| 摘要 |
PROBLEM TO BE SOLVED: To provide steel having excellent low temperature toughness in a high heat input weld HAZ. SOLUTION: The steel for a welded structure has a componential composition satisfying the following expression (1) and in which the transformation point in a CCT curve at a cooling rate of≤2°C/s reaches≥670°C, or a componential composition satisfying the following expression (2). Further, the steel for a welded structure preferably comprises, by mass, 0.04 to 0.12% C, 0.01 to 0.5% Si, 0.5 to 2% Mn, 0.001 to 0.01% S, 0.04 to 0.08% sol.Al, 0.005 to 0.03% Ti, 0.001 to 0.003% B, 0.001 to 0.005% O and 0.004 to 0.007% N, and, if required, comprises one or more kinds of metals selected from≤0.5% Cu,≤1.0% Ni,≤0.5% Cr,≤0.5% Mo,≤0.1% V and≤0.03% Nb, and the balance Fe with inevitable impurities: 0.9×IN≤N≤1.2×IN (1), and T=A+B×[1+expä-C(LN(1/v)-D)}]<SP>-1</SP>≥670 (2). COPYRIGHT: (C)2005,JPO&NCIPI
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