smelting, hot rolling forming, reverse phase transformation annealing and acid rolling,
wherein, during the smelting of molten steel, the content of C is controlled to be between 0.24 and 0.27 percent, the content of Si is controlled to be between 0.40 and 0.50 percent, the content of Mn is controlled to be between 5.7 and 6.3 percent, the content of Al is controlled to be between 3.3 and 3.7 percent,
mn and Al elements in the light high-strength steel after reverse phase transformation annealing act together and then exist in a kappa-carbide form,
wherein the chemical formula of the kappa-carbide is (Fe, Mn)3AlC。
Further, the hot rolling forming comprises at least five-pass rough rolling and at least seven-pass finish rolling, and then the steel is coiled and formed under the heat preservation condition of 630-690 ℃, and cooled after heat preservation for at least 4 hours.
The preferable mode of the scheme is that before rough rolling, the plate blank is heated to 1230 +/-20 ℃ and is subjected to heat preservation for 4 hours, then the iron scale is removed, and then the rough rolling is carried out, wherein the reduction rate of each pass is more than or equal to 15% during the rough rolling.
Furthermore, the initial rolling temperature in the finish rolling is more than or equal to 1030 ℃, and the final rolling temperature after 7-pass finish rolling is 880-940 ℃.
The preferable mode of the scheme is that during reverse phase transition annealing, the band steel is slowly heated to 770-810 ℃ by using a hood-type annealing furnace at the speed of 3-8 ℃/min, and is cooled to room temperature along with the furnace after heat preservation for 3-6 hours.
Furthermore, during acid rolling, the surface oxide of the strip steel is cleaned by acid liquor and then subjected to edge cutting treatment, the reduction rate of each pass of cold rolling is controlled within the range of 5-12%, and edge cracking and even strip breakage accidents in the rolling process due to rapid transformation of retained austenite into martensite caused by severe plastic deformation are avoided.
The invention has the beneficial effects that: the application comprises the following components in parts by weight: 0.23% -0.28%, Si: 0.35-0.65%, Mn: 5.5 to 6.8 percent of the total weight of the alloy, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, Als: 3.0-4.0 percent of hot rolled steel plate with the rest elements of Fe and inevitable impurities, then adopting the steps of molten steel smelting, hot rolling forming, reverse phase transformation annealing and acid rolling, strictly controlling the content of C to be 0.24-0.27 percent in the production process, controlling the content of Si to be 0.40-0.50 percent, controlling the content of Mn to be 5.7-6.3 percent, controlling the content of Al to be 3.3-3.7 percent, and enabling Mn and Al elements in the light high-strength steel after the reverse phase transformation annealing to jointly act to exist in a kappa-carbide form, thereby obtaining the hot rolled steel plate with the yield strength of 520-570 MPa, the tensile strength of 700-760 MPa and the elongation A of A5027.0 to 33.0%; the structure of the steel consists of 16 to 23 percent of strip delta ferrite, 40 to 45 percent of ferrite, 19 to 39 percent of lath martensite and 7 to 13 percent of residual austenite. Therefore, the application does not contain precious metals, so that the production cost can be greatly reduced; meanwhile, the manufacturing of the light-weight high-strength steel only comprises the steps of molten steel smelting, hot rolling forming, reverse phase transformation annealing and acid rolling, so that the production difficulty can be effectively reduced, and the processing performance of the finished light-weight high-strength steel can be effectively improved through the control of internal structure.
Drawings
FIG. 1 is a metallographic photograph of a strip steel after hood-type annealing, which is referred to the light high-strength steel of the present invention;
FIG. 2 is a scanning photograph of the strip steel after the cover annealing, which is related to the light high-strength steel of the present invention;
FIG. 3 is a diagram of the residual austenite measuring distribution of the steel strip after the cover annealing, which is related to the light high-strength steel of the invention.
