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

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 is larger than or equal to 2.3, the work-hardening exponent n is larger than or equal to 0.25, and the extending rate A80 mm is larger than or equal to 44 percent.