To provide the welded structure excellent in low-temperature toughness by providing the base metal of the mixed structure of martensite and a lower bainite, providing the weld metal in which O of the prescribed quantity is contained, and P cm and Al/O are specified, and specifying TS of the base metal and the weld metal.
The welded structure is formed of the base metal and the weld metal. The metallic structure of the base metal substantially consists of the mixed structure of the martensite and the lower bainite. The base metal is the steel of ≥TS900 Mpa. The weld metal is the steel containing ≤0.06% O, satisfying the inequalities I and II, and whose TS is ≥900 Mpa. The element symbol in the formulae I and II means the content (wt.%) of each alloy element in the steel. The weld metal contains 0.01-0.15% C, 0.02-0.6% Si, 0.6-3% Mn, 0.004-0.08% Al, 0.003-0.03% Ti, ≤0.06% O, 0.0002-0.005% B, 0-1.2% Cu and Cr, 0-3% Ni, 0-1% Mo, 0-0.05% V and Nb.
KOMIZO YUICHI
KADONAGA TAKESHI
