| 摘要 |
PROBLEM TO BE SOLVED: To provide a welded joint which has heat affected zone with excellent toughness and fatigue resistance. SOLUTION: The welded joint consists of high tensile strength steel having a composition containing, by mass, 0.01 to 0.1% C, 0.1 to 1.6% S, 0.5 to 2% Mn, <=0.01% P, <=0.005% S, 0.05 to 0.3% Nb, 0.001 to 0.05% Al, 0.001 to 0.05% Ti, 0.0002 to 0.006% Mg, 0.0001 to 0.008% O and 0.002 to 0.008% N, and the balance Fe with inevitable impurities, and satisfying Ceq <=0.45% and Pcm <=0.2%. One or more kinds of the single or combined particles of carbides, nitrides and oxides having a particle size of 0.002 to 5μm are dispersed into the steel, and the previousγparticle size in the structure of the heat affected zone is 10 to 200μm without depending on weld heat input. The final pass of the weld zone is formed by the weld metal whose Ms temperature reaches <=350 to >=150 deg.C.
|
