| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a steel material excellent in the toughness at a welding heat-affected zone. SOLUTION: To a steel blank having composition composed by mass% of 0.01-0.15% C, 0.05-0.70% Si, 0.6-2.5% Mn,≤0.030% P,≤0.0060% S, 0.005-0.10% Al and 0.005-0.040% Ti, 0.0015-0.0100% N under condition of satisfying Ti/N: 0.8-4.0, and the balance Fe with inevitable impurities, after heating at a temperature in the range of 1000-1300°C for≥5 hr, the steel blank treatment for cooling to≤700°C is applied and thereafter, the hot-working is applied. Thereby, in the whole portion in the plate thickness direction, the toughness as the welding heat affected zone is improved over the wide range of welding heat input. COPYRIGHT: (C)2005,JPO&NCIPI
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