Detailed Description
In order to solve the technical problems in the prior art, the invention provides the light high-strength steel with relatively low production cost and relatively good processability, and the production method for the light high-strength steel. The light high-strength steel is a hot-rolled steel plate comprising the following components in parts by weight: 0.23% -0.28%, Si: 0.35-0.65%, Mn: 5.5 to 6.8 percent of the total weight of the alloy, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, Als: 3.0-4.0% of the balance of Fe and inevitable impurities, wherein the yield strength of the light high-strength steel after hot rolling is 520-570 MPa, the tensile strength is 700-760 MPa, and the elongation A is5027.0 to 33.0%; the structure of the steel plate consists of 16-23% of strip delta ferrite, 40-45% of ferrite, 19-39% of lath martensite and 7-13% of residual austenite. The production method at least comprises the steps of molten steel smelting, hot rolling forming, reverse phase transformation annealing and acid rolling, wherein during molten steel smelting, the content of C is controlled to be 0.24-0.27%, the content of Si is controlled to be 0.40-0.50%, the content of Mn is controlled to be 5.7-6.3%, the content of Al is controlled to be 3.3-3.7%, Mn and Al elements in the light high-strength steel after reverse phase transformation annealing are acted together and then exist in a kappa-carbide form, wherein the chemical formula of the kappa-carbide is (Fe, Mn)3And (4) AlC. The application provides a composition which comprises the following components in parts by weight: 0.23% -0.28%, Si: 0.35-0.65%, Mn: 5.5-6.8%, P is less than or equal to 0.020%, S is less than or equal to 0.010%, Als: 3.0-4.0 percent of hot rolled steel plate with the rest elements of Fe and inevitable impurities, then adopting the steps of molten steel smelting, hot rolling forming, reverse phase transformation annealing and acid rolling, strictly controlling the content of C to be 0.24-0.27 percent in the production process, controlling the content of Si to be 0.40-0.50 percent, controlling the content of Mn to be 5.7-6.3 percent, controlling the content of Al to be 3.3-3.7 percent, and enabling Mn and Al elements in the light high-strength steel after the reverse phase transformation annealing to jointly act to exist in a kappa-carbide form, thereby obtaining the hot rolled steel plate with the yield strength of 520-570 MPa, the tensile strength of 700-760 MPa and the elongation A of A5027.0 to 33.0%; the tissue content is 16% -23%The light-weight high-strength steel is composed of strip delta ferrite, 40% -45% of ferrite, 19% -39% of lath martensite and 7% -13% of residual austenite. Therefore, the application does not contain precious metals, so that the production cost can be greatly reduced; meanwhile, the manufacturing of the light-weight high-strength steel only comprises the steps of molten steel smelting, hot rolling forming, reverse phase transformation annealing and acid rolling, so that the production difficulty can be effectively reduced, and the processing performance of the finished light-weight high-strength steel can be effectively improved through the control of internal structure.
In the above embodiment, the preferable content of the components in parts by weight is C: 0.24 to 0.27%, Si: 0.40 to 0.50%, Mn: 5.7-6.3%, Al: 3.3 to 3.7 percent of the total weight of the alloy, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S, and the balance of Fe and inevitable impurities. Correspondingly, in the production and manufacturing process, the mode of each step is selected firstly, the hot rolling forming comprises at least five-pass rough rolling and at least seven-pass finish rolling, and then the hot rolling forming is coiled and formed under the heat preservation condition of 630-690 ℃, and the hot rolling forming is cooled after the heat preservation for at least 4 hours. Before rough rolling, the plate blank is heated to 1230 +/-20 ℃ and is kept warm for 4 hours, then the iron scale is removed, and the rough rolling is carried out, wherein the reduction rate of each pass is more than or equal to 15 percent during the rough rolling. The initial rolling temperature during finish rolling is more than or equal to 1030 ℃, and the final rolling temperature after finishing finish rolling of 7 passes is 880-940 ℃. And in the reverse phase transition annealing, the band steel is slowly heated to 770-810 ℃ by using a hood-type annealing furnace at the speed of 3-8 ℃/min, and is cooled to room temperature along with the furnace after heat preservation for 3-6 hours. During acid rolling, the surface oxide of the strip steel is cleaned by acid liquor and then subjected to edge cutting treatment, the reduction rate of each pass of cold rolling is controlled within the range of 5-12%, and edge cracking and even strip breakage accidents in the rolling process caused by rapid transformation of retained austenite into martensite due to severe plastic deformation are avoided.
