CN117448689A - High-strength plastic accumulation difference thick plate for automobile and preparation method thereof - Google Patents
High-strength plastic accumulation difference thick plate for automobile and preparation method thereof Download PDFInfo
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- CN117448689A CN117448689A CN202311559818.2A CN202311559818A CN117448689A CN 117448689 A CN117448689 A CN 117448689A CN 202311559818 A CN202311559818 A CN 202311559818A CN 117448689 A CN117448689 A CN 117448689A
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- 238000009825 accumulation Methods 0.000 title claims abstract description 68
- 238000002360 preparation method Methods 0.000 title abstract description 14
- 238000010438 heat treatment Methods 0.000 claims abstract description 48
- 238000005096 rolling process Methods 0.000 claims abstract description 46
- 238000010791 quenching Methods 0.000 claims abstract description 26
- 230000000171 quenching effect Effects 0.000 claims abstract description 26
- 238000005097 cold rolling Methods 0.000 claims abstract description 25
- 238000005098 hot rolling Methods 0.000 claims abstract description 17
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 13
- 238000009826 distribution Methods 0.000 claims abstract description 13
- 229910052729 chemical element Inorganic materials 0.000 claims abstract description 9
- 239000012535 impurity Substances 0.000 claims abstract description 9
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 9
- 238000009628 steelmaking Methods 0.000 claims abstract description 9
- 230000007704 transition Effects 0.000 claims description 34
- 238000001816 cooling Methods 0.000 claims description 24
- 238000000034 method Methods 0.000 claims description 19
- 238000003723 Smelting Methods 0.000 claims description 16
- 238000005554 pickling Methods 0.000 claims description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 238000000137 annealing Methods 0.000 claims description 10
- 150000003839 salts Chemical class 0.000 claims description 9
- 229910001566 austenite Inorganic materials 0.000 claims description 8
- 238000005266 casting Methods 0.000 claims description 8
- 238000005242 forging Methods 0.000 claims description 8
- 229910000734 martensite Inorganic materials 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 8
- 230000000717 retained effect Effects 0.000 claims description 2
- 238000004321 preservation Methods 0.000 claims 1
- 238000009776 industrial production Methods 0.000 abstract description 2
- 239000002184 metal Substances 0.000 abstract description 2
- 229910052751 metal Inorganic materials 0.000 abstract description 2
- 238000001514 detection method Methods 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- 229910052717 sulfur Inorganic materials 0.000 description 6
- 230000001603 reducing effect Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 229910000851 Alloy steel Inorganic materials 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
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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
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
-
- 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
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
- C21D2211/008—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
Abstract
The invention relates to a high-strength plastic accumulation difference thick plate for an automobile and a preparation method thereof, belonging to the technical field of rolling. The mass percentages of the chemical elements of the differential plate are as follows: 0.22 to 0.28 percent of C, 1.55 to 1.65 percent of Si, 1.50 to 1.65 percent of Mn, P: less than or equal to 0.002 percent, S: less than or equal to 0.002 percent, N: less than or equal to 0.003 percent, al: less than or equal to 0.04 percent, and the balance of Fe and unavoidable impurities. The preparation method of the high-strength plastic accumulation difference thick plate for the automobile comprises the following steps: (1) steelmaking and blank making; (2) hot rolling; (3) cold rolling; (4) variable thickness rolling; and (5) quenching and distributing heat treatment. The thickness of the thick area of the high-strength plastic accumulation difference thick plate for the automobile prepared by the invention is as follows: 2.0mm and the thickness of the thin area is 1.0mm. The high-strength plastic accumulation difference thick plate for the automobile, which is prepared by the invention, has different thickness areas, and the performances of the different thickness areas are different, so that the bearing capacity of the metal can be exerted to the maximum extent under the condition of uneven load distribution of automobile parts, the structural weight is greatly reduced, the energy is saved, the emission is reduced, the production efficiency is high, the production cost is low, and the mass industrial production is easy to realize.
