CN112410668B - 780 MPa-grade steel for automobile structure and production method thereof - Google Patents
780 MPa-grade steel for automobile structure and production method thereof Download PDFInfo
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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
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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
- C21D8/0205—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
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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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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of 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
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
Abstract
The invention relates to 780MPa grade steel for an automobile structure and a production method thereof, wherein the steel comprises the following chemical components in percentage by mass: c: 0.090% -0.13%, Si: 0.02% -0.15%, Mn: 1.65% -1.90%, Al: 0.010% -0.040%, Nb: 0.055% -0.070%, Ti: 0.050% -0.070%, Cr: 0.30-0.40%, Cu: 0.30% -0.65%, Sb: 0.15% -0.30%, Ni: 0.020% to 0.045%, Bi: 0.010-0.045%, P less than or equal to 0.015%, S less than or equal to 0.006%, and the balance of Fe and inevitable impurities. The advantages are that: the steel has excellent mechanical property and corrosion resistance, and a front-section rapid continuous cooling process is adopted after rolling, so that the generation of a banded structure in a steel plate is avoided.
Description
Technical Field
The invention belongs to the field of production of steel for automobile structures, and particularly relates to 780 MPa-grade steel for automobile structures and a production method thereof.
Background
With the rapid development of the automobile industry and the transportation industry in China, the demand of large-tonnage trucks is particularly increased continuously, the purposes of reducing the weight of automobile structural parts to reduce the self weight, saving energy, reducing environmental pollution and improving carrying efficiency are achieved, and the application of high-performance and high-surface-quality hot-rolled automobile steel plates is promoted. The modern automobile industry generally adopts the protection measures for the corrosion of the steel plate to plate zinc on the surface of the steel plate or brush coating anti-corrosion paint, and the automobile steel plate does not have the anti-corrosion performance. Once the anticorrosive coating falls off, the steel plate can be corroded rapidly, so that the steel plate is invalid in use, and the anticorrosive coating can pollute the environment and destroy the ecological environment. Therefore, the hot-rolled steel for automobile structure, which has high corrosion resistance and high surface quality, has improved service life and can occupy the domestic market of steel for automobile structure, has been developed.
The steel plate with the yield strength of more than or equal to 780MPa, the tensile strength of more than or equal to 910MPa and the transverse elongation A of more than or equal to 17 percent is widely applied. In the prior art, Chinese patent application with publication number CN 107641760A discloses a 460 MPa-grade hot-rolled automobile structural steel plate with good fatigue performance and a manufacturing method thereof, a hot-rolled steel plate produced by adding a certain amount of Nb and Ti is designed by utilizing a common C-Mn component system, S, N in steel is fixed by utilizing trace Ti, and the fine grain function of Nb and Ti is fully exerted. But the elongation of the steel plate is up to 22 percent, which does not meet the requirement of high-forming automobile parts and has no corrosion resistance.
The Chinese patent application with publication number CN 107723607A discloses a 420 MPa-grade hot-rolled automobile structural steel plate with excellent cold-forming performance and a manufacturing method thereof, a hot-rolled steel plate produced by adding a certain amount of Nb and Ti is designed by utilizing a common C-Mn component system, S, N in steel is fixed by utilizing trace Ti, the fine grain function of Nb is fully exerted, but the elongation of the steel plate is up to 25 percent, the steel plate does not meet the requirement of high-forming automobile parts, and the steel plate has no corrosion resistance.
Chinese patent application with publication number CN 105369134B discloses a 400 MPa-grade acid-washing-free hot rolled steel plate for an automobile structure and a production method thereof, the hot rolled steel plate is designed by a common C-Mn component system, the strength is improved by solid solution strengthening of carbon and manganese elements, but the yield strength of the steel plate is 311MPa at most, the steel plate does not meet the requirement of high-strength formed automobile parts, and the steel plate has no corrosion resistance.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide 780 MPa-grade steel for automobile structures and a production method thereof, the steel plate has the advantages that the yield strength is more than or equal to 780MPa, the tensile strength is more than or equal to 910MPa, the transverse elongation A is more than or equal to 17%, the corrosion resistance is realized, and the production requirement of high-strength formed automobile parts is met.
