| 摘要 |
PROBLEM TO BE SOLVED: To obtain a welded joint having high fatigue strength by a simple welding method utilizing a low temp. transformation expansion by forming the welded metal of weld beads so that the starting temp. of the transformation from austenite to martensite at the toe part of welding is located in a specified range. SOLUTION: The welded metal is formed so that the starting temp. of the transformation from austenite to martensite in the weld bead is located in a range of 150-350 deg.C. The welded metal whose yield strength becomes 40-120 kg/mm2 at the starting temp. of the transformation is formed. On a structural member receiving the fatigue load, an out-of-plane gusset, cover plate or stud is welded. At both end parts of the out-of-plane gusset, a bevel part is arranged over the range of >=5 mm from the end parts, and the area of undeposit portion is reduced by >=10% compared to the area in the case of arranging no bevel part. The content of C, Ni, Cr and Mo in the welded metal is, by wt.%, C+Ni/12+Cr/24+Mo/19=0.85-1.3.
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