Description
Technical Field
The invention belongs to the technical field of rolling, and particularly relates to a high-strength plastic accumulation difference thick plate for an automobile and a preparation method thereof.
Background
The cold-rolled differential thick plate is used in the industries of automobile manufacture, shipbuilding, bridges and the like, and has the advantages of saving materials and weight, reducing welding seams, reducing cost, improving efficiency and the like. The thick and thin plate produced by the variable thickness rolling method has thin areas, thick areas and transition areas with different thicknesses. Compared with a laser splice welding plate, the differential thick plate has no welding line, good quality, low production cost and high efficiency, and the length and the shape of the transition area can be designed according to the stress condition of the stamping part in service, so that the differential thick plate has more obvious material saving and weight reducing effects and is valued. The differential plate is applied to manufacturing of light-weight parts of automobiles at home and abroad, and the light-weight parts of automobiles which can be manufactured by the differential plate are a lot, including B columns, anti-collision beams, front longitudinal beams and the like, and the low-alloy steel differential plate is widely applied at present. The differential thick plate is used as steel for automobiles, and has high strength and high plasticity while saving materials and reducing weight, so that the performance requirements of automobiles in the aspects of light weight and collision safety can be well met. At present, the product of strength and elongation of a low alloy steel differential plate applied to automobiles is generally lower than 15000MPa, and the high-strength and elongation differential plate has not been developed and applied yet. Therefore, the development of the high-strength plastic poor thick plate and the preparation method thereof can promote the application process of the high-strength plastic poor thick plate in the light weight of automobiles.
Disclosure of Invention
The invention aims to provide a high-strength and high-plasticity accumulation difference thick plate for an automobile and a preparation method thereof, and mechanical properties of high-strength and high-plasticity accumulation in different thickness areas of the difference thick plate are obtained through combination of variable thickness rolling and quenching distribution heat treatment processes.
The invention relates to a high-strength plastic accumulation difference thick plate for an automobile, which comprises the following chemical elements in percentage by mass: 0.22 to 0.28 percent of C, 1.55 to 1.65 percent of Si, 1.50 to 1.65 percent of Mn, P: less than or equal to 0.002 percent, S: less than or equal to 0.002 percent, N: less than or equal to 0.003 percent, al: less than or equal to 0.04 percent, and the balance of Fe and unavoidable impurities.
The thickness of the thick area of the high-strength plastic accumulation difference thick plate for the automobile is as follows: the thickness of the thin area is 1.0mm and 2.0mm, and the high-strength plastic accumulation difference thick plate for the automobile is provided with a transition area, and the curve of the transition area is in linear leading transition.
The tensile strength of the high-strength plastic accumulation difference thick plate for the automobile is more than 1500MPa, and the plastic accumulation is more than 15000 MPa. Wherein the tensile strength of the thick region is: 1560-1650 MPa, and the yield strength is: 850-1020 MPa, the elongation is 13-16%, and the product of strength and plastic is 21500-25500 MPa; the tensile strength of the thin region is: 1500-1600 MPa, yield strength is: 860-1050 MPa, 10-12% of elongation and 15400-16800 MPa of strength-plastic product.
The microstructure of the thick area and the thin area of the high-strength plastic accumulation difference thick plate for the automobile is mainly as follows: martensite and a small amount of retained austenite.
The invention discloses a preparation method of a high-strength plastic accumulation difference thick plate for an automobile, which comprises the following steps of:
step 1: steelmaking blank making
Smelting in a vacuum smelting furnace of 150kg according to the chemical components of the high-strength and high-plasticity accumulation difference thick plate for the automobile, casting into cast ingots, and forging to obtain billets with the dimensions of 60mm multiplied by 450 mm;
step 2: hot rolling
Placing the billet into a heating furnace for heating, then rolling the billet on a 450mm hot rolling mill, rolling for 6 times, and then air-cooling to obtain a hot rolled plate blank with the thickness of 4.5 mm;
step 3: cold rolling
Pickling the hot-rolled plate blank, cold-rolling to 2.2mm, annealing, and cooling to room temperature along with a furnace;
step 4: variable thickness rolling
Carrying out single-pass variable thickness rolling on the cold-rolled sheet after pickling on a four-roll cold-rolling mill, and obtaining a differential thick plate by dynamically adjusting roll gap rolling in real time;
step 5: quenching and distributing heat treatment
And heating the difference thick plate in a heating furnace, then carrying out a quenching carbon distribution process in a salt bath furnace, and finally rapidly quenching and cooling to room temperature to obtain the high-strength plastic accumulation difference thick plate.