In order to achieve the purpose, the invention is realized by the following technical scheme:
the 780 MPa-grade steel for the automobile structure comprises the following chemical components in percentage by mass:
c: 0.090% -0.13%, Si: 0.02% -0.15%, Mn: 1.65% -1.90%, Al: 0.010% -0.040%, Nb: 0.055% -0.070%, Ti: 0.050% -0.070%, Cr: 0.30-0.40%, Cu: 0.30% -0.65%, Sb: 0.15% -0.30%, Ni: 0.020% to 0.045%, Bi: 0.010-0.045%, P less than or equal to 0.015%, S less than or equal to 0.006%, and the balance of Fe and inevitable impurities; the volume percentage of ferrite is 0-15 percent, and the volume percentage of bainite is 85-100 percent.
The structural steel is a hot rolled plate with the yield strength of more than or equal to 780MPa, the tensile strength of more than or equal to 910MPa and the transverse elongation A of more than or equal to 17 percent.
Wherein, the main functions of the chemical components are as follows:
c: carbon is the most important solid solution strengthening element in steel and guarantees the strength of the steel. In view of excellent cold press formability and weldability and dimensional stability after cold pressing, the carbon content cannot be excessively high, and too low a carbon content does not exert a solid solution strengthening effect, and therefore, the carbon content is in the range of 0.090% to 0.13%.
Si: silicon is a solid-solution strengthening element and can contribute to the strength of the steel sheet. However, too high a silicon in the steel affects the hot rolled surface quality. Wherein, the content of the silicon is 0.020-0.15%.
Mn: manganese can form a substitutional solid solution in steel, so that a strong solid solution strengthening effect is achieved, the yield strength and the tensile strength are linearly increased, the steel strength is increased within a certain range, the plasticity and the toughness of the steel are hardly reduced, and the carbon equivalent of the steel can be increased due to the excessively high manganese content. Therefore, the manganese content is selected to be 1.65% -1.95%.
Al: al is a common deoxidizer in steel, a small amount of Al is added into the steel, AlN can be precipitated to play a role in refining grains to a certain extent, the Al also has the oxidation resistance and the corrosion resistance, the combination of the Al, Cr and Si can obviously improve the high-temperature non-peeling performance of the steel and the surface quality of a steel plate, and the Al is too high and is easy to form oxide inclusions, so the content of the Al is limited to 0.010-0.040%.
P: phosphorus increases the temperature at which the alpha phase is formed, and expands the temperature range over which the alpha phase is formed. However, the content of phosphorus is too high, which deteriorates the workability of the steel sheet, and is limited to 0.015% for obtaining a high elongation.
S: since sulfur forms sulfide inclusions such as MnS and becomes a starting point of cracks to deteriorate workability, the content is preferably as small as 0.006%.
Nb: niobium can effectively delay recrystallization of deformed austenite, prevent austenite grains from growing, increase austenite recrystallization temperature, refine grains and improve strength and toughness of steel, and is a strong carbon and nitride forming element which can be combined with carbon and nitrogen to form stable and fine carbon and nitride to play a significant precipitation strengthening role, and the addition of Nb increases recrystallization termination temperature, so that the finish rolling temperature can be carried out at a higher temperature, and the load of a rolling mill is reduced, therefore, the optimal range of the niobium content is between 0.055% and 0.070%.
Ti: is a strong carbide forming element, and adds a trace amount of Ti into the steel, the formed TiC can prevent austenite grains from excessively growing when the steel billet is heated, thereby achieving the purpose of refining the original austenite grains. Ti may also be present in the steel in the form of second phase particles, which play a role in precipitation strengthening, so the Ti addition is 0.050% to 0.070%.
