CN112080692A - 280 MPa-grade cold-rolled low-yield-ratio stamping steel for automobile structure and production method thereof - Google Patents
280 MPa-grade cold-rolled low-yield-ratio stamping 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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- 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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- 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
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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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- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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Abstract
The invention discloses a 280 MPa-grade cold-rolled low-yield-ratio stamping steel for an automobile structure, which comprises the following chemical components in percentage by mass: c: 0.06-0.07%, Si: 0.15-0.18%, Mn: 1.40-1.46%, P: less than or equal to 0.010 percent, S: less than or equal to 0.005 percent, Alt: 0.020-0.050%, Ca: 0.0010-0.0030% and the balance of Fe and inevitable impurities; its preparing process is also disclosed. The automobile steel for the cold-rolled low-yield-ratio stamping structure has the characteristics of high strength and low yield ratio, and is widely applied to automobile reinforcements and structural parts. The requirements of light weight and material selection of the automobile are met, and the mechanical property and the process property meet the relevant standards and the requirements of users.
Description
Technical Field
The invention relates to the technical field of metallurgical plate production, in particular to 280 MPa-grade cold-rolled low-yield-ratio stamping steel for an automobile structure and a production method thereof.
Background
With the high-speed development of the automobile industry and the requirements of energy conservation and emission reduction, lightweight materials are adopted in large quantities by automobile production. In recent years, in order to meet the development requirements of weight reduction, energy conservation and safety of the modern automobile industry, the research and development of cold-rolled high-strength steel plates for automobiles are enhanced by all iron and steel enterprises which produce cold-rolled high-strength steel at home and abroad. In automobile manufacturing, stressed structural members and reinforcements such as automobile chassis and wheelchair supports need to have good deformation resistance, i.e. high yield strength, and for part of stamped parts, low yield ratio.
The application of a large amount of high-strength steel not only plays a role in energy conservation and emission reduction, but also can improve the safety performance of the automobile, maintain the production cost of the automobile and improve the recycling rate of the automobile.
The cold-rolled low-alloy high-strength steel is a high-strength steel developed for automobile structural members, and is a steel material with better performance than general carbon steel obtained by adding a small amount of or trace alloy elements into common low-carbon steel and adopting the modes of solid solution strengthening (or precipitation strengthening, fine grain strengthening), incomplete annealing and the like. Typical marks are B280VK, HC340LA, HC420LA and the like, have the characteristics of high strength, high yield ratio, high rigidity and low plasticity, and are widely applied to materials of automobile reinforcements and structural parts.
The BT280VK cold-rolled steel strip belongs to cold-rolled low-yield-ratio stamping structure automobile steel, 280 in the mark represents the minimum yield value, V represents low alloy high strength, the difference value between the yield point and the tensile strength is not specified, and K represents calm and fine-grained steel. The cold-rolled sheet is mainly used for reinforcing structural members such as frames, columns and beams of small automobiles, which have high requirements on strength and forming performance of materials. BT280VK in domestic market mainly comprises Bao steel B280VK, Pan steel P280VK, ripple steel L280VK and the like.
Disclosure of Invention
The invention aims to solve the technical problem of providing the 280 MPa-grade cold-rolled steel for the stamping structure with the low yield ratio and the production method thereof. The requirements of light weight and material selection of the automobile are met, and the mechanical property and the process property meet the relevant standards and the requirements of users.
In order to solve the technical problems, the invention adopts the following technical scheme:
the 280 MPa-grade cold-rolled low-yield-ratio stamping steel for the automobile structure comprises the following chemical components in percentage by mass: c: 0.06-0.07%, Si: 0.15-0.18%, Mn: 1.40-1.46%, P: less than or equal to 0.010 percent, S: less than or equal to 0.005 percent, Alt: 0.020-0.050%, Ca: 0.0010-0.0030% and the balance of Fe and inevitable impurities.