Further, the heating temperature in the step 2 is 1200-1250 ℃, and the temperature is kept for 6 hours.
Further, the annealing temperature in the step 3 is 610-630 ℃, and the temperature is kept for 1 hour.
Further, the difference thick plate thickness area in the step 4 is 2.0mm, the thin area is 1.0mm, and the transition area is provided with a transition area, and the curve of the transition area is a straight line dominant transition.
Further, the heating temperature in the step 5 is 900-950 ℃ and kept for 10-20 min, then the salt bath is quenched to a certain temperature between 250-290 ℃ and kept for 20-300 s for carbon distribution.
The invention has the beneficial effects that: the high-strength plastic accumulation difference thick plate for the automobile has tensile strength of more than 1500MPa, plastic accumulation of more than 15000MPa, and maximum plastic accumulation of 25500MPa, and can be used as a raw material for manufacturing light-weight parts of the automobile. The product prepared by the method has different thickness areas, and the performances of the different thickness areas are different, so that the bearing capacity of the metal can be exerted to the maximum extent under the condition of uneven load distribution of automobile parts, the structure weight is greatly reduced, and the good effects of energy conservation and emission reduction are obtained. The method of the invention utilizes the variable thickness rolling and heat treatment method to obtain the technical route of the high-strength and high-plasticity thick plate, has the advantages of high production efficiency, low production cost and the like, and is easy to realize mass industrial production.
Drawings
FIG. 1 is a schematic view of two longitudinal variable thickness plates, wherein (a) is a schematic view of a laser tailor welded blank and (b) is a schematic view of a rolled differential thickness plate according to the present invention;
FIG. 2 is a schematic view of a high-strength and high-plasticity accumulation difference thick plate for an automobile, which is prepared by the embodiment of the invention;
FIG. 3 is a photograph of a scanning electron microscope of a high-strength, high-plasticity, low-thickness plate for automobile prepared in example 1 of the present invention, wherein (a) is the structure of a thin region (thickness 1.0 mm), and (b) is the structure of a thick region (thickness 2.0 mm);
FIG. 4 is a photograph of a scanning electron microscope of a high-strength, high-plasticity, low-thickness plate for automobile prepared in example 2 of the present invention, wherein (a) is the structure of a thin region (thickness 1.0 mm), and (b) is the structure of a thick region (thickness 2.0 mm);
FIG. 5 is a photograph of a scanning electron microscope of a high-strength, high-plasticity, low-thickness plate for automobile prepared in example 3 of the present invention, wherein (a) is the structure of a thin region (thickness 1.0 mm), and (b) is the structure of a thick region (thickness 2.0 mm);
FIG. 6 is a photograph of a scanning electron microscope of a high-strength, high-plasticity, low-thickness plate for automobile prepared in example 4 of the present invention, wherein (a) is the structure of a thin region (thickness 1.0 mm), and (b) is the structure of a thick region (thickness 2.0 mm);
FIG. 7 is a photograph of a scanning electron microscope of a high-strength, high-plasticity, low-thickness plate for automobile prepared in example 5 of the present invention, wherein (a) is the structure of a thin region (thickness 1.0 mm), and (b) is the structure of a thick region (thickness 2.0 mm);
FIG. 8 is a photograph of a Scanning Electron Microscope (SEM) of a thick plate of high-strength and high-plasticity (high-strength) and low-thickness for automobile, which is prepared in example 6 of the present invention, wherein (a) is the structure of a thin region (thickness 1.0 mm), and (b) is the structure of a thick region (thickness 2.0 mm);
FIG. 9 is an X-ray diffraction chart of the structure of the thin and thick regions of the high-strength and high-plasticity thick plate for automobile prepared in example 6 of the present invention.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by those skilled in the art without making any inventive effort based on the embodiments of the present invention are within the scope of protection of the present invention.