Cr: is a carbide forming element, can delay pearlite transformation and improve the hardenability of the steel. Thereby being beneficial to the formation of bainite structure, refining the structure and playing a role in strengthening. If the chromium content is too high, the workability and formability of the material will be deteriorated. The selection principle of the chromium content is to promote the formation of bainite, so the chromium content of the invention is selected to be 0.30-0.40%.
Cu: the copper element can enlarge an austenite phase region, improve the weather resistance of steel, improve the weldability of the steel and effectively improve the corrosion resistance of the steel, but causes hot brittleness when the Cu content is high, the surface performance of the steel plate is deteriorated, in addition, the copper element is beneficial to the strength and the hot workability of the steel plate under a certain Cu content, the hot rolling edge crack tendency of the steel plate is effectively reduced, and the surface quality of the steel plate is obviously improved. Cu also has the effect of reducing work hardening and improving the plasticity of the steel sheet. Therefore, the copper content is selected to be between 0.30% and 0.65%.
Sb: the antimony element is mainly distributed in the crystal boundary and the crystal grain in the steel, so that the strength of the steel plate is improved, the diffusion rate of elements such as carbon, oxygen and the like on the crystal boundary is reduced, the decarburization and the oxidation phenomena are reduced, the surface and the mechanical property of the steel plate are improved, and the addition of the antimony can promote the surface of a steel plate matrix to form a uniform and compact oxide film (rich in elements such as Sb, Cu, Cr and the like), so that the moisture and oxygen in the air can be effectively prevented from continuously entering the matrix to form a corrosive internal environment, the corrosion resistance of the matrix is improved, and the corrosion resistance of the steel plate is enhanced. The Sb content is too low, so that the passive film is not uniformly dispersed and the integral corrosion resistance effect cannot be achieved; when the content exceeds the upper design limit, the corrosion prevention effect is achieved, but the hot-working performance is obviously reduced, so that the Sb content is limited to 0.15-0.30 percent.
Ni: while nickel does not adversely affect the hardenability and toughness of the steel in the weld heat affected zone, and improves the corrosion resistance of the steel, Ni is a precious element and should not be contained in an excessively high amount. Therefore, the Ni content is limited to 0.020% to 0.045%.
Bi: the bismuth is mainly distributed in the crystal boundary and the crystal grain in the steel, so that the strength of the steel plate is improved, the diffusion rate of elements such as carbon, oxygen and the like on the crystal boundary is reduced, the decarburization and the oxidation phenomena are reduced, and the surface and the mechanical property of the steel plate are improved. Therefore, the Bi content is limited to 0.010% to 0.045%.
A production method of 780 MPa-grade steel for automobile structures comprises the working procedures of smelting, heating and rolling, wherein the rolling working procedure adopts 6 racks for finish rolling production, and the specific production method comprises the following steps:
1) a heating process: directly hot-charging (170) 230 mm thick x (1550-1880) mm wide continuous casting slabs into a stepping heating furnace for heating, wherein the hot charging temperature is more than 750 ℃, a preheating section is preheated at the furnace gas temperature of 800-1000 ℃, the preheating time is 25-30 min, the temperatures of a heating section 1 and a heating section 2 are respectively controlled at 1120-1200 ℃ and 1210-1240 ℃, the total time of the heating section 1 and the heating section 2 is 15-20 min, the temperature of a soaking section is 1220-1240 ℃, the soaking time is 65-110 min, the furnace pressure is in a micro-positive pressure state, and the positive pressure value is controlled at 3-15 Pa;
2) the rolling process comprises the following steps: the rough rolling adopts 6-pass rolling and 3-pass descaling processes, the first rough rolling machine R1 descales in 1, 3 and 5 passes, the upper and lower 2 rows of water spraying headers of the descaling box are opened simultaneously, and the pressure of a high-pressure water outlet is 21-30 MPa; the outlet temperature of rough rolling is 1050-1090 ℃, the thickness of the intermediate blank is 30-40 mm, the width is 1550-1880 mm, the intermediate blank is insulated by a heat-insulating cover before entering a hot rolling finishing mill group, the finish rolling is 6-frame continuous rolling, high-pressure water descaling is carried out before finish rolling, the inlet temperature of finish rolling is not higher than 1060 ℃, the finish rolling temperature is 850-; meanwhile, the F5 and F6 frames are descaled by adopting high water pressure of 21-30 MPa, cooling water between the other frames is completely started, the convexity control precision of the steel plate is +/-13 mu m, the flatness is controlled within 25I, the thickness control precision is +/-25 mu m, and the thickness of a finished product is 3-10 mm.
