450 MPa-level zinc-plated dual-phase steel for sedan and production method thereof

Abstract

450 MPa-level zinc-plated dual-phase steel for a sedan comprises components in percentage by weight as follows: 0.04%-0.09% of C, smaller than or equal to 0.01% of Si, 1.0%-2.0% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.010% of S, 0.01%-0.08% of Als, 0.01%-0.30% of Mo, 0.01%-1.0% of Cr, 0.001%-0.03% of Nb and smaller than or equal to 0.005% of N. The production steps comprise heating of a casting blank after smelting, refining and continuous casting; finish rolling; reeling; cold rolling after acid pickling; hot galvanizing; finishing. The mechanical properties of a product are shown as follows: the yield strength is 260-320 MPa, the tensile strength is 470-510 MPa, the elongation percentage is 28%-33%, and the n value is 0.17-0.19; the product has good platability, the surface of a plating has uniform glossiness and doesn't have defects, an inhibition layer is continuous and compact, the adhesion of the zinc-plated layer reaches the first level of ball impacting, the bending test proves that the zinc-plated layer and base steel are qualified, and surface quality requirements of an intermediate car for a high-strength structural part and an outer covering part can be met.

Description

technical field [0001] The invention relates to a galvanized steel for automobiles and a method thereof, in particular to a galvanized dual-phase steel for 450MPa class cars and a production method thereof. Background technique [0002] With the continuous development of automobile lightweight and the continuous improvement of occupant safety requirements, the proportion and amount of high-strength steel in automobile body-in-white have increased rapidly in recent years. Due to its high strength, low yield ratio and good forming It is more and more favored by the automobile industry, and the proportion of applications in automobiles is constantly increasing. Compared with cold-rolled dual-phase steel, galvanized dual-phase steel also has excellent anti-corrosion performance, which can ensure that automobiles have good corrosion resistance and perforation ability. Zinc duplex steel can also be used in car panels. Under the premise of ensuring the mechanical properties of hi...

AI Technical Summary

Problems solved by technology

[0003] After searching, the Chinese patent application number is 201220277421.X, which discloses "a cold-rolled dual-phase steel plate with a tensile strength of 450MPa and its manufacturing method", which is produced by the C-Si-Mn-Cr composition system. A 450MPa grade cold-rolled dual-phase steel was developed. Since Si is easily enriched on the surface during annealing, it is not suitable for the production of galvanized dual-phase steel with high surface quality.

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