The present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed in breadth and scope in accordance with the appended claims.
FIG. 1 is a schematic view of two longitudinal variable thickness plates, wherein (a) is a schematic view of a laser tailor welded blank and (b) is a schematic view of a rolled differential thickness plate according to the present invention; fig. 2 is a schematic diagram of a high-strength and high-plasticity accumulation difference thick plate for an automobile, which is prepared by the embodiment of the invention.
Example 1
The high-strength plastic accumulation difference thick plate for the automobile comprises the following chemical elements in percentage by mass: 0.25% of C, 1.58% of Si, 1.55% of Mn and P:0.002%, S:0.001%, N:0.003%, al:0.04%, and the balance of Fe and unavoidable impurities.
The preparation method of the high-strength plastic accumulation difference thick plate for the automobile comprises the following steps of:
step 1: steelmaking blank making
Smelting in a vacuum smelting furnace of 150kg according to the chemical components of the high-strength and high-plasticity accumulation difference thick plate for the automobile, casting into cast ingots, and forging to obtain billets with the dimensions of 60mm multiplied by 450 mm;
step 2: hot rolling
Heating the billet in a heating furnace to 1200 ℃, preserving heat for 6 hours, rolling on a 450mm hot rolling mill, rolling for 6 times, and then air cooling to obtain a hot rolled plate blank with the thickness of 4.5 mm;
step 3: cold rolling
Pickling the hot-rolled plate blank, cold-rolling to 2.2mm, annealing at 620 ℃, preserving heat for 1 hour, and cooling to room temperature along with a furnace;
step 4: variable thickness rolling
Carrying out single-pass variable thickness rolling on a four-roller cold rolling mill after pickling the cold-rolled sheet, and obtaining a differential thick plate with a thick area of 2.0mm and a thin area of 1.0mm and a transition area by dynamically adjusting roll gap rolling in real time, wherein the curve of the transition area is in straight line leading type transition;
step 5: quenching and distributing heat treatment
Heating the differential thick plate to an austenitizing temperature of 900 ℃ in a heating furnace, preserving heat for 10min, quenching to 250 ℃ in a salt bath, preserving heat for 300s at the temperature, carrying out a carbon distribution process, and finally rapidly quenching and cooling to room temperature to obtain the high-strength plastic differential thick plate.
The scanning structure photo of the high-strength plastic accumulation difference thick plate for the automobile prepared by the embodiment is shown in figure 3, and the graph shows that most of the structure is lath martensite, and the volume fraction of residual austenite in the thin area and the thick area is 3-6% measured by XRD.
Mechanical property detection is carried out on the high-strength plastic accumulation difference thick plate for the automobile, and the tensile strength of the thick area is measured as follows: 1594MPa, yield strength: 863MPa, elongation of 15.3% and strength-plastic product of 24309 MPa; the tensile strength of the thin region is: 1515MPa, yield strength: 865MPa, elongation of 11.0% and strength-plastic product of 16660 MPa.
Example 2
The high-strength plastic accumulation difference thick plate for the automobile comprises the following chemical elements in percentage by mass: 0.26% of C, 1.62% of Si, 1.60% of Mn and P:0.002%, S:0.001%, N:0.003%, al:0.04%, and the balance of Fe and unavoidable impurities.
