A rolling method of a b280vk automobile structural steel

Abstract

The application belongs to the technical field of steel metallurgy, and particularly discloses a rolling method of B280VK automobile structure steel, which comprises the following steps: first, limiting the proportion of key components: C 0.10%-0.14%, Mn 1.10%-1.30%, and Si 0.18%-0.30%; and then, performing five processes of hot rolling, cold rolling, cover annealing, flattening and heavy rolling; controlling the slab heating, final rolling and thickness separation coiling temperature in the process of hot rolling; dynamically adjusting the reduction rate according to the strength of the hot rolling raw material; stabilizing the heating rate and standardizing the cooling process in the cover annealing; and setting the elongation rate according to the thickness and controlling the oiling amount in the flattening and heavy rolling. The application can solve the problems of mechanical property fluctuation, many surface defects and low product qualification rate in the production of automobile structure steel. Through the linkage optimization of component narrowing and whole-process parameters, the application can stabilize the mechanical property, improve the product qualification rate and produce cold rolled high-strength steel meeting the use requirements of automobile structure parts.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, specifically to a rolling method for B280VK automotive structural steel. Background Technology

[0002] B280VK is a cold-rolled high-strength steel widely used in automotive structural parts. Its surface quality and the stability of its mechanical properties directly affect the safety and forming quality of downstream automotive components. In actual production, B280VK steel suffers from prominent problems such as low tensile strength, unsuitable elongation, surface quality defects (e.g., rust, scratches, pits, surface blackening), and severe losses due to folding marks within the original coil. These issues have resulted in a product qualification rate consistently below 90%, seriously impacting production efficiency and customer satisfaction.

[0003] Analysis revealed that the cause involved multiple processes, including hot rolling, cold rolling, annealing, leveling, and chemical composition control. In existing technologies, the process parameters for each process are often set based on empirical values, lacking a systematic linkage optimization mechanism. Furthermore, the annealing process is severely affected by the furnace charge, and the heating rate is uncontrollable, resulting in large fluctuations in the cleanliness and mechanical properties of the strip steel. Summary of the Invention

[0004] The purpose of this invention is to provide a rolling method for B280VK automotive structural steel, in order to solve the problem that the existing finished product qualification rate optimization methods in the production process of B280VK steel are based on empirical values ​​and lack a systematic linkage optimization mechanism.

[0005] To achieve the above objectives, the basic solution provided by this invention is as follows: a rolling method for B280VK automotive structural steel, wherein the chemical composition of the automotive structural steel, by weight percentage, includes: C content 0.10%–0.14%, Mn content 1.10%–1.30%, Si content 0.18%–0.30%, Al content 0.2%–0.40%, P content ≤0.018%, S content ≤0.004%, and N content ≤0.006%; and further includes the following steps: S1. Hot rolling process: The temperature of the heating and soaking zone is 1150~1210℃, the total time in the furnace is ≥210min, the soaking zone time is ≥40min before steel can be tapped, the temperature difference between the head and tail of the slab is less than 20℃, the final rolling temperature is 870±15℃, the temperature of F1~F4 rolls is ≤75℃, the temperature of F5~F6 rolls is ≤60℃, the cooling mode is low-pressure intensive cooling, and the coiling temperature is controlled according to the thickness of the strip. S2, Cold rolling process: When the tensile strength of hot-rolled raw material is lower than 460MPa, increase the cold rolling reduction rate by 10-30% to increase the work hardening reserve, control the surface reflectivity of the plate to ≥60%, F1~F4 mills use large bending rolls, the bending roll force is controlled according to the strip thickness, and the intermediate roll is reduced by 40~50mm from the set value. S3. Annealing Process: A bell-type annealing process is used. At least six heating burners must be in operation. The annealing temperature is controlled at 600℃±10℃, held for 2 hours. After the material chamber temperature reaches 430℃, the heating rate is controlled at 30~40℃ / h. The heating time is controlled according to the strip thickness. After heating, the cooling hood must be replaced within 15 minutes. Two axial flow cooling fans provide a cooling airflow of 17000 m³ / h. 3 / h / unit, water cooling begins when the material chamber temperature reaches 380℃, and the cooling water consumption must be greater than 25m³. 3 / h, the furnace temperature is controlled at 100℃±5℃; S4. Leveling process: Production is carried out according to the elongation rate model, and the elongation rate is controlled according to the strip thickness. S5. Rewinding process: The tension leveler is controlled according to the elongation mode.