The finish rolling in the step 2) adopts high-tension rolling: the tension between the frames of the first frame finishing mill F1 and the second frame finishing mill F2 is controlled to be 8-15N/mm2The tension between the frames of the second finishing mill F2 and the third finishing mill F3 is controlled to be 14-23N/mm2The tension between the stands of the third finishing mill F3 and the fourth finishing mill F4 is controlled to be 14-22N/mm2The tension between the stands of the fourth finishing mill F4 and the fifth finishing mill F5 is controlled to be 9-18N/mm2The tension between the frames of the fifth finishing mill F5 and the sixth finishing mill F6 is controlled to be 6-11N/mm2。
The method also comprises a cooling process: and after the final rolling, adopting front-section rapid continuous laminar cooling, wherein the cooling rate is 55-65 ℃/s.
Further comprising a coiling temperature: the coiling temperature is 570-610 ℃.
Compared with the prior art, the invention has the beneficial effects that:
1. the addition of Nb increases the recrystallization termination temperature, so that the finish rolling temperature can be carried out at a higher temperature, and the load of a rolling mill is reduced;
2. the addition of Cu expands an austenite phase region, improves the weather resistance of steel, improves the weldability of steel and can also effectively improve the corrosion resistance of steel;
3. the addition of Sb can reduce the diffusion rate of elements such as carbon, oxygen and the like on a crystal boundary, reduce the phenomena of decarburization and oxidation, improve the surface and the mechanical property of the steel plate, and promote the surface of a steel plate matrix to form a layer of uniform and compact oxide film (rich in elements such as Sb, Cu, Cr and the like) by the addition of Sb, so that air moisture and oxygen can be effectively prevented from continuously entering the matrix to form a corrosive internal environment, the corrosion resistance of the matrix is improved, and the corrosion resistance of the steel plate is enhanced;
4. the addition of Ni has no adverse effect on the hardenability and the toughness of the welding heat affected zone of the steel, and simultaneously can improve the corrosion resistance of the steel;
5. bi: the bismuth is mainly distributed in the crystal boundary and the crystal grain in the steel, so that the strength of the steel plate is improved, the diffusion rate of elements such as carbon, oxygen and the like on the crystal boundary is reduced, the decarburization and the oxidation phenomena are reduced, and the surface and the mechanical property of the steel plate are improved.
6. And a front-section rapid continuous cooling process is adopted after rolling, so that the generation of a band-shaped structure in a steel plate is avoided.
7. The invention has excellent mechanical property and corrosion resistance, is used for steel for automobile structures, and has yield strength of more than or equal to 780MPa, tensile strength of more than or equal to 910MPa and transverse elongation A of more than or equal to 17 percent.
Detailed Description
The present invention is described in detail below, but it should be noted that the practice of the present invention is not limited to the following embodiments.