The preparation method of the high-strength plastic accumulation difference thick plate for the automobile comprises the following steps of:
step 1: steelmaking blank making
Smelting in a vacuum smelting furnace of 150kg according to the chemical components of the high-strength and high-plasticity accumulation difference thick plate for the automobile, casting into cast ingots, and forging to obtain billets with the dimensions of 60mm multiplied by 450 mm;
step 2: hot rolling
Heating the billet in a heating furnace to 1200 ℃, preserving heat for 6 hours, rolling on a 450mm hot rolling mill, rolling for 6 times, and then air cooling to obtain a hot rolled plate blank with the thickness of 4.5 mm;
step 3: cold rolling
Pickling the hot-rolled plate blank, cold-rolling to 2.2mm, annealing at 620 ℃, preserving heat for 1 hour, and cooling to room temperature along with a furnace;
step 4: carrying out single-pass variable thickness rolling on a four-roll cold rolling mill after pickling a cold-rolled sheet by variable thickness rolling, and obtaining a differential thick plate with a thick area of 2.0mm, a thin area of 1.0mm and a transition area by dynamically adjusting roll gap rolling in real time, wherein the curve of the transition area is in linear leading transition;
step 5: quenching and distributing heat treatment
Heating the differential thick plate to an austenitizing temperature of 900 ℃ in a heating furnace, preserving heat for 10min, quenching to 250 ℃ in a salt bath, preserving heat for 60s at the temperature, carrying out a carbon distribution process, and finally rapidly quenching and cooling to room temperature to obtain the high-strength plastic differential thick plate.
The scanning structure photo of the high-strength plastic accumulation difference thick plate for the automobile prepared by the embodiment is shown in fig. 4, and the graph shows that most of the structure is lath martensite, and the volume fraction of residual austenite in the thin area and the thick area is 3-6% measured by XRD.
Mechanical property detection is carried out on the high-strength plastic accumulation difference thick plate for the automobile, and the tensile strength of a thick area is 1648MPa, the yield strength is 1005MPa, the elongation is 14.8%, and the strong plastic accumulation is 24315 MPa; the tensile strength of the thin region is: 1602MPa, yield strength: 970MPa, elongation of 10.5% and strength-plastic product of 16846 MPa.
Example 3
The high-strength plastic accumulation difference thick plate for the automobile comprises the following chemical elements in percentage by mass: 0.25% of C, 1.58% of Si, 1.55% of Mn and P:0.002%, S:0.001%, N:0.003%, al:0.04%, and the balance of Fe and unavoidable impurities.
The preparation method of the high-strength plastic accumulation difference thick plate for the automobile comprises the following steps of:
step 1: steelmaking blank making
Smelting in a vacuum smelting furnace of 150kg according to the chemical components of the high-strength and high-plasticity accumulation difference thick plate for the automobile, casting into cast ingots, and forging to obtain billets with the dimensions of 60mm multiplied by 450 mm;
step 2: hot rolling
Heating the billet in a heating furnace to 1200 ℃, preserving heat for 6 hours, rolling on a 450mm hot rolling mill, rolling for 6 times, and then air cooling to obtain a hot rolled plate blank with the thickness of 4.5 mm;
step 3: cold rolling
Pickling the hot-rolled plate blank, cold-rolling to 2.2mm, annealing at 620 ℃, preserving heat for 1 hour, and cooling to room temperature along with a furnace;
step 4: carrying out single-pass variable thickness rolling on a four-roll cold rolling mill after pickling a cold-rolled sheet by variable thickness rolling, and obtaining a differential thick plate with a thick area of 2.0mm, a thin area of 1.0mm and a transition area by dynamically adjusting roll gap rolling in real time, wherein the curve of the transition area is in linear leading transition;
step 5: quenching and distributing heat treatment
Heating the differential thick plate to an austenitizing temperature of 900 ℃ in a heating furnace, preserving heat for 10min, quenching to 250 ℃ in a salt bath, preserving heat for 20s at the temperature, carrying out a carbon distribution process, and finally rapidly quenching and cooling to room temperature to obtain the high-strength plastic differential thick plate.
The scanning structure photo of the high-strength plastic accumulation difference thick plate for the automobile prepared by the embodiment is shown in fig. 5, and the graph shows that most of the structure is lath martensite, and the volume fraction of residual austenite in the thin area and the thick area is 3-6% measured by XRD.