In summary, the lightweight high-strength steel manufactured by the technical scheme provided by the application reduces the density of steel by adding the lightweight element C, Al and the like, so that the weight is reduced on the basis of ensuring the strength and plasticity of the product, and the weight of the steel for the automobile is promoted to be reduced. Meanwhile, Al is used for inhibiting the precipitation of cementite, so that carbon elements are enriched in the residual austenite, and the hardenability is improved. The addition of an amount of Mn (about 6%) element enlarges the adverse effects of narrowing the austenite phase region in the austenite region and the Al added band. The transformation from martensite to austenite is realized through reverse phase transformation annealing, and the workability of the product is improved. The strip steel is rolled to the specified thickness by the reversible cold rolling mill set, so that uniform raw materials with good plate shape/thickness precision are prepared for subsequent heat treatment, and technical support is provided for developing high-strength low-density automobile steel.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
As shown in fig. 1, 2 and 3, the present invention aims to provide a low-cost hot-rolled light-weight high-strength steel sheet.
The technical scheme of the invention is as follows: a hot-rolled light high-strength steel plate with low cost and excellent mechanical property is produced by using a hot rolling unit. The chemical composition range is as follows: c: 0.23% -0.28%, Si: 0.35-0.65%, Mn: 5.5 to 6.8 percent of the total weight of the alloy, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, Als: 3.0-4.0% of the rest elements are Fe and inevitable impurities.
In the preferable low-cost hot-rolled light high-strength steel plate, the chemical components are as follows by weight percent: c: 0.24 to 0.27%, Si: 0.40 to 0.50%, Mn: 5.7-6.3%, Al: 3.3 to 3.7 percent of the total weight of the alloy, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S, and the balance of Fe and inevitable impurities.
Wherein the yield strength of the light high-strength steel plate before acid rolling is 520-570 MPa, the tensile strength is 700-760 MPa, and the elongation A is5027.0 to 33.0%; the structure consists of strip-shaped delta ferrite (16% -23%) + ferrite (40% -45%) + lath martensite (19% -39%) + retained austenite (7% -13%).
The production steps of the light high-strength steel plate comprise:
(a) smelting: smelting according to chemical components of the low-cost hot-rolled light high-strength steel plate, and casting into a plate blank;
(b) hot rolling: heating the plate blank to 1230 +/-20 ℃, preserving the temperature for 4 hours, removing the iron scale, and carrying out 5-pass rough rolling, wherein the reduction rate of each pass is more than or equal to 15%. The initial rolling temperature of finish rolling is more than or equal to 1030 ℃, the final rolling temperature of 7-pass finish rolling is 880-940 ℃, coiling is carried out after controlled cooling, the coiling temperature is 630-690 ℃, and cooling is carried out after heat preservation is carried out for 4 hours.
(c) Reverse phase transition annealing: and slowly heating the strip steel to 770-810 ℃ by using a hood-type annealing furnace at the speed of 3-8 ℃/min, preserving heat for 3-6 hours, and cooling the strip steel to room temperature along with the furnace.
(d) Acid rolling: the surface oxide of the strip steel is cleaned by acid liquor and then subjected to edge cutting treatment, the reduction rate of each cold rolling pass is controlled within the range of 5-12%, and edge cracking and even strip breakage accidents in the rolling process caused by rapid transformation of retained austenite into martensite due to severe plastic deformation are avoided.
The alloy elements have the following functions in low-cost hot rolling of the light high-strength steel plate:
carbon: c is an important austenite element in steel, and can stabilize the austenite structure and also promote the reduction of density. Meanwhile, C can react with microalloy element-shaped carbide in steel and Mn and Al to generate kappa-carbide ((Fe, Mn)3AlC) and the two act together to produce precipitation strengthening and improve the strength of the steel. The C content is too low, so that the austenite structure in the steel is unstable, the precipitation amount of carbides in the steel is reduced, and the strength and the toughness of the low-density steel are reduced. However, since too high a C content promotes the formation of coarse kappa carbides at austenite grain boundaries and deteriorates the elongation of the low-density steel, the C content in the present invention is 0.23 to 0.28%, preferably 0.24 to 0.27%.