Further, the chemical components comprise the following components in percentage by mass: c: 0.07%, Si: 0.177%, Mn: 1.40%, P: 0.012%, S: 0.005%, Alt: 0.050%, Ca: 0.0010 percent, and the balance of Fe and inevitable impurities.
Further, the chemical components comprise the following components in percentage by mass: c: 0.07%, Si: 0.185%, Mn: 1.41%, P: 0.014%, S: 0.004%, Alt: 0.038%, Ca: 0.0010 percent, and the balance of Fe and inevitable impurities.
Further, the chemical components comprise the following components in percentage by mass: c: 0.07%, Si: 0.172%, Mn: 1.43%, P: 0.013%, S: 0.003%, Alt: 0.040%, Ca: 0.0010 percent, and the balance of Fe and inevitable impurities.
A production method of a 280 MPa-grade cold-rolled low-yield-ratio stamping steel for automobile structures comprises the following steps:
(1) the smelting-continuous casting production process flow comprises the following steps: pretreatment of molten iron, converter, LF refining and casting machine; the molten steel for the casting machine comprises the following components: 0.06-0.07%, Si: 0.15-0.18%, Mn: 1.40-1.52%, P: less than or equal to 0.010 percent, S: less than or equal to 0.005 percent, Alt: 0.020-0.050%, Ca: 0.0010-0.0030%;
(2) the hot rolling production process flow comprises the following steps: heating a casting blank, rough rolling, finish rolling and coiling; the tapping temperature of the casting blank is 1220 +/-20 ℃, the rough rolling is carried out by adopting a 3+3 mode 2-frame rolling mill, the finish rolling is carried out by adopting a 7-frame continuous variable-crown rolling mill, and the thickness of the intermediate blank is 40-45 mm; the finish rolling temperature of finish rolling is 870 +/-20 ℃, and the thickness of the hot rolled steel strip is 3.5 mm; laminar flow cooling equipment is adopted for cooling, a front dispersive cooling mode is adopted, and the coiling temperature is 580 +/-20 ℃;
(3) acid washing cold rolling process flow: pickling the hot-rolled strip steel by using a hydrochloric acid tank of an i-BOX technology, removing surface iron scales, cold-rolling by using a 5-stand cold rolling mill, wherein the cold-rolling reduction rate is 65.7%, and rolling to the target thickness;
(4) the continuous annealing process flow comprises the following steps: uncoiling the cold-hard coil steel strip, heating to 780 +/-10 ℃, soaking for 150-.
Further, the method specifically comprises the following steps:
carrying out desulfurization pretreatment on molten iron, carrying out decarburization and dephosphorization on the molten iron by adopting a top-bottom combined blown converter to obtain molten steel, blowing argon in the whole smelting process of the converter, adding scrap steel into the converter, and carrying out tapping temperature of the converter of 1630 ℃; then, carrying out LF external refining on the molten steel smelted by the converter, wherein the refining in-place temperature is more than or equal to 1560 ℃, and carrying out temperature measurement and component fine adjustment by the LF external refining; the superheat degree of the continuous casting of the plate blank is 22 ℃, and then the plate blank is cleaned, slowly cooled and the quality of the continuous casting blank is checked; the heating temperature of the plate blank is 1220 ℃, the heating time is 205min, and the heated plate blank is subjected to high-pressure water dephosphorization; the width is fixed by a width fixing press, 2 frames are adopted for rough rolling, and 7 frames are adopted for CVC finish rolling; the finish rolling temperature is 875 ℃, and the thickness of a finished product is 3.5 mm; the laminar cooling adopts pre-dispersion cooling, and the temperature of the steel strip is reduced to 588 ℃ for coiling; pickling the hot-rolled strip steel by a hydrochloric acid tank, wherein the acid tank adopts an i-BOX technology newly developed by MH, removing surface iron scale of the hot-rolled strip steel, cold-rolling the hot-rolled strip steel by a 5-frame UCM rolling mill, and rolling the cold-rolled strip steel to a target thickness with a cold-rolling reduction rate of 65.7%; the cold-hard coil continuous annealing is carried out in a continuous vertical annealing furnace with HGJC function, the running speed of the steel strip is 100m/min, the soaking temperature is 790 ℃, the soaking time is 170S, the slow cooling temperature is 670 ℃, the fast cooling speed is 30 ℃/S, the overaging temperature is 320 ℃, and the leveling elongation is 0.6%.