Mechanical property detection is carried out on the high-strength plastic accumulation difference thick plate for the automobile, and the tensile strength of a thick area is 1650MPa, the yield strength is 990MPa, the elongation is 13%, and the strong plastic accumulation is 21450 MPa; the tensile strength of the thin area is 1595MPa, the yield strength is 1010MPa, the elongation is 10.0%, and the strength-plastic product is 15546 MPa.
Example 4
The high-strength plastic accumulation difference thick plate for the automobile comprises the following chemical elements in percentage by mass: 0.26% of C, 1.62% of Si, 1.60% of Mn and P:0.002%, S:0.001%, N:0.003%, al:0.04%, and the balance of Fe and unavoidable impurities.
The preparation method of the high-strength plastic accumulation difference thick plate for the automobile comprises the following steps of:
step 1: steelmaking blank making
Smelting in a vacuum smelting furnace of 150kg according to the chemical components of the high-strength and high-plasticity accumulation difference thick plate for the automobile, casting into cast ingots, and forging to obtain billets with the dimensions of 60mm multiplied by 450 mm;
step 2: hot rolling
Heating the billet in a heating furnace to 1200 ℃, preserving heat for 6 hours, rolling on a 450mm hot rolling mill, rolling for 6 times, and then air cooling to obtain a hot rolled plate blank with the thickness of 4.5 mm;
step 3: cold rolling
Pickling the hot-rolled plate blank, cold-rolling to 2.2mm, annealing at 620 ℃, preserving heat for 1 hour, and cooling to room temperature along with a furnace;
step 4: carrying out single-pass variable thickness rolling on a four-roll cold rolling mill after pickling a cold-rolled sheet by variable thickness rolling, and obtaining a differential thick plate with a thick area of 2.0mm, a thin area of 1.0mm and a transition area by dynamically adjusting roll gap rolling in real time, wherein the curve of the transition area is in linear leading transition;
step 5: quenching and distributing heat treatment
Heating the differential thick plate to an austenitizing temperature of 900 ℃ in a heating furnace, preserving heat for 10min, quenching to 270 ℃ in a salt bath, preserving heat for 300s at the temperature, carrying out a carbon distribution process, and finally rapidly quenching and cooling to room temperature to obtain the high-strength plastic differential thick plate.
The scanning structure photo of the high-strength and high-plastic accumulation difference thick plate for the automobile prepared by the embodiment is shown in fig. 6, and the graph shows that most of the structure is lath martensite, and the volume fraction of residual austenite in the thin area and the thick area is 3-6% measured by XRD.
Mechanical property detection is carried out on the high-strength plastic accumulation difference thick plate for the automobile, and the tensile strength of the thick area is 1561MPa, the yield strength is 858MPa, the elongation is 14.8%, and the strong plastic accumulation is 23025 MPa; the tensile strength of the thin area is 1500MPa, the yield strength is 868MPa, the elongation is 10.8%, and the strength-plastic product is 15894 MPa.
Example 5
The high-strength plastic accumulation difference thick plate for the automobile comprises the following chemical elements in percentage by mass: 0.25% of C, 1.58% of Si, 1.55% of Mn and P:0.002%, S:0.001%, N:0.003%, al:0.04%, and the balance of Fe and unavoidable impurities.
The preparation method of the high-strength plastic accumulation difference thick plate for the automobile comprises the following steps of:
step 1: steelmaking blank making
Smelting in a vacuum smelting furnace of 150kg according to the chemical components of the high-strength and high-plasticity accumulation difference thick plate for the automobile, casting into cast ingots, and forging to obtain billets with the dimensions of 60mm multiplied by 450 mm;
step 2: hot rolling
Heating the billet in a heating furnace to 1200 ℃, preserving heat for 6 hours, rolling on a 450mm hot rolling mill, rolling for 6 times, and then air cooling to obtain a hot rolled plate blank with the thickness of 4.5 mm;
step 3: cold rolling
Pickling the hot-rolled plate blank, cold-rolling to 2.2mm, annealing at 620 ℃, preserving heat for 1 hour, and cooling to room temperature along with a furnace;
step 4: variable thickness rolling
Carrying out single-pass variable thickness rolling on a four-roller cold rolling mill after pickling the cold-rolled sheet, and obtaining a differential thick plate with a thick area of 2.0mm and a thin area of 1.0mm and a transition area by dynamically adjusting roll gap rolling in real time, wherein the curve of the transition area is in straight line leading type transition;
step 5: quenching and distributing heat treatment
Heating the differential thick plate to an austenitizing temperature of 900 ℃ in a heating furnace, preserving heat for 10min, quenching to 270 ℃ in a salt bath, preserving heat for 60s at the temperature, carrying out a carbon distribution process, and finally rapidly quenching and cooling to room temperature to obtain the high-strength plastic differential thick plate.
