600 MPa grade galvanized dual-phase steel for saloon car and production method of 600 MPa grade galvanized dual-phase steel

Abstract

A 600 MPa grade galvanized dual-phase steel for a saloon car comprises the following ingredients in percent by weight: 0.04-0.09 percent of C, less than or equal to 0.01 percent of Si, 1.0-2.5 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.010 percent of S, 0.01-0.08 percent of Als, 0.01-0.30 percent of Mo, 0.02-0.09 percent of Cr, 0.001-0.03 percent of Nb, and less than or equal to 0.005 percent of N. The production method comprises the following production steps: heating a casting blank after smelting, refining and continuous casting; conducting finish rolling on the casting blank; coiling; conducting cold rolling after pickling; conducting hot galvanizing; and finishing. The mechanical properties of the 600 MPa grade galvanized dual-phase steel meet the requirements that the yield strength is 340-400 MPa, the tensile strength is 610-650 MPa, the elongation is 21%-25%, and n ranges from 0.14 to 0.170. The 600 MPa grade galvanized dual-phase steel is high in platability, the surface of a clad layer is uniform in color and zero-defect, an inhibition layer is continuous and compact, the adhesive force of a galvanized layer reaches the first-class spherical punching level, the galvanized layer and steel bending test is up to the standard. The 600 MPa grade galvanized dual-phase steel can meet the requirement, on the surface quality of a high-strength structural part and an outer cover part, of an intermediate car.

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 600MPa 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 retrieval, Chinese patent application numbers 201210119633.5 and 201210284401.5 respectively disclose "a 600MPa low process sensitivity cold-rolled dual-phase steel and its production method" and "a 600MPa aluminum-based hot-dip galvanized dual-phase steel". Steel Plate and Its Preparation", both of which use the C-Mn-Al-Mo composition system to produce low process sensitivity 600MPa cold-rolled dual-phase steel and galvanized dual-phase steel, although the addition of Si or Al can significantly improve the annealing of the steel Process sensitivity, but Si and Al elements will be enriched on the surface during annealing, so it is not suitable for the production of galvanized dual-phase steel with high surface quality

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