Further, the method specifically comprises the following steps:
carrying out desulfurization pretreatment on molten iron, carrying out decarburization and dephosphorization on the molten iron by adopting a top-bottom combined blown converter to obtain molten steel, blowing argon in the whole smelting process of the converter, adding scrap steel into the converter, and carrying out tapping at 1648 ℃ by the converter; then, carrying out LF external refining on the molten steel smelted by the converter, wherein the refining in-place temperature is more than or equal to 1560 ℃, and carrying out temperature measurement and component fine adjustment by the LF external refining; the superheat degree of the continuous casting of the plate blank is 23 ℃, and then the plate blank is cleaned, slowly cooled and the quality of the continuous casting blank is checked; heating the plate blank at 1218 ℃ for 202min, and removing phosphorus from the heated plate blank with high-pressure water; the width is fixed by a width fixing press, 2 frames are adopted for rough rolling, and 7 frames are adopted for CVC finish rolling; the finish rolling temperature is 877 ℃, and the thickness of the finished product is 3.5 mm; the laminar cooling adopts pre-dispersion cooling, and the temperature of the steel strip is reduced to 590 ℃ for coiling; pickling the hot-rolled strip steel by a hydrochloric acid tank, wherein the acid tank adopts an i-BOX technology newly developed by MH, removing surface iron scale of the hot-rolled strip steel, cold-rolling the hot-rolled strip steel by a 5-frame UCM rolling mill, and rolling the cold-rolled strip steel to a target thickness with a cold-rolling reduction rate of 65.7%; the cold-hard coil continuous annealing is carried out in a continuous vertical annealing furnace with HGJC function, the running speed of the steel strip is 85m/min, the soaking temperature is 765 ℃, the soaking time is 200S, the slow cooling temperature is 678 ℃, the fast cooling speed is 26 ℃/S, the fast cooling temperature is 318 ℃, and the leveling elongation is 0.6%.
Compared with the prior art, the invention has the beneficial technical effects that:
the invention has the beneficial effects that the 280 MPa-grade cold-rolled low-yield-ratio stamping structure steel for the automobile and the production method thereof are provided, the metallographic microstructure of the steel is ferrite, and the grain size is between 11.0 grade and 11.5 grade. The automobile steel for the 280 MPa-grade cold-rolled low-yield-ratio stamping structure produced by the method provided by the invention has the advantages that through stamping use tests of automobile factories, all indexes of surface quality and performance meet the requirements of relevant technical standards of the automobile factories, and the use requirements of the relevant automobile factories are met. The mechanical property and the process property meet the relevant standards and the user requirements. Meanwhile, the alloy of the invention has low cost and simple preparation method, and is suitable for industrial production.
Drawings
The invention is further illustrated in the following description with reference to the drawings.
FIG. 1 is a microstructure diagram of example 1 of the present invention.
Detailed Description
The present invention is described in more detail below by way of specific examples. The examples are merely illustrative of the best mode of carrying out the invention and do not limit the scope of the invention in any way.
