Continuous annealing production method for steel for 280 MPa vehicle structure

Abstract

The invention relates to a continuous annealing production method for steel for a 280 MPa vehicle structure, belonging to the technical field of the production of metallurgical plates. The technical scheme comprises smelting, hot rolling, cold rolling and continuous annealing processes. The final chemical composition comprises the following components in percentage by mass: 0.145% to 0.185% of C, 0.05% to 0.15% of Si, 0.55% to 0.65% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 0.013% to 0.023% of Als, less than or equal to 0.004% of N, and Fe in balancing amount. In the smelting process, the blowing endpoint of a converter requires that: C is less than or equal to 0.10%, P is less than 0.015% and S is less than or equal to 0.035%. According to the continuous annealing production method, no microalloy element is added; the C content is increased by controlling the steel-making process so as to improve the yield strength and reduce the content of Si, Mn and P; the steel-making, hot rolling, cold rolling and continuous annealing processes are improved to produce the steel for the vehicle structure having a yield strength more than 280 MPa and an elongation of more than 30%; the obdurability is matched well; the cost is low; and the mechanical performance index of the finished product is as follows: the yield strength is about 300 MPa, the tensile strength is about 430 MPa, and the elongation is more than or equal to 30%.

Description

technical field [0001] The invention relates to a continuous annealing production method of 280MPa grade automobile structural steel, which belongs to the technical field of metallurgical plate production. Background technique [0002] At present, the main grades of 280MPa grade automotive structural steel are CR260IF, B280VK, CR260 / 450DP, etc. The characteristics of these grades of steel are that it is difficult to smelt and more alloys are added, resulting in higher production costs. First of all, CR260IF is a high-strength phosphorus-containing IF steel. IF steel requires low carbon content and high smelting costs. The strength is improved by adding non-metallic elements such as Si and P. Secondly, B280VK uses a low-carbon aluminum-killed steel composition system, and the strength is improved by adding Mn, P, etc., while the price of Mn alloy is relatively high, thereby increasing the cost. Third, CR260 / 450DP is a dual-phase steel. It mainly improves the stability of au...

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Problems solved by technology

Secondly, B280VK uses a low-carbon aluminum-killed steel composition system, and the strength is improved by adding Mn, P, etc., while the price of Mn alloy is relatively high, thereby increasing the cost

Third, CR260 / 450DP is a dual-phase steel. It mainly improves the stability of austenite by adding elements such as C, Mn, and Si, thereby increasing the martensitic transformation temperature, thereby realizing industrial production of dual-phase steel. Due to C, Mn, and Si High element content, high requirements for equipment, high production cost

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