The 780 MPa-grade steel for the automobile structure comprises the following chemical components in percentage by mass:
c: 0.090% -0.13%, Si: 0.02% -0.15%, Mn: 1.65% -1.90%, Al: 0.010% -0.040%, Nb: 0.055% -0.070%, Ti: 0.050% -0.070%, Cr: 0.30-0.40%, Cu: 0.30% -0.65%, Sb: 0.15% -0.30%, Ni: 0.020% to 0.045%, Bi: 0.010-0.045%, P less than or equal to 0.015%, S less than or equal to 0.006%, and the balance of Fe and inevitable impurities. The volume percentage of ferrite and bainite in the final structure is 0-15 percent and 85-100 percent respectively, and the hot rolled plate with the yield strength of more than 780MPa, the tensile strength of more than 910MPa and the transverse elongation A of more than 17 percent is obtained.
The invention adopts the chemical components, adopts 6 frames to carry out finish rolling production through smelting and hot rolling procedures, and the specific manufacturing method comprises the following steps:
(1) a heating process: directly hot-charging (170) 230 mm thick x (1550-1880) mm wide continuous casting slabs into a stepping heating furnace for heating, wherein the hot-charging temperature is more than 750 ℃, the preheating section is preheated at the furnace gas temperature of 800-1000 ℃, the preheating time is 25-30 min, the temperatures of the heating section 1 and the heating section 2 are respectively controlled at 1120-1200 ℃ and 1210-1240 ℃, the heating time is 15-20 min (the heating time of the heating section 1 and the heating section 2), the temperature of the soaking section is 1220-1240 ℃, the soaking time is 65-110 min, the furnace pressure is in a micro-positive pressure state, the positive pressure value is controlled at 3-15 Pa, and the oxidation burning loss is reduced. The proper heating temperature and the proper heat preservation time enable alloy elements in the plate blank to be completely dissolved in solid solution and the plate blank components to be uniform, and the effects of controlling the size of original austenite grains, saving energy and the like are achieved.
(2) The rolling process comprises the following steps: the rough rolling adopts 6-pass rolling and 3-pass descaling processes, the first rough rolling machine R1 descales in 1, 3 and 5 passes, the upper and lower 2 rows of water spraying headers of the descaling box are opened simultaneously, and the pressure of a high-pressure water outlet is 21-30 MPa; the rough rolling outlet temperature is 1050-1090 ℃, the thickness of the intermediate blank is 30-40 mm, the width is 1550-1880 mm, the intermediate blank is insulated by a heat insulation cover before entering a hot rolling finishing mill group, the temperature drop of the intermediate blank on a delay roller way and the temperature difference in the head-tail direction and the plate width direction are reduced, the finish rolling is 6-stand continuous rolling, high-pressure water descaling is carried out before the finish rolling, the finish rolling inlet temperature is not higher than 1060 ℃, the finish rolling temperature is 850-930 ℃, the finish rolling adopts high-tension rolling, the tension between a first finishing mill F1 and a second finishing mill F2 stand is controlled at 8-15N/mm2The tension between the frames of the second finishing mill F2 and the third finishing mill F3 is controlled to be 14-23N/mm2The tension between the stands of the third finishing mill F3 and the fourth finishing mill F4 is controlled to be 14-22N/mm2Fourth finishing mill FThe tension between the frame 4 and the frame F5 of the fifth finishing mill is controlled to be 9-18N/mm2The tension between the frames of the fifth finishing mill F5 and the sixth finishing mill F6 is controlled to be 6-11N/mm2Meanwhile, the F5 and F6 frames adopt high-pressure water (21-30 MPa) for descaling, cooling water between the other frames is completely opened, the convexity control precision of the steel plate is +/-13 microns, the flatness is controlled within 25I, the thickness control precision is +/-25 microns, and the thickness of a finished product is 3-10 mm.
(3) And (3) a cooling process: and after the final rolling, adopting front-section rapid continuous laminar cooling, wherein the cooling rate is 55-65 ℃/s. The continuous laminar cooling process makes bainite precipitate fast in great amount, and this can inhibit the growth of crystal grains and ensure the bainite content, so as to refine the bainite crystal grains.
