MANUFACTURE OF COLD ROLLED STEEL SHEET WITH SUPERIOR DRAWABILITY

摘要

PURPOSE:To manufacture economically a cold rolled steel sheet with superior drawability by continuously casting a steel having a specified composition, subjecting the resulting billet to hot rolling, pickling and cold rolling, and carrying out continuous annealing at a specified temp. CONSTITUTION:A molten steel consisting of, by weight, 0.006-0.025% C, <=0.03% Si, 0.06-0.30% Mn, <=0.025% P, <=0.025% S, <=0.007% sol.Al, <=0.0030% N, <=90ppm free oxygen and the balance Fe with inevitable impurities is continuously cast. The resulting billet is continuously hot rolled, pickled, and cold rolled, and soaking at a temp. from the recrystallization temp. to the Ac3 point for >=about 10sec, optional slow cooling at >=about 20 deg.C/sec cooling rate, and rapid cooling at >=about 50 deg.C/sec cooling rate are carried out.