| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet excellent in surface characteristic and fishscale resistance, and its manufacture. SOLUTION: The steel sheet contains, by weight, >0.010-0.200% C, <=1.0% Si, <=3.0% Mn, <=0.15% P, <=0.05% S, 0.005-1.0% Cu, >=0.0001% O, <=0.02% N, >=0.015% Ti, and >=0.0005% Ca and/or metallic REM and also contains 0.005-0.2 wt.% non-oxide Ti (Ti*) and At in an amount satisfying (1) wt.%Ti/wt.%Al>=5 or (2) Al<=0.010% and wt.%Ti/wt.%Al<5. 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 deg.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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