(4) Coiling temperature: the coiling temperature is 570-610 ℃. The coiling temperature is too high, so that the strength of the steel plate is insufficient, the elongation is reduced due to too low coiling temperature, the second phase particles can be fully precipitated after the steel plate is coiled in a temperature range, and the plasticity is good.
Examples
The specific components, temperature system, finishing tension control parameters, properties of the steel sheet and the percentage of the structure volume of 6 examples of the invention are shown in tables 1 to 5.
TABLE 1 chemical composition of inventive examples (wt%)
TABLE 2 Hot Rolling temperature System of examples of the present invention
TABLE 3 examples finishing tension control parameters
TABLE 4 mechanical Property parameters of the examples of the invention
TABLE 5 percentage of tissue volume in the examples of the invention
| Numbering | Ferrite | Bainite for treating cancer |
| Example 1 | 0％ | 100％ |
| Example 2 | 10％ | 90％ |
| Example 3 | 8％ | 92％ |
| Example 4 | 14％ | 86％ |
| Example 5 | 11％ | 89％ |
| Example 6 | 15％ | 85％ |
。
Claims (3)
1. A production method of 780 MPa-grade steel for automobile structures comprises the following chemical components in percentage by mass:
c: 0.090% -0.13%, Si: 0.02% -0.15%, Mn: 1.65% -1.90%, Al: 0.010-0.040%, Nb: 0.055% -0.070%, Ti: 0.050% -0.070%, Cr: 0.30% -0.40%, Cu: 0.30% -0.65%, Sb: 0.15% -0.30%, Ni: 0.020% to 0.045%, Bi: 0.010-0.045%, P less than or equal to 0.015%, S less than or equal to 0.006%, and the balance of Fe and inevitable impurities; ferrite volume percentage is 0% -15%, bainite volume percentage is 85% -100%; the production method is characterized by comprising the working procedures of smelting, heating and rolling, wherein the rolling working procedure adopts 6 racks for finish rolling production, and the specific production method comprises the following steps:
1) a heating process: directly hot-charging (170) 230 mm thick x (1550-1880) mm wide continuous casting slabs into a heating furnace for heating, wherein the hot charging temperature is more than 750 ℃, the preheating section is preheated at the furnace gas temperature of 800-1000 ℃, the preheating time is 25-30 min, the temperatures of the heating 1 section and the heating 2 section are respectively controlled at 1120-1200 ℃ and 1210-1240 ℃, the total soaking time of the heating 1 section and the heating 2 section is 15-20 min, the temperature of the heating 1 section is 1220-1240 ℃, the soaking time is 65-110 min, the furnace pressure is in a micro-positive pressure state, and the positive pressure value is controlled at 3-15 Pa;
2) the rolling process comprises the following steps: the rough rolling adopts 6-pass rolling and 3-pass descaling processes, the first rough rolling machine R1 descales in 1, 3 and 5 passes, the upper and lower 2 rows of water spraying headers of the descaling box are opened simultaneously, and the pressure of a high-pressure water outlet is 21-30 MPa; the outlet temperature of rough rolling is 1050-1090 ℃, the thickness of the intermediate blank is 30-40 mm, the width is 1550-1880 mm, the intermediate blank is insulated by a heat-insulating cover before entering a hot rolling finishing mill group, the finish rolling is 6-frame continuous rolling, high-pressure water descaling is carried out before finish rolling, the inlet temperature of finish rolling is not higher than 1060 ℃, the finish rolling temperature is 850-; meanwhile, the F5 and F6 frames are descaled by adopting high water pressure of 21-30 MPa, cooling water between the other frames is completely started, the convexity control precision of the steel plate is +/-13 mu m, the flatness is controlled within 25I, the thickness control precision is +/-25 mu m, and the thickness of a finished product is 3-10 mm; and (3) a cooling process: adopting front-section rapid continuous laminar cooling after final rolling, wherein the cooling rate is 55-65 ℃/s; and (3) a coiling process: the coiling temperature is 570-610 ℃.
