STEEL MATERIAL FOR MULTIPASS WELDING EMPLOYING HIGH INTERPASS TEMPERATURE, ITS PRODUCTION PROCESS AND MULTIPASS WELDING PROCESS EMPLOYING HIGH INTERPASS TEMPERATURE

摘要

PROBLEM TO BE SOLVED: To provide a welding material for high interpass temperature welding which has a sufficient HAZ toughness, even when the interpass temperature reaches≥350°C, its production process and a welding process using this. SOLUTION: The steel material for multipass welding employing the high interpass temperature has a steel composition comprising, by mass, 0.07-0.15% C, 0.05-0.6% Si, 0.6-1.6% Mn,≤0.020% P,≤0.020% S, 0.005-0.025% Ti, 0.0030-0.070% N and the balance being Fe and unavoidable impurities, provided that Ti and N satisfy the relation: 2.0≤Ti/N. Here, TiN particles having an average particle size of≤100 nm are deposited in the steel at a distribution density of≥1×106/ mm2. COPYRIGHT: (C)2004,JPO