The scanning structure photo of the high-strength plastic accumulation difference thick plate for the automobile prepared by the embodiment is shown in fig. 7, and the graph shows that most of the structure is lath martensite, and the volume fraction of residual austenite in the thin area and the thick area is 3-6% measured by XRD.
Mechanical property detection is carried out on the high-strength plastic accumulation difference thick plate for the automobile, and the tensile strength of a thick area is 1600MPa, the yield strength is 915MPa, the elongation is 14.5%, and the strong plastic accumulation is 23200 MPa; the tensile strength of the thin area is 1564MPa, the yield strength is 928MPa, the elongation is 10.8 percent, and the strength-plastic product is 16808 MPa.
Example 6
The high-strength plastic accumulation difference thick plate for the automobile comprises the following chemical elements in percentage by mass: 0.26% of C, 1.62% of Si, 1.60% of Mn and P:0.002%, S:0.001%, N:0.003%, al:0.04%, and the balance of Fe and unavoidable impurities.
The preparation method of the high-strength plastic accumulation difference thick plate for the automobile comprises the following steps of:
step 1: steelmaking blank making
Smelting in a vacuum smelting furnace of 150kg according to the chemical components of the high-strength and high-plasticity accumulation difference thick plate for the automobile, casting into cast ingots, and forging to obtain billets with the dimensions of 60mm multiplied by 450 mm;
step 2: hot rolling
Heating the billet in a heating furnace to 1200 ℃, preserving heat for 6 hours, rolling on a 450mm hot rolling mill, rolling for 6 times, and then air cooling to obtain a hot rolled plate blank with the thickness of 4.5 mm;
step 3: cold rolling
Pickling the hot-rolled plate blank, cold-rolling to 2.2mm, annealing at 620 ℃, preserving heat for 1 hour, and cooling to room temperature along with a furnace;
step 4: variable thickness rolling
Carrying out single-pass variable thickness rolling on a four-roller cold rolling mill after pickling the cold-rolled sheet, and obtaining a differential thick plate with a thick area of 2.0mm and a thin area of 1.0mm and a transition area by dynamically adjusting roll gap rolling in real time, wherein the curve of the transition area is in straight line leading type transition;
step 5: quenching and distributing heat treatment
Heating the differential thick plate to an austenitizing temperature of 900 ℃ in a heating furnace, preserving heat for 10min, quenching to 270 ℃ in a salt bath, preserving heat for 20s at the temperature, carrying out a carbon distribution process, and finally rapidly quenching and cooling to room temperature to obtain the high-strength plastic differential thick plate.
The scanning structure photo of the high-strength and high-plastic accumulation difference thick plate for the automobile prepared by the embodiment is shown in fig. 8, and the graph shows that most of the structure is lath martensite, and the volume fraction of residual austenite in the thin area and the thick area is 3-6% measured by XRD. FIG. 9 is an X-ray diffraction chart showing the structure of the thin and thick regions of the high-strength and high-plasticity thick plate for automobile prepared in this example.
Mechanical property detection is carried out on the high-strength plastic accumulation difference thick plate for the automobile, and the tensile strength of the thick area is 1620MPa, the yield strength is 1010MPa, the elongation is 15.8%, and the strong plastic accumulation is 25515 MPa; the tensile strength of the thin area is 1562MPa, the yield strength is 990MPa, the elongation is 10.0%, and the product of strength and plastic is 15620 MPa.
