简介 |
PROBLEM TO BE SOLVED : To provide high strength steel for welded structure excellent in both of base metal toughness and weld part HAZ (heat affected zone) toughness.
SOLUTION : The high strength steel for welded structures excellent in both of base metal toughness and weld HAZ toughness has a composition comprising, by mass, 0.01 to 0.20% C, 0.02 to 0.50% Si, 0.3 to 2.0% Mn, ≤0.03% P, 0.0001 to 0.030% S, 0.0005 to 0.05% Al, 0.003 to 0.050% Ti, 0.001 to 0.010% N, and 0.0001 to 0.050% rare earth metals, and the balance iron with inevitable impurities, and in which the size of γ grains after heating is ≤50 μm. |