Example 1
The method comprises the following steps of carrying out desulfurization pretreatment on molten iron, carrying out dephosphorization and decarburization on the molten iron by adopting a top-bottom combined blown converter to obtain molten steel, blowing argon in the whole process of the converter smelting, adding scrap steel into the converter, and carrying out tapping at 1628 ℃. And then, carrying out LF external refining on the molten steel smelted by the converter, wherein the refining in-place temperature is more than or equal to 1560 ℃, carrying out temperature measurement and component fine adjustment on the LF external refining, and the chemical components of the ladle casting machine for the LF external refining are shown in Table 1. The superheat degree of the slab continuous casting is 20 ℃, and then slab cleaning, slow cooling and quality inspection of the continuous casting slab are carried out. And (3) heating the plate blank at 1215 ℃, heating for 203min, and carrying out high-pressure water dephosphorization on the heated plate blank. The width is fixed by a width fixing press, 2 frames are adopted for rough rolling, and 7 frames are adopted for CVC finish rolling. The finish rolling temperature is 872 ℃, and the thickness of the finished product is 3.5 mm. And the laminar cooling adopts pre-dispersion cooling, and the temperature of the steel strip is reduced to 593 ℃ for coiling. The hot-rolled strip steel is pickled by a hydrochloric acid tank, the acid tank adopts an i-BOX technology newly developed by MH, the operation and maintenance are greatly simplified, the energy and labor force are saved, after the surface oxide scale of the hot-rolled strip steel is removed, the hot-rolled strip steel is cold-rolled by a 5-frame UCM rolling mill, the cold-rolling reduction rate is 65.7 percent, and the target thickness is 1.2 mm. The cold-hard coil continuous annealing is carried out in a continuous vertical annealing furnace with HGJC function, the running speed of the steel strip is 90m/min, the soaking temperature is 785 ℃, the soaking time is 190S, the slow cooling temperature is 680 ℃, the fast cooling speed is 27 ℃/S, the fast cooling temperature is 320 ℃, and the flat elongation is 0.6%. And finally, detecting the product performance. The microstructure is ferrite as shown in figure 1, and the grain size is between 11.0 grade and 11.5 grade.
Example 2
The method comprises the following steps of carrying out desulfurization pretreatment on molten iron, carrying out decarburization and dephosphorization on the molten iron by adopting a top-bottom combined blown converter to obtain molten steel, blowing argon in the whole process of the converter smelting, adding scrap steel into the converter, and carrying out tapping at 1630 ℃. And then, carrying out LF external refining on the molten steel smelted by the converter, wherein the refining in-place temperature is more than or equal to 1560 ℃, carrying out temperature measurement and component fine adjustment on the LF external refining, and the chemical components of the ladle casting machine for the LF external refining are shown in Table 1. The superheat degree of the continuous casting of the slab is 22 ℃, and then slab cleaning, slow cooling and continuous casting slab quality inspection are carried out. The heating temperature of the plate blank is 1220 ℃, the heating time is 205min, and the heated plate blank is subjected to high-pressure water dephosphorization. The width is fixed by a width fixing press, 2 frames are adopted for rough rolling, and 7 frames are adopted for CVC finish rolling. The finish rolling temperature is 875 ℃, and the thickness of the finished product is 3.5 mm. And the laminar cooling adopts pre-dispersion cooling, and the temperature of the steel strip is reduced to 588 ℃ for coiling. The hot-rolled strip steel is pickled by a hydrochloric acid tank, the acid tank adopts an i-BOX technology newly developed by MH, the operation and maintenance are greatly simplified, the energy and labor force are saved, after the surface oxide scale of the hot-rolled strip steel is removed, the hot-rolled strip steel is cold-rolled by a 5-frame UCM rolling mill, the cold-rolling reduction rate is 65.7 percent, and the target thickness is 1.2 mm. The cold-hard coil continuous annealing is carried out in a continuous vertical annealing furnace with HGJC function, the running speed of the steel strip is 100m/min, the soaking temperature is 790 ℃, the soaking time is 170S, the slow cooling temperature is 670 ℃, the fast cooling speed is 30 ℃/S, the overaging temperature is 320 ℃, and the leveling elongation is 0.6%. And finally, detecting the product performance.