[0006] The beneficial effects of this invention are as follows: by narrowing the composition range of key elements such as C, Mn, and Si, the fundamental mechanical properties are guaranteed from the metallurgical source, fundamentally improving the problem of low tensile strength; by adding a 430℃ holding platform for 2 hours in the annealing process, the problem of uncontrollable heating rate caused by the furnace charge in the annealing process is solved, allowing the emulsion on the strip surface to fully evaporate, improving the cleanliness of the strip surface, and at the same time, the heating rate is stably controlled within 35℃ / h; in addition, through the linkage optimization of parameters of each process of hot rolling, cold rolling, annealing, and leveling, especially the dynamic adjustment of cold rolling reduction rate and leveling elongation rate, the qualification rate of B280VK steel grade is increased from less than 90% to more than 99.5%.

[0007] Option 2 is the preferred option of the basic option. In S1, the convexity is ≤40µm and |wedge| < |convexity|.

[0008] Option 3, which is the preferred option of the basic option, in S1, the winding temperature is controlled according to the strip thickness as follows: when the strip thickness is 2.0~3.0mm, the winding temperature is 590℃±15℃, and when the strip thickness is 3.01~5.0mm, the winding temperature is 560℃±15℃.

[0009] Option 4 is the preferred option of the basic option. In S2, the bending roll force is controlled according to the strip thickness as follows: when the strip width is <1200mm, the bending roll force of the large bending roll of the F1~F4 rolling mill is 450~550KN; when the strip width is ≥1200mm, the bending roll force of the large bending roll of the F1~F4 rolling mill is 200~450KN.

[0010] Option 5, which is the preferred option of the basic option, in S3, the heating time is controlled according to the strip thickness as follows: when the strip thickness is <1.6mm, the heating time is 10~11h and the high temperature holding time is 8~8.5h; when the strip thickness is ≥1.6mm, the heating time is 10~12h and the holding time is 8.5~9.5h.

[0011] Option 6, the preferred option of the basic option, in S4, the elongation is controlled according to the strip thickness as follows: When the strip thickness is 0.3~0.499mm, the elongation is controlled to be 0.6~0.8%; When the strip thickness is 0.5~0.699mm, the elongation is controlled to be 0.7~0.9%; When the strip thickness is 0.7~0.899mm, the elongation is controlled to be 0.9~1.1%; When the strip thickness is 0.9~1.099mm, the elongation is controlled to 1.0~1.2%; When the strip thickness is 1.1~1.499mm, the elongation is controlled to 1.3~1.5%; When the strip thickness is 1.5~1.699mm, the elongation is controlled to 1.5~1.7%; When the strip thickness is 1.7~1.999mm, the elongation is controlled to 1.7~1.9%; When the strip thickness is ≥2.0mm, the elongation should be controlled to 1.9~2.1%.

[0012] Option 7, the preferred option of the basic option, in S5, the elongation rate is controlled by the tension leveler as follows: when the strip thickness is 0.3~0.899mm, the elongation rate is controlled to 0.6~0.8%; when the strip thickness is 0.9~2.5mm, the elongation rate is controlled to 0.3~0.4%. The surface oiling amount is 1.1~1.5g / m. 2 To take control. Detailed Implementation

[0013] The present invention will be further described in detail below through specific embodiments: Example 1

[0014] The process route of this invention is as follows: hot metal desulfurization treatment → 120t converter → LF furnace → slab continuous casting → 1750 heating → 1750mm rolling → laminar flow cooling → cold rolling pickling → cold rolling mill → cold rolling annealing → cold rolling leveling → cold rolling recoiling.

