| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel member for high-heat input welding in which the formation of insular martensite in the weld heat-affected zone is suppressed without performing the addition of expensive alloy elements, and which has high strength, and in which the toughness of the weld zone is excellent. SOLUTION: The steel member for high-heat input welding has a composition comprising, by mass, 0.01 to 0.03% C, 0.01 to 0.15% Si, 2.6 to 3.5% Mn,≤0.008% P, 0.0005 to 0.0040% S, >0.005 to <0.1% Al, 0.003 to 0.03% Ti, 0.0025 to 0.0070% N and 0.0003 to 0.0025% B, and in which the area fraction of insular martensite in the structure of the heat-affected zone in the vicinity of a bond when being subjected to high-heat input welding having a welding input heat of >300 kJ/cm is≤1%. COPYRIGHT: (C)2011,JPO&INPIT
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