Steel with extending rate larger than or equal to 44 percent for electrogalvanizing automobile outer plate and production method

Abstract

Disclosed is steel with the extending rate larger than or equal to 44 percent for an electrogalvanizing automobile outer plate. The steel comprises, by weight, C smaller than or equal to 0.0018 percent, Si smaller than or equal to 0.015 percent, Mn ranging from 0.05 percent to 0.18 percent, P smaller than or equal to 0.015 percent, S smaller than or equal to 0.010 percent, Ti ranging from 0.02 percent to 0.03 percent, Nb ranging from 0.03 percent to 0.05 percent, Als ranging from 0.02 percent to 0.05 percent and N smaller than or equal to 0.003 percent. The production steps comprise smelting and continuous casting to form a billet, hot rolling, reeling, cold rolling, continuous annealing and cooling. The method comprises the steps of slow cooling and then rapid cooling, finishing, alkaline washing, brushing, electrolytic degreasing and rinsing, and electrogalvanizing through a gravitational method. The steel has the advantages of being good in surface quality, stable in performance, free of aging, excellent in forming performance, excellent in welding performance and the like; according to the material object performance (perpendicular to the rolling direction) of a finished electrogalvanizing super-deep punching board DC07+ZE for the automobile outer plate, the yield strength is 100 MPa to 150 MPa, the tensile strength is 250 MPa to 310 MPa, the plastic strain ratio r<90> is larger than or equal to 2.3, the work-hardening exponent n<90> is larger than or equal to 0.25, and the extending rate A80 mm is larger than or equal to 44 percent.

Description

technical field [0001] The invention relates to a cold-rolled deep-drawing electro-galvanized automobile steel and a production method thereof, in particular to an electro-galvanized automobile outer plate steel with an elongation ≥ 44% and a production method thereof. Background technique [0002] Since the automobile manufacturing industry has very high requirements on the outer plate, the steel plate is required to have ultra-high stamping performance and excellent surface quality. [0003] At present, most domestic and foreign automobile manufacturers use hot-dip galvanized deep-drawing plates, that is, the steel plates after continuous annealing enter the zinc pot, and the excess zinc liquid on the surface is blown off by an air knife. Its surface quality is difficult to control stably. When the automobile factory uses it, the protruding zinc slag on the surface of the steel plate is likely to form nodules in the stamping die and affect subsequent stamping; [0004] At...

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Problems solved by technology

Its surface quality is difficult to control stably. When the automobile factory uses it, the protruding zinc slag on the surface of the steel plate is easy to form nodules in the stamping die and affect the subsequent stamping; in the painting process, the defects on the steel plate surface are easy to be enlarged and affect the appearance of the car body.

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