[0015] A rolling method for B280VK automotive structural steel, wherein the chemical composition of the automotive structural steel, by weight percentage, includes: C content 0.10%–0.14%, Mn content 1.10%–1.30%, Si content 0.18%–0.30%, Al content 0.2%–0.40%, P content ≤0.018%, S content ≤0.004%, and N content ≤0.006%; and further includes the following steps: S1. Hot rolling process: The heating and soaking zone temperature is 1150~1210℃, the total furnace time is ≥210min, the soaking zone time is ≥40min before steel can be tapped, the temperature difference between the head and tail of the slab is less than 20℃, the final rolling temperature is 870±15℃, the F1~F4 roll temperature is ≤75℃, the F5~F6 roll temperature is ≤60℃, the crown is ≤40µm, |wedge| < |crown|, the cooling mode is low-pressure intensive cooling, and the coiling temperature is controlled according to the strip thickness. The control method for the coiling temperature according to the strip thickness is as follows: when the strip thickness is 2.0~3.0mm, the coiling temperature is 590℃±15℃, and when the strip thickness is 3.01~5.0mm, the coiling temperature is 560℃±15℃. S2. Cold rolling process: When the tensile strength of the hot-rolled raw material is lower than 460MPa, increase the cold rolling reduction rate by 10-30% to increase the work hardening reserve, control the surface reflectivity of the plate to ≥60%, and use large bending rolls in F1~F4 mills. The bending roll force is controlled according to the strip thickness. The control method for the bending roll force according to the strip thickness is as follows: when the strip width is <1200mm, the bending roll force of the large bending roll in F1~F4 mills is 450~550KN; when the strip width is ≥1200mm, the bending roll force of the large bending roll in F1~F4 mills is 200~450KN. The intermediate roll is reduced by 40~50mm from the set value. S3. Annealing Process: A bell-type annealing process is used. At least six heating burners must be in operation. The annealing temperature is controlled at 600℃±10℃, with a holding time of 2 hours. After the material chamber temperature reaches 430℃, the heating rate is controlled at 30~40℃ / h. The heating time is controlled according to the strip thickness: when the strip thickness is <1.6mm, the heating time is 10~11 hours, with a high-temperature holding time of 8~8.5 hours; when the strip thickness is ≥1.6mm, the heating time is 10~12 hours, with a holding time of 8.5~9.5 hours. After heating, the cooling hood must be replaced within 15 minutes. Two axial flow cooling fans provide a cooling airflow of 17000 m³ / h. 3 / h / unit, water cooling begins when the material chamber temperature reaches 380℃, and the cooling water consumption must be greater than 25m³. 3 / h, the furnace temperature is controlled at 100℃±5℃; S4. Leveling Process: Production is carried out according to the elongation rate model. The elongation rate is controlled according to the strip thickness. The control method for the elongation rate based on the strip thickness is as follows: when the strip thickness is 0.3~0.499mm, the elongation rate is controlled to 0.6~0.8%; when the strip thickness is 0.5~0.699mm, the elongation rate is controlled to 0.7~0.9%; when the strip thickness is 0.7~0.899mm, the elongation rate is controlled to 0.9~1.1%; when the strip thickness is... For strip thicknesses of 0.9~1.099mm, the elongation should be controlled at 1.0~1.2%; for strip thicknesses of 1.1~1.499mm, the elongation should be controlled at 1.3~1.5%; for strip thicknesses of 1.5~1.699mm, the elongation should be controlled at 1.5~1.7%; for strip thicknesses of 1.7~1.999mm, the elongation should be controlled at 1.7~1.9%; and for strip thicknesses ≥2.0mm, the elongation should be controlled at 1.9~2.1%. S5. Rewinding Process: The tension leveler is controlled according to the elongation mode. The elongation is controlled as follows: when the strip thickness is 0.3~0.899mm, the elongation is controlled to 0.6~0.8%; when the strip thickness is 0.9~2.5mm, the elongation is controlled to 0.3~0.4%. The surface oiling amount is 1.1~1.5g / m. 2 To take control.

[0016] Example 2

[0017] A rolling method for B280VK automotive structural steel, with controlled chemical composition: C content controlled at 0.13%, Mn content controlled at 1.15%, Si content controlled at 0.20%, Al content controlled at 0.30%, P content controlled at 0.015%, S content controlled at 0.002%, and N content controlled at 0.005%. In the hot rolling process, the final rolling temperature is controlled at 860℃, the coiling temperature at 590℃, and the temperature difference between the slab head and tail controlled at 18℃. In the cold rolling process, when the tensile strength of the hot-rolled raw material is 455MPa, the cold rolling reduction rate is increased to 72%. In the annealing process, a bell-type annealing method is used, with an annealing temperature of 600℃, a holding platform at 430℃ for 2 hours, a heating rate controlled at 35℃ / h after 430℃, a holding time of 8 hours, and a furnace exit temperature of 100℃. In the leveling process, for a thickness of 1.5mm, an elongation model is used, with a target leveling rate of 1.6%.

[0018] Testing showed that the B280VK steel produced in this embodiment has a tensile strength of 482MPa, a yield strength of 352MPa, and an elongation of 28%. All indicators meet the standard requirements, and the pass rate reaches 99.85%.

[0019] Example 3

[0020] A rolling method for B280VK automotive structural steel. The difference between this embodiment and Embodiment 2 is that the tensile strength of the hot-rolled raw material is 470MPa, the cold rolling reduction rate is adjusted to 68%, the thickness is 2.0mm, the flatness target value is 2.0%, and the annealing holding time is 8.5h.

[0021] Testing showed that the B280VK steel produced in this embodiment had a tensile strength of 478 MPa, a yield strength of 348 MPa, an elongation of 29%, and a pass rate of 99.68%.