Silicon: si can be dissolved in ferrite and austenite in a solid solution mode to improve the strength of the steel, the effect of the Si is second to C, P, and the Si is stronger than Mn, Cr, Ti, Ni and other elements; si can also inhibit carbide in ferrite from being precipitated, so that solid-solution C atoms are fully enriched in austenite, and the Si content with excessively low stability is improved, and residual austenite is difficult to obtain at room temperature. However, when the content of Si is too high, the surface iron scale formed by Si in the heating furnace is difficult to remove, so that the dephosphorization difficulty is increased; meanwhile, SiO2 is easily enriched on the surface during annealing, thereby causing surface defects such as plating leakage and the like. Therefore, the Si content of the present invention is 0.35 to 0.65%, preferably 0.40 to 0.50%.
Manganese: mn is an austenitizing element, and the addition of the Mn element can expand an austenite phase region, improve the austenite content, improve the fault energy of steel, inhibit martensite phase transformation, generate dense twin crystals in the deformation process and effectively improve the elongation of the steel. Therefore, the Mn content is 5.5 to 6.8%, preferably 5.7 to 6.3% in the present invention.
Aluminum: the density of Al is 2.7g/cm3Much lower than 7.85g/cm3The density of the Fe can be obviously reduced. The Al content can also obviously improve the heat deformation resistance of the steel, improve the corrosion resistance of the steel and delay dynamic cracking, and the Al can also obviously improve the fault energy of the steel and change the deformation mechanism, so that the medium manganese steel containing the Al can have a certain buffer effect when violent collision occurs. However, considering that Al is a strong ferrite element, too high Al content tends to promote the formation of ferrite phase and to reduce the austenite phase content. Therefore, the Al content in the present invention is 3.0% to 4.0%, preferably 3.3 to 3.7%.
Example one
The present example provides two sets of lightweight high-strength steels, whose chemical compositions are shown in table 1;
table 1 chemical composition (wt.%) of light high strength steel
| Numbering | C | Si | Mn | P | S | Als |
| 1 | 0.252 | 0.43 | 5.93 | 0.010 | 0.005 | 3.52 |
| 2 | 0.261 | 0.47 | 6.12 | 0.008 | 0.003 | 3.37 |
The preparation method of the low-light-weight high-strength steel plate comprises the following specific processes:
A. smelting: preparing a light steel plate blank with chemical components shown in a table 1 through a smelting process;
B. a hot rolling procedure: heating, hot rolling and hot coiling the plate blank, wherein the specific hot rolling process parameters are shown in a table 2;
TABLE 2 Main Hot Rolling Process parameters of light high Strength Steel
| Numbering | Heating temperature of | Final Rolling temperature/. degree.C | Coiling temperature/. degree.C | Thickness/mm of hot rolled product |
| 1 | 1062 | 903 | 646 | 3.9 |
| 2 | 1058 | 917 | 673 | 3.5 |
C. Reverse phase transition annealing: the strip steel is slowly heated to a target temperature by using a hood-type annealing furnace, is cooled along with the furnace after being kept warm for a period of time, and the parameters are shown in Table 3
TABLE 3 light high-strength steel Main cover annealing technological parameters
| Numbering | Heating speed/min | Annealing temperature/. degree.C | Incubation time/. degree.C |
| 1 | 5.5 | 783 | 4.5 |
| 2 | 6.5 | 806 | 5.0 |
D. Acid rolling: and cold-rolling the strip steel cleaned by the acid liquor to a specified thickness at a reduction rate of 5-12% of cold rolling per pass. The reduction per pass of the experimental steels is shown in table 4.
TABLE 4 thickness setting for each pass of light high-strength steel
Claims (8)
1. A light high-strength steel is characterized in that: the light high-strength steel is a hot-rolled steel plate comprising the following components in parts by weight,
the components in parts by weight are as follows: 0.23% -0.28%, Si: 0.35-0.65%, Mn: 5.5-6.8%, P is less than or equal to 0.020%, S is less than or equal to 0.010%, Als: 3.0 to 4.0 percent of the rest elements are Fe and inevitable impurities,
the yield strength of the light high-strength steel after hot rolling is 520-570 MPa, the tensile strength is 700-760 MPa, and the elongation rate A is5027.0 to 33.0%; the structure of the steel plate consists of 16-23% of strip delta ferrite, 40-45% of ferrite, 19-39% of lath martensite and 7-13% of residual austenite.
