Preparation method of low-cost high-weldability hot-rolled pickled plate for 440MPa-grade automobile structure

Abstract

The invention relates to a low-cost high-weldability 440MPa-grade hot-rolled pickled plate for an automobile structure and a preparation method of the low-cost high-weldability 440MPa-grade hot-rolled pickled plate. The low-cost high-weldability 440MPa-grade hot-rolled pickled plate comprises the following alloy components: 0.06-0.08% of C, 0.08-0.20% of Si, 1.20-1.40% of Mn, 0.02-0.06% of Alt, less than or equal to 0.015% of P, less than or equal to 0.006% of S, less than or equal to 0.006% of O, less than or equal to 0.005% of N and the balance of Fe and inevitable impurities. The preparation process mainly comprises the steps of blank casting, hot rolling, flattening, acid pickling and the like. According to the method, on the basis of common C and Mn steel, a low-C and low-Mn content design is adopted, a required ferrite pearlite structure is obtained through a hot rolling, controlled rolling and controlled cooling process, grains are refined, the strength is improved, the yield strength of a product is 305-400 MPa, the tensile strength is 440-560 MPa, the ductility is larger than or equal to 33%, the plasticity index and the welding performance are good, and the production cost is lower than that of a common product with the same strength level.

Description

technical field [0001] The invention belongs to the field of material processing, and in particular relates to a preparation method of a hot-rolled pickling plate for automobile structures with low cost and high weldability of 440 MPa. Background technique [0002] High weldability 440MPa hot-rolled pickled sheet for automobile structure belongs to steel for automobile structure, and is used in a large amount in the process of automobile manufacturing. At present, the common 440MPa strength grade hot-rolled pickled sheet is designed with high carbon C: 0.09-0.11%, high manganese Mn: 1.40%-1.60%, which improves the product strength and the alloy cost is high. At the same time, due to the high content of C and the high content of inclusion elements, problems such as inclusion segregation and high yield-strength ratio occur in the production process, which affect the forming and welding performance of the product. [0003] With the maturity of smelting technology and hot rolli...

AI Technical Summary

Problems solved by technology

At present, the hot-rolled pickling plate with a strength level of 440MPa is designed with high-carbon C: 0.09-0.11%, high-manganese Mn: 1.40%-1.60%, which improves product strength and high alloy cost.

At the same time, due to the high content of C and the high content of inclusion elements, problems such as segregation of inclusions and high yield ratio will occur during the production process, which will affect the forming and welding performance of the product.

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