Cold-rolled high strength steel sheet prodn. - by hot rolling, cold rolling, and tempering in temperature range of 620 degrees Celsius to A3 point

摘要

A cold-rolled high strength steel sheet with good cold workability has the compsn. (wt. %) 0.03-0.2C, 0.6-1.5 Si, 1.3-3.0 Mn, 0.01-0.25 Nb, or 0.01-0.i Ti or 0.01-0.3 Nb + Ti, balance Fe and usual impurities. The sheet is produced by hot and cold rolling and by tempering at a temp. range 620 degrees to the A3 pt. A prefd. compsn. comprises 0.03-0.2 wt. %C, 1.0:1.5 wt. % Si, 1.3-2.0 wt. % Mn, 0.01-0.25 wt. % Nb, or 0.01-0.2 wt.% Ti, or 0.01-0.3 wt.% Nb + Ti, balance Fe and impurities. The steel is partic. suitable for automobile bodies.