2. A lightweight high-strength steel according to claim 1, characterized in that: the components in parts by weight are as follows: 0.24 to 0.27%, Si: 0.40 to 0.50%, Mn: 5.7-6.3%, Al: 3.3 to 3.7 percent of the total weight of the alloy, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S, and the balance of Fe and inevitable impurities.
3. A production method for the light weight, high strength steel according to claim 1 or 2, characterized by: the production method at least comprises the steps of molten steel smelting, hot rolling forming, reverse phase transformation annealing and acid rolling,
wherein, during the smelting of molten steel, the content of C is controlled to be between 0.24 and 0.27 percent, the content of Si is controlled to be between 0.40 and 0.50 percent, the content of Mn is controlled to be between 5.7 and 6.3 percent, the content of Al is controlled to be between 3.3 and 3.7 percent,
mn and Al elements in the light high-strength steel after reverse phase transformation annealing act together and then exist in a kappa-carbide form,
wherein the chemical formula of the kappa-carbide is (Fe, Mn)3AlC。
4. The production method according to claim 3, characterized in that: the hot rolling forming comprises at least five-pass rough rolling and at least seven-pass finish rolling, and then coiling forming is carried out under the heat preservation condition of 630-690 ℃, heat preservation is carried out for at least 4 hours, and cooling is carried out.
5. The production method according to claim 4, characterized in that: before rough rolling, the plate blank is heated to 1230 +/-20 ℃ and is kept warm for 4 hours, then the iron scale is removed, and the rough rolling is carried out, wherein the reduction rate of each pass is more than or equal to 15 percent during the rough rolling.
6. The production method according to claim 5, characterized in that: the initial rolling temperature during finish rolling is more than or equal to 1030 ℃, and the final rolling temperature after finishing finish rolling of 7 passes is 880-940 ℃.
7. The production method according to claim 3, characterized in that: and during reverse phase transition annealing, slowly heating the strip steel to 770-810 ℃ at the speed of 3-8 ℃/min by using a hood-type annealing furnace, preserving heat for 3-6 hours, and cooling the strip steel to room temperature along with the furnace.
8. The production method according to claim 7, characterized in that: during acid rolling, the surface oxide of the strip steel is cleaned by acid liquor and then subjected to edge cutting treatment, the reduction rate of each pass of cold rolling is controlled within the range of 5-12%, and edge cracking and even strip breakage accidents in the rolling process caused by rapid transformation of retained austenite into martensite due to severe plastic deformation are avoided.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117107168A (en) * | 2023-08-07 | 2023-11-24 | 武汉科技大学 | Low-density steel plate with ultrahigh strength and ductility product and preparation method thereof |
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| JPH0559429A (en) * | 1991-09-03 | 1993-03-09 | Nippon Steel Corp | Production of high strength cold rolled sheet of dual-phase steel excellent in workability |
| CN104928568A (en) * | 2015-06-30 | 2015-09-23 | 宝山钢铁股份有限公司 | Ferrite low-density high-strength steel and manufacturing method thereof |
| CN111575580A (en) * | 2020-05-08 | 2020-08-25 | 钢铁研究总院 | High-strength-toughness and high-strength-ductility automobile steel and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0559429A (en) * | 1991-09-03 | 1993-03-09 | Nippon Steel Corp | Production of high strength cold rolled sheet of dual-phase steel excellent in workability |
| CN104928568A (en) * | 2015-06-30 | 2015-09-23 | 宝山钢铁股份有限公司 | Ferrite low-density high-strength steel and manufacturing method thereof |
| CN111575580A (en) * | 2020-05-08 | 2020-08-25 | 钢铁研究总院 | High-strength-toughness and high-strength-ductility automobile steel and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117107168A (en) * | 2023-08-07 | 2023-11-24 | 武汉科技大学 | Low-density steel plate with ultrahigh strength and ductility product and preparation method thereof |
| CN117107168B (en) * | 2023-08-07 | 2024-05-24 | 武汉科技大学 | Low-density steel plate with ultrahigh strength and ductility product and preparation method thereof |
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