Example 3
The method comprises the following steps of carrying out desulfurization pretreatment on molten iron, carrying out decarburization and dephosphorization on the molten iron by adopting a top-bottom combined blown converter to obtain molten steel, blowing argon in the whole process of the converter smelting, adding scrap steel into the converter, and carrying out steel tapping at the temperature of 1648 ℃. And then, carrying out LF external refining on the molten steel smelted by the converter, wherein the refining in-place temperature is more than or equal to 1560 ℃, carrying out temperature measurement and component fine adjustment on the LF external refining, and the chemical components of the ladle casting machine for the LF external refining are shown in Table 2. The superheat degree of the continuous casting of the slab is 23 ℃, and then slab cleaning, slow cooling and continuous casting slab quality inspection are carried out. The heating temperature of the plate blank is 1218 ℃, the heating time is 202min, and the heated plate blank is subjected to high-pressure water dephosphorization. The width is fixed by a width fixing press, 2 frames are adopted for rough rolling, and 7 frames are adopted for CVC finish rolling. The finish rolling temperature is 877 ℃, and the thickness of the finished product is 3.5 mm. And adopting front dispersion cooling for laminar cooling, and reducing the temperature of the steel strip to 590 ℃ for coiling. The hot-rolled strip steel is pickled by a hydrochloric acid tank, the acid tank adopts an i-BOX technology newly developed by MH, the operation and maintenance are greatly simplified, the energy and labor force are saved, after the surface oxide scale of the hot-rolled strip steel is removed, the hot-rolled strip steel is cold-rolled by a 5-frame UCM rolling mill, the cold-rolling reduction rate is 65.7 percent, and the target thickness is 1.2 mm. The cold-hard coil continuous annealing is carried out in a continuous vertical annealing furnace with HGJC function, the running speed of the steel strip is 85m/min, the soaking temperature is 765 ℃, the soaking time is 200S, the slow cooling temperature is 678 ℃, the fast cooling speed is 26 ℃/S, the fast cooling temperature is 318 ℃, and the leveling elongation is 0.6%. And finally, detecting the product performance.
TABLE 1 chemical composition (wt%) of inventive examples 1 to 3
| Examples | C | Si | Mn | P | S | Alt | N | Ca |
| 1 | 0.07 | 0.177 | 1.40 | 0.012 | 0.005 | 0.050 | 0.005 | 0.001 |
| 2 | 0.07 | 0.185 | 1.41 | 0.014 | 0.004 | 0.038 | 0.004 | 0.001 |
| 3 | 0.07 | 0.172 | 1.43 | 0.013 | 0.003 | 0.040 | 0.004 | 0.001 |
Mechanical property test is carried out on the steel coils of the embodiments 1-3 of the invention, and the test results are shown in table 2.
TABLE 2 mechanical properties of steel coils according to the invention in examples 1 to 3
As can be seen from the data in Table 2, the mechanical properties and the processing properties of the automotive steel for the 280 MPa-grade cold-rolled low yield ratio stamping structure produced by the method provided by the invention meet the requirements of the agreement signed by the user.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (7)
1. The 280 MPa-grade cold-rolled low-yield-ratio stamping steel for the automobile structure is characterized by comprising the following chemical components in percentage by mass: c: 0.06-0.07%, Si: 0.15-0.18%, Mn: 1.40-1.46%, P: less than or equal to 0.010 percent, S: less than or equal to 0.005 percent, Alt: 0.020-0.050%, Ca: 0.0010-0.0030% and the balance of Fe and inevitable impurities.
2. The steel for the 280 MPa-grade cold-rolled low-yield-ratio stamped automobile structure as claimed in claim 1, wherein the steel comprises the following chemical components in percentage by mass: c: 0.07%, Si: 0.177%, Mn: 1.40%, P: 0.012%, S: 0.005%, Alt: 0.050%, Ca: 0.0010 percent, and the balance of Fe and inevitable impurities.
3. The steel for the 280 MPa-grade cold-rolled low-yield-ratio stamped automobile structure as claimed in claim 1, wherein the steel comprises the following chemical components in percentage by mass: c: 0.07%, Si: 0.185%, Mn: 1.41%, P: 0.014%, S: 0.004%, Alt: 0.038%, Ca: 0.0010 percent, and the balance of Fe and inevitable impurities.