[0022] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A rolling method for B280VK automotive structural steel, characterized in that, The chemical composition of automotive structural steel, by weight percentage, includes: C content 0.10%–0.14%, Mn content 1.10%–1.30%, Si content 0.18%–0.30%, Al content 0.2%–0.40%, P content ≤0.018%, S content ≤0.004%, and N content ≤0.006%; it also includes the following steps: S1. Hot rolling process: The temperature of the heating and soaking zone is 1150~1210℃, the total time in the furnace is ≥210min, the soaking zone time is ≥40min before steel can be tapped, the temperature difference between the head and tail of the slab is less than 20℃, the final rolling temperature is 870±15℃, the temperature of F1~F4 rolls is ≤75℃, the temperature of F5~F6 rolls is ≤60℃, the cooling mode is low-pressure intensive cooling, and the coiling temperature is controlled according to the thickness of the strip. S2, Cold rolling process: When the tensile strength of hot-rolled raw material is lower than 460MPa, increase the cold rolling reduction rate by 10-30% to increase the work hardening reserve, control the surface reflectivity of the plate to ≥60%, F1~F4 mills use large bending rolls, the bending roll force is controlled according to the strip thickness, and the intermediate roll is reduced by 40~50mm from the set value. S3. Annealing Process: A bell-type annealing process is used. At least six heating burners must be in operation. The annealing temperature is controlled at 600℃±10℃, held for 2 hours. After the material chamber temperature reaches 430℃, the heating rate is controlled at 30~40℃ / h. The heating time is controlled according to the strip thickness. After heating, the cooling hood must be replaced within 15 minutes. Two axial flow cooling fans provide a cooling airflow of 17000 m³ / h. 3 / h / unit, water cooling begins when the material chamber temperature reaches 380℃, and the cooling water consumption must be greater than 25m³. 3 / h, the furnace temperature is controlled at 100℃±5℃; S4. Leveling process: Production is carried out according to the elongation rate model, and the elongation rate is controlled according to the strip thickness. S5. Rewinding process: The tension leveler is controlled according to the elongation mode.

2. The rolling method for B280VK automotive structural steel according to claim 1, characterized in that, In S1, the convexity is ≤40µm, and |wedge| < |convexity|.

3. The rolling method for B280VK automotive structural steel according to claim 1, characterized in that, In S1, the coiling temperature is controlled according to the strip thickness as follows: when the strip thickness is 2.0~3.0mm, the coiling temperature is 590℃±15℃; when the strip thickness is 3.01~5.0mm, the coiling temperature is 560℃±15℃.

4. The rolling method for B280VK automotive structural steel according to claim 1, characterized in that, In S2, the bending roll force is controlled according to the strip thickness as follows: when the strip width is <1200mm, the bending roll force of the large bending roll of the F1~F4 mill is 450~550KN; when the strip width is ≥1200mm, the bending roll force of the large bending roll of the F1~F4 mill is 200~450KN.

5. The rolling method for B280VK automotive structural steel according to claim 1, characterized in that, In S3, the heating time is controlled according to the strip thickness as follows: when the strip thickness is <1.6mm, the heating time is 10~11h and the high temperature holding time is 8~8.5h; when the strip thickness is ≥1.6mm, the heating time is 10~12h and the holding time is 8.5~9.5h.

6. The rolling method for B280VK automotive structural steel according to claim 1, characterized in that, In S4, the elongation rate is controlled according to the strip thickness as follows: When the strip thickness is 0.3~0.499mm, the elongation is controlled to be 0.6~0.8%; When the strip thickness is 0.5~0.699mm, the elongation is controlled to be 0.7~0.9%; When the strip thickness is 0.7~0.899mm, the elongation is controlled to be 0.9~1.1%; When the strip thickness is 0.9~1.099mm, the elongation is controlled to 1.0~1.2%; When the strip thickness is 1.1~1.499mm, the elongation is controlled to 1.3~1.5%; When the strip thickness is 1.5~1.699mm, the elongation is controlled to 1.5~1.7%; When the strip thickness is 1.7~1.999mm, the elongation is controlled to 1.7~1.9%; When the strip thickness is ≥2.0mm, the elongation should be controlled to 1.9~2.1%.

7. The rolling method for B280VK automotive structural steel according to claim 1, characterized in that, In S5, the elongation is controlled by the tension leveler as follows: when the strip thickness is 0.3~0.899mm, the elongation is controlled to 0.6~0.8%; when the strip thickness is 0.9~2.5mm, the elongation is controlled to 0.3~0.4%. The surface oiling amount is 1.1~1.5g / m. 2 To take control.