Submerged arc weld metal excellent in cryogenic toughness and submerged arc welding wire and flux forming it

摘要

PROBLEM TO BE SOLVED: To add ultralow-temperature toughness to a weld metal of an UO steel pipe for a line pipe which is used in an ultralow-temperature range of -60°C.SOLUTION: The weld metal includes, by mass, 0.03 to 0.10% C, 0.05 to 0.50% Si, 0.80 to 2.20% Mn, 0.015% P, 0.010% S, 0.500% or less Cu, 0.050% or less Nb, 0.020% or less V, 0.020 to 0.035% O, 0.0045% or less N, 0.003 to 0.018% Al, 0.005 to 0.025% Ti, 0.0004 to 0.0040% B, 0.0001 to 0.0020% solid-solved B, and the balance Fe with inevitable impurities, where Pis 0.12 to 0.30 and an O amount and a B amount, the O amount and an Al amount, and the O amount, an N amount, the Al amount, a Ti amount respectively satisfy specific relational expressions.