Galvanized dual-phase steel for 500 MPa class car and production method

Abstract

A galvanized dual-phase steel for a 500 MPa class car comprises the following components in percentage by weight: 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 or 0.02-0.9% of Cr, 0.001-0.03% of Nb and smaller than or equal to 0.005% of N. The production method comprises the following production steps: heating of casting blanks after smelting, refining and continuous casting, finish rolling, reeling, cold rolling after acid pickling, hot galvanizing, and finishing. According to the mechanical properties of the product, yield strength is 295-365 MPa, tensile strength is 515-558 MPa, ductility is 25-30%, and n value is 0.165-0.18; and platability of the product is good, the surface of a plating layer is uniform in color and does not have defects, an inhibition layer is continuous and compact, the adhesive force of a zinc layer reaches level-one standard of ball punching, bending test on the zinc layer and a steel base is qualified, and requirements of intermediate cars on surface quality of high-strength structures and outer covering parts 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 a 500MPa class car 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 h...

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Problems solved by technology

[0003] After searching, the Chinese patent application number is 201410536158.0, which discloses "500MPa-grade cold-rolled dual-phase steel and its production method", and a 500MPa-grade cold-rolled dual-phase steel is produced by using the C-Si-Mn-B composition system. Steel, due to the easy enrichment of Si element 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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