| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet having excellent toughness in a weld heat-affected zone even in the case high heat input welding exceeding >500 kJ/cm is performed and having tensile strength of≥490 MPa by a componential composition to which expensive elements such as Ni and Mo are not added. SOLUTION: A steel having a composition comprises, by mass, 0.01 to 0.03% C,≤0.5% Si, 2.3 to 3.5% Mn, 1.0 to 2.5% Cr,≤0.05% Al and 0.005 to 0.050% Ti, and satisfying 35Cr+8Mn≥63 and 6Cr+4Mn≤24, and the balance iron with inevitable impurities; wherein, Cr and Mn are addition (%) in each inequality. COPYRIGHT: (C)2010,JPO&INPIT
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