A New Type of Dual-phase Steel Sheet for Automobile Outer Body Panels

A new type of cold rolled dual phase steel sheet with good formability and dent-resistance has been developed for automobile outer body panels. The steel, basically a low carbon and manganese aluminum killed steel, is manufactured by means of hot rolling with high temperature coiling, cold rolling, and continuous annealing with water-quenching and tempering. The mechanical properties after temper rolling are characterized by yield strength lower than 24kgf/mm2, total elongation larger than 40% and r-value higher than 1.5. Moreover the steel sheet has not only high bake hardenability but also high anti-aging property.