| 摘要 |
PURPOSE:To produce a cold-rolled steel plate having high drawability in a process for producing thin billets from molten steel by limiting the compsn. of the molten steel and performing cooling, rolling, and continuous annealing of the billet under specified conditions. CONSTITUTION:Molten steel consisting by wt% of <=0.02 C, <=1.00 Mn, contg. further 0.002-0.100 at least one among Al, Ti, Nb, and B alone or in total, if necessary, is formed to a thin thickness continuously casted steel strip through a strip caster. The billet is cooled primarily immediately after casting to a temp. range from above the Ar3 transformation point (T) upto T+20 deg.C with <=20 deg.C/ min mean cooling rate V1. The billet is succedingly cooled secondarily to below T with >=5 deg.C/min mean cooling rate V2. The billet is rolled with 60-95% draft at a temp. below the recrystallization temp., and the rolled steel plate is annealed continuously at below T annealing temp. with >=100 deg.C/min heating rate. |
