High tensile strength substrate, hot dip galvanizing automobile exterior panel and manufacturing method thereof

Abstract

The invention relates to a high tensile strength base plate, the chemical compositions (weight percent) of which are: C: 0.01 to 0.08 percent, Si: less than or equal to 0.1 percent, Mn: 0.8 to 1.8 percent, Cr: less than or equal to 1.0 percent, Mo: less than or equal to 0.5 percent, TAl: 0.02 to 0.08 percent, N: less than or equal to 0.006 percent, P+2S: less than or equal to 0.12 percent, Mn+3Cr+2Mo: more than or equal to 1.6 percent and less than or equal to 3.8 percent, and the rest is Fe. A high tensile strength hot galvanizing automobile outside plate adopting the high tensile strength base plate and a preparation method thereof comprise the following steps of: casting the components into blank plates by smelting, refining and continuous casting; hot rolling which adopts high temperature curling at 650 to 680 DEG C to obtain normal pearlite and ferrite original tissue, and then continuous casting with normal cool acid; hot galvanizing annealing with the critical re-crystallization annealing temperature at 800 to 860 DEG C; the cooling speed from the annealing temperature to a zinc pool is 5 to 16 DEG C / s; and entering into the zinc pool with the temperature of 450 to 465 DEG C and finishing galvanization treatment.

Description

technical field [0001] The invention relates to the field of metal materials, in particular to a substrate with high tensile strength, a hot-dip galvanized automobile outer panel and a manufacturing method thereof. Background technique [0002] In the past few decades, as the steel for automobile outer panels, in order to comply with the development trend of deep drawing, weight reduction, and anti-denting, it has undergone several important changes and developments. Initially, mild steel was mainly used, including low-carbon aluminum-killed steel and deep-drawing IF steel. IF steel has excellent cold forming properties and its low alloying elements ensure that the steel plate has excellent surface quality after galvanizing, but its strength is low. As a result, the dent resistance of the steel plate is poor. As a compensation, in recent years, a large number of bake-hardened steels have been used as outer plates. Bake-hardened steel (BH steel) is a kind of micro-alloy high...

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Problems solved by technology

[0007] At present, the outer panels of cars are mainly made of interstitial-free steel (IF steel) of mild steel and bake-hardening steel (BH) of high-strength steel. IF steel has insufficient dent resistance, while BH steel of 340MPa has good dent resistance. permanent but time-sensitive limitations

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