Claims (9)
1. The high-strength plastic accumulation difference thick plate for the automobile is characterized by comprising the following chemical elements in percentage by mass: 0.22 to 0.28 percent of C, 1.55 to 1.65 percent of Si, 1.50 to 1.65 percent of Mn, P: less than or equal to 0.002 percent, S: less than or equal to 0.002 percent, N: less than or equal to 0.003 percent, al: less than or equal to 0.04 percent, and the balance of Fe and unavoidable impurities.
2. The automotive high-strength and high-modulus differential plate according to claim 1, wherein the thickness of the thick area of the automotive high-strength and high-modulus differential plate is: the thickness of the thin area is 1.0mm and 2.0mm, and the high-strength plastic accumulation difference thick plate for the automobile is provided with a transition area, and the curve of the transition area is in linear leading transition.
3. The automotive high-strength and high-plastic accumulation difference thick plate according to claim 1, wherein the tensile strength of the automotive high-strength and high-plastic accumulation difference thick plate is more than 1500MPa, and the strong plastic accumulation is more than 15000 MPa; wherein the tensile strength of the thick region is: 1560-1650 MPa, and the yield strength is: 850-1020 MPa, the elongation is 13-16%, and the product of strength and plastic is 21500-25500 MPa; the tensile strength of the thin region is: 1500-1600 MPa, yield strength is: 860-1050 MPa, 10-12% of elongation and 15400-16800 MPa of strength-plastic product.
4. The automotive high-strength and high-plasticity accumulation difference thick plate according to claim 2, wherein the microstructure of the thick area and the thin area of the automotive high-strength and high-plasticity accumulation difference thick plate is mainly: martensite and a small amount of retained austenite.
5. A method for preparing the high-strength and high-plasticity accumulation difference thick plate for automobiles according to any one of claims 1 to 4, which is characterized by comprising the following steps:
step 1: steelmaking blank making
Smelting in a vacuum smelting furnace of 150kg according to the chemical components of the high-strength and high-plasticity accumulation difference thick plate for the automobile, casting into cast ingots, and forging to obtain billets with the dimensions of 60mm multiplied by 450 mm;
step 2: hot rolling
Placing the billet into a heating furnace for heating, then rolling the billet on a 450mm hot rolling mill, rolling for 6 times, and then air-cooling to obtain a hot rolled plate blank with the thickness of 4.5 mm;
step 3: cold rolling
Pickling the hot-rolled plate blank, cold-rolling to 2.2mm, annealing, and cooling to room temperature along with a furnace;
step 4: variable thickness rolling
Carrying out single-pass variable thickness rolling on the cold-rolled sheet after pickling on a four-roll cold-rolling mill, and obtaining a differential thick plate by dynamically adjusting roll gap rolling in real time;
step 5: quenching and distributing heat treatment
And heating the difference thick plate in a heating furnace, then carrying out a quenching carbon distribution process in a salt bath furnace, and finally rapidly quenching and cooling to room temperature to obtain the high-strength plastic accumulation difference thick plate.
6. The method for preparing a thick plate with high strength and elongation for automobiles according to claim 5, wherein the heating temperature in the step 2 is 1200-1250 ℃, and the heat is preserved for 6 hours.
7. The method for preparing a thick plate with high strength and elongation for automobiles according to claim 5, wherein the annealing temperature in the step 3 is 610-630 ℃, and the heat preservation is carried out for 1 hour.
8. The method for manufacturing a thick plate with high strength and elongation for automobiles according to claim 5, wherein the thick plate thickness area in the step 4 is 2.0mm, the thin area is 1.0mm, and the transition area is provided with a transition area, and the curve of the transition area is a straight line dominant transition.
9. The method for preparing a thick plate with high strength and elongation for automobiles according to claim 5, wherein the heating temperature in the step 5 is 900-950 ℃ for 10-20 min, and then the heating temperature is between 250-290 ℃ for 20-300 s for carbon distribution.
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