Production manner null of the cold rolling steel sheet for super deep drawing where surface quality

摘要

PURPOSE: To produce a cold rolled steel sheet for extra deep drawing, excellent in surface quality. ;CONSTITUTION: A cast slab, having a composition containing, by weight, 0.0005-0.0025% C, ≤0.30% Si, 0.01-0.08%, preferably 0.01-0.05%, Mn, ≤0.030% P, ≤0.005% S, 0.015-0.100% sol.Al, 0.0005-0.0100% N, and 0.020-0.080% Ti, is heated to 1130-1240°C, finish-rolled at a temp. not lower than the Ar₃ point, and coiled at 700-800°C, The resultant hot rolled steel strip is cold-rolled and then heated to a temp. between the recrystallization temp. and 890°C by a continuous annealing method and recrystallization-annealed, by which an annealed sheet is prepared. By temper-rolling this steel sheet at 0.3-2.0%, the cold rolled steel sheet for extra deep drawing, excellent in surface quality, can be obtained. Further, superior secondary workability can be provided by adding 0.0002-0.0010wt.% B to the starting steel.;COPYRIGHT: (C)1996,JPO