600MPa-level ultra-low silicon cold rolling hot galvanizing dual-phase steel and preparation process thereof

Abstract

The invention discloses 600MPa-level ultra-low silicon cold rolling hot galvanizing dual-phase steel and a preparation process. The dual-phase steel contains the following chemical components in the weight percentage (wt.%): 0.03-0.16 percent of C, less than 0.02 percent of Si, 1.2-2.2 percent of Mn, 0.2-0.6 percent of Cr, less than 0.015 percent of S, less than 0.020 percent of P, 0.01-0.08 percent of Als and the balance of Fe. The preparation process comprises the following steps of: (1) smelting the chemical compositions in a claim 1 to obtain a cast slab; (2) carrying out heating and hot rolling on the cast slab to obtain a hot-rolled plate; (3) carrying out acid washing and then cold rolling on the hot-rolled plate to manufacture a cold-rolled sheet, wherein the cold rolling down rate is 45-80 percent; and (4) carrying out hot galvanizing annealing on the cold-rolled sheet to prepare a finished steel plate. The dual-phase steel has the characteristics of high strength, low cost, low carbon equivalent, ultra-low silicon and good surface quality and is suitable for automobile steel.

Description

Technical field [0001] The invention relates to a 600MPa grade ultra-low silicon cold-rolled hot-dip galvanized dual-phase steel and a preparation process thereof, in particular to a cold-rolled dual-phase steel with a Si content of less than 0.02wt% in the steel and a preparation process thereof, belonging to the cold-rolled high The technical field of steel sheets for high-strength automobiles. Background technique [0002] In recent years, as energy, resource, and environmental problems have become increasingly serious, it has become an inevitable trend for automobiles to reduce weight, reduce weight and save energy, and reduce emissions. In terms of automotive steel, a large number of high-strength and ultra-high-strength steel plates have become the direction of the joint efforts of modern automobile manufacturers and steel manufacturers, so as to continuously research and develop different strength levels of dual-phase steel (DP steel), TRIP steel, etc. The application of ...

AI Technical Summary

Problems solved by technology

Therefore, at present, the Si content of hot-dip galvanized dual-phase steel at home and abroad is usually between 0.02 and 0.15%, in order to take advantage of the favorable factors of Si. However, high Si content will form thicker oxide scale and red rust, which will directly deteriorate The surface quality and coating performance of the steel plate should be paid special attention to the hot-dip galvanized steel plate

At the same time, since the coating quality and zinc layer adhesion of the hot-dip galvanized sheet decrease with the increase of the silicon content in the substrate, it affects the coating performance, formability and welding performance of the hot-dip galvanized sheet

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