| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel excellent in a low temperature toughness without increasing the adding quantity of micro-alloy. SOLUTION: A method for producing the high toughness steel includes the following process. A steel blank having composition composed of, by mass%, 0.01-0.20% C, 0.01-0.80% Si, 0.20-2.0% Mn,≤0.020% P,≤0.0070% S, 0.003-0.100% sol.Al and the balance Fe with inevitable impurities is heated to the temperature in the austenite temperature range and≤1200°C, and after rolling the blank in the austenite-crystallizing temperature range, and when the rolling is performed in the temperature range of non-recrystallizing upper limit temperature or lower to Ar<SB>3</SB>point or higher, the rolling is divided into two or more stages, and before the secondary and thereafter rolling is performed, the rapid-heating of 2°C/sec, is applied by an induction-heating apparatus near the rolling-mill to perform the temperature compensation, and the accumulated rolling-reduction at≥70% in the temperature range of the non-recrystallizing upper limit temperature or lower to the Ar<SB>3</SB>point or higher, is applied and the accelerated cooling from the Ar<SB>3</SB>temperature or higher to≤600°C, is performed. COPYRIGHT: (C)2010,JPO&INPIT
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