4. The steel for the 280 MPa-grade cold-rolled low-yield-ratio stamped automobile structure as claimed in claim 1, wherein the steel comprises the following chemical components in percentage by mass: c: 0.07%, Si: 0.172%, Mn: 1.43%, P: 0.013%, S: 0.003%, Alt: 0.040%, Ca: 0.0010 percent, and the balance of Fe and inevitable impurities.
5. The method for producing the steel for the 280MPa grade cold rolling low yield ratio stamping automobile structure as claimed in claim 1, is characterized by comprising the following steps:
(1) the smelting-continuous casting production process flow comprises the following steps: pretreatment of molten iron, converter, LF refining and casting machine; the molten steel for the casting machine comprises the following components: 0.06-0.07%, Si: 0.15-0.18%, Mn: 1.40-1.52%, P: less than or equal to 0.010 percent, S: less than or equal to 0.005 percent, Alt: 0.020-0.050%, Ca: 0.0010-0.0030%;
(2) the hot rolling production process flow comprises the following steps: heating a casting blank, rough rolling, finish rolling and coiling; the tapping temperature of the casting blank is 1220 +/-20 ℃, the rough rolling is carried out by adopting a 3+3 mode 2-frame rolling mill, the finish rolling is carried out by adopting a 7-frame continuous variable-crown rolling mill, and the thickness of the intermediate blank is 40-45 mm; the finish rolling temperature of finish rolling is 870 +/-20 ℃, and the thickness of the hot rolled steel strip is 3.5 mm; laminar flow cooling equipment is adopted for cooling, a front dispersive cooling mode is adopted, and the coiling temperature is 580 +/-20 ℃;
(3) acid washing cold rolling process flow: pickling the hot-rolled strip steel by using a hydrochloric acid tank of an i-BOX technology, removing surface iron scales, cold-rolling by using a 5-stand cold rolling mill, wherein the cold-rolling reduction rate is 65.7%, and rolling to the target thickness;
(4) the continuous annealing process flow comprises the following steps: uncoiling the cold-hard coil steel strip, heating to 780 +/-10 ℃, soaking for 150-.
6. The production method of the steel for the 280 MPa-grade cold-rolled low yield ratio stamped automobile structure as claimed in claim 1, is characterized by comprising the following steps:
carrying out desulfurization pretreatment on molten iron, carrying out decarburization and dephosphorization on the molten iron by adopting a top-bottom combined blown converter to obtain molten steel, blowing argon in the whole smelting process of the converter, adding scrap steel into the converter, and carrying out tapping temperature of the converter of 1630 ℃; then, carrying out LF external refining on the molten steel smelted by the converter, wherein the refining in-place temperature is more than or equal to 1560 ℃, and carrying out temperature measurement and component fine adjustment by the LF external refining; the superheat degree of the continuous casting of the plate blank is 22 ℃, and then the plate blank is cleaned, slowly cooled and the quality of the continuous casting blank is checked; the heating temperature of the plate blank is 1220 ℃, the heating time is 205min, and the heated plate blank is subjected to high-pressure water dephosphorization; the width is fixed by a width fixing press, 2 frames are adopted for rough rolling, and 7 frames are adopted for CVC finish rolling; the finish rolling temperature is 875 ℃, and the thickness of a finished product is 3.5 mm; the laminar cooling adopts pre-dispersion cooling, and the temperature of the steel strip is reduced to 588 ℃ for coiling; pickling the hot-rolled strip steel by a hydrochloric acid tank, wherein the acid tank adopts an i-BOX technology newly developed by MH, removing surface iron scale of the hot-rolled strip steel, cold-rolling the hot-rolled strip steel by a 5-frame UCM rolling mill, and rolling the cold-rolled strip steel to a target thickness with a cold-rolling reduction rate of 65.7%; the cold-hard coil continuous annealing is carried out in a continuous vertical annealing furnace with HGJC function, the running speed of the steel strip is 100m/min, the soaking temperature is 790 ℃, the soaking time is 170S, the slow cooling temperature is 670 ℃, the fast cooling speed is 30 ℃/S, the overaging temperature is 320 ℃, and the leveling elongation is 0.6%.
