摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet excellent in surface characteristic and baking hardenability, and its manufacture. SOLUTION: The steel sheet contains, by weight, 0.0003-0.010% C, <=1.0% Si, <=3.0% Mn, <=0.15% P, <=0.05% S, <=0.01% N, 0.010-0.50% Ti, and >=0.0005% Ca and/or metallic REM and also contains Al in an amount satisfying (1) wt.% Ti/wt.%Al>=5 or (2) Al<=0.010% and wt.%Ti/wt.%Al<5 and further contains 0.005-0.05 wt.% of non-oxide Ti (Ti*). At the time of its manufacture, a slab is heated and soaked at 900 to 1,300 deg.C, finish rolling is finished at 650 to 960 deg.C, coiling is done at 400 to 750'C, cold rolling is carried out at 50 to 95% draft, and the resultant sheet is subjected to recrystallization annealing at 700 to 920 deg.C.
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