COLD ROLLED STEEL SHEET GOOD IN DEEP DRAWABILITY, SMALL IN PLANE ANISOTROPY AND EXCELLENT IN RIDGING RESISTANCE AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To provide a steel sheet having high Lankford value and low plane anisotropy, good in ridging resistance and producible at a low cost by low Ti-low Nb extra-low C steel low in recrystallizing temp. and good in ductility. ;SOLUTION: A steel sheet contg. components of, by weight, 0.0040% C, 0.030% Ti, 0.005% Nb and 0.005% Ti* [where Ti*=Ti-48 (C/12+N/14+S/32)], in which the density of precipitates of ≥0.005 μm diameter is ≤10 pieces/μm3, and the density of precipitates of ≥0.10 μm diameter is ≥0.010 pieces/μm3 and having ≥0.4 mm sheet thickness is reheated in the temp. range of ≥900°C for ≥30 min in a heating furnace without executing cooling to ≤850°C after casting or without executing cooling to ≤500°C after casting, is hot-rolled and is subjected to a cold rolling stage at 60 to 90% cold rolling draft and an annealing stage to produce this cold rolled steel sheet.;COPYRIGHT: (C)2000,JPO