7. The production method of the steel for the 280 MPa-grade cold-rolled low yield ratio stamped automobile structure as claimed in claim 1, is characterized by comprising the following steps:
carrying out desulfurization pretreatment on molten iron, carrying out decarburization and dephosphorization on the molten iron by adopting a top-bottom combined blown converter to obtain molten steel, blowing argon in the whole smelting process of the converter, adding scrap steel into the converter, and carrying out tapping at 1648 ℃ by the converter; then, carrying out LF external refining on the molten steel smelted by the converter, wherein the refining in-place temperature is more than or equal to 1560 ℃, and carrying out temperature measurement and component fine adjustment by the LF external refining; the superheat degree of the continuous casting of the plate blank is 23 ℃, and then the plate blank is cleaned, slowly cooled and the quality of the continuous casting blank is checked; heating the plate blank at 1218 ℃ for 202min, and removing phosphorus from the heated plate blank with high-pressure water; the width is fixed by a width fixing press, 2 frames are adopted for rough rolling, and 7 frames are adopted for CVC finish rolling; the finish rolling temperature is 877 ℃, and the thickness of the finished product is 3.5 mm; the laminar cooling adopts pre-dispersion cooling, and the temperature of the steel strip is reduced to 590 ℃ for coiling; pickling the hot-rolled strip steel by a hydrochloric acid tank, wherein the acid tank adopts an i-BOX technology newly developed by MH, removing surface iron scale of the hot-rolled strip steel, cold-rolling the hot-rolled strip steel by a 5-frame UCM rolling mill, and rolling the cold-rolled strip steel to a target thickness with a cold-rolling reduction rate of 65.7%; the cold-hard coil continuous annealing is carried out in a continuous vertical annealing furnace with HGJC function, the running speed of the steel strip is 85m/min, the soaking temperature is 765 ℃, the soaking time is 200S, the slow cooling temperature is 678 ℃, the fast cooling speed is 26 ℃/S, the fast cooling temperature is 318 ℃, and the leveling elongation is 0.6%.
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| CN113528931A (en) * | 2021-05-26 | 2021-10-22 | 唐山钢铁集团高强汽车板有限公司 | Steel strip and production method thereof |
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| CN111363981A (en) * | 2020-03-04 | 2020-07-03 | 包头钢铁（集团）有限责任公司 | 280 MPa-grade cold-rolled low-alloy structural steel and production method thereof |
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| CN113528931A (en) * | 2021-05-26 | 2021-10-22 | 唐山钢铁集团高强汽车板有限公司 | Steel strip and production method thereof |
| CN113528931B (en) * | 2021-05-26 | 2022-06-10 | 唐山钢铁集团高强汽车板有限公司 | Steel strip and production method thereof |
| CN113684419A (en) * | 2021-08-11 | 2021-11-23 | 山东钢铁集团日照有限公司 | Low-cost 400 MPa-grade cold-rolled continuous annealing steel strip and production method thereof |
| CN114015938A (en) * | 2021-10-27 | 2022-02-08 | 包头钢铁（集团）有限责任公司 | 240 MPa-grade cold-rolled carbon structural steel and production method thereof |
| CN115418564A (en) * | 2022-08-18 | 2022-12-02 | 包头钢铁（集团）有限责任公司 | Rare earth treated low-yield-ratio automobile structural steel and production method thereof |
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| CN115612930A (en) * | 2022-10-08 | 2023-01-17 | 包头钢铁（集团）有限责任公司 | Low-roughness steel for automobile seat sliding rail and production method thereof |
| CN115612930B (en) * | 2022-10-08 | 2024-01-19 | 包头钢铁（集团）有限责任公司 | Low-roughness steel for automobile seat slide rail and production method thereof |
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