| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a thin steel sheet excellent in the uniformity of quality in the longitudinal direction of the steel sheet. SOLUTION: When the steel having composition composed of by mass 0.03-0.08% C, 0.03-0.5% Si, 1.0-1.8% Mn,≤0.01% P,≤0.03% S, 0.01-0.3% Mo and if necessary, one or more elements selected from among≤0.5% Cu,≤0.5% Ni,≤0.5% Cr,≤0.1% Nb and≤0.1% V and the balance essentially Fe, is acceleratively cooled to≤550°C at≥30°/sec cooling speed after hot-rolling at≥Ar<SB>3</SB>point temperature, an accelerative transport is performed at a fixed acceleration velocity since the leading edge of the steel sheet comes in the cooling apparatus until the tail end of the steel sheet comes out from the cooling apparatus and desirably, after a prescribed length of the leading edge of the steel sheet passes at fixed transport speed, the steel sheet is acceleratively transported at the fixed acceleration velocity to make the structure of the steel sheet into the structure mainly containing upper bainite over the whole length. COPYRIGHT: (C)2005,JPO&NCIPI
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