2. The production method of 780MPa grade steel for automobile structures according to claim 1, wherein the finish rolling in step 2) is performed by high tension rolling: the tension between the frames of the first frame finishing mill F1 and the second frame finishing mill F2 is controlled between 8 and 15N/mm2The tension between the frames of the second finishing mill F2 and the third finishing mill F3 is controlled to be 14-23N/mm2The tension between the stands of the third finishing mill F3 and the fourth finishing mill F4 is controlled to be 14-22N/mm2The tension between the stands of the fourth finishing mill F4 and the fifth finishing mill F5 is controlled to be 9-18N/mm2The tension between the frames of the fifth finishing mill F5 and the sixth finishing mill F6 is controlled to be 6-11N/mm2。
3. The production method of 780 MPa-grade steel for automobile structures according to claim 1, characterized in that the yield strength of the steel for structures is not less than 780MPa, the tensile strength is not less than 910MPa, and the transverse elongation A is not less than 17%.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108884536A (en) * | 2016-03-28 | 2018-11-23 | Posco公司 | Yield strength and excellent high strength cold rolled steel plate, coated steel sheet and their manufacturing method of ductility |
| CN109023071A (en) * | 2018-09-04 | 2018-12-18 | 鞍钢股份有限公司 | A kind of resistance to neutral soil corrodes buried structural steel and its manufacturing method |
| CN109023070A (en) * | 2018-09-04 | 2018-12-18 | 鞍钢股份有限公司 | A kind of buried structural steel of resistance to salt marsh soil corrosion and its manufacturing method |
| CN109082594A (en) * | 2018-09-04 | 2018-12-25 | 鞍钢股份有限公司 | A kind of buried structural steel of acid resistance soil corrosion and its manufacturing method |
| CN109082595A (en) * | 2018-09-04 | 2018-12-25 | 鞍钢股份有限公司 | A kind of buried structural steel of alkaline soil corrosion-resistant and its manufacturing method |
| CN110669989A (en) * | 2019-09-30 | 2020-01-10 | 鞍钢股份有限公司 | High-elongation steel for automobile axle housing for cold stamping and production method thereof |
| CN110669914A (en) * | 2019-09-30 | 2020-01-10 | 鞍钢股份有限公司 | High-strength steel for automobile axle housing for cold stamping and production method thereof |
-
2020
- 2020-11-11 CN CN202011252583.9A patent/CN112410668B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108884536A (en) * | 2016-03-28 | 2018-11-23 | Posco公司 | Yield strength and excellent high strength cold rolled steel plate, coated steel sheet and their manufacturing method of ductility |
| CN109023071A (en) * | 2018-09-04 | 2018-12-18 | 鞍钢股份有限公司 | A kind of resistance to neutral soil corrodes buried structural steel and its manufacturing method |
| CN109023070A (en) * | 2018-09-04 | 2018-12-18 | 鞍钢股份有限公司 | A kind of buried structural steel of resistance to salt marsh soil corrosion and its manufacturing method |
| CN109082594A (en) * | 2018-09-04 | 2018-12-25 | 鞍钢股份有限公司 | A kind of buried structural steel of acid resistance soil corrosion and its manufacturing method |
| CN109082595A (en) * | 2018-09-04 | 2018-12-25 | 鞍钢股份有限公司 | A kind of buried structural steel of alkaline soil corrosion-resistant and its manufacturing method |
| CN110669989A (en) * | 2019-09-30 | 2020-01-10 | 鞍钢股份有限公司 | High-elongation steel for automobile axle housing for cold stamping and production method thereof |
| CN110669914A (en) * | 2019-09-30 | 2020-01-10 | 鞍钢股份有限公司 | High-strength steel for automobile axle housing for cold stamping and production method thereof |
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