| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for stably producing a hot rolled steel sheet excellent in ductility without depending on the addition of a large amt. of B. SOLUTION: A slab having a componental compsn. contg., by weight, 0.015 to 0.050% C, 0.05 to 0.5% Mn, <=0.01% S, 0.005 to 0.100% Al, <=0.005% N, 0.0002 to 0.0015% B, Ti: (48/14)N%<=Ti<=(48/14)N%+0.010%, and the balance Fe with inevitable impurities is heated at 1150 to 2550-(2815×log(Ti wt.%) (N wt.%)/[(log(Ti wt.%) (N wt.%)-5.9)] deg.C, is subjected to finish rolling at the Ar3 point or above and is coiled at >=500 deg.C.
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