The thick steel sheet null mass which possesses the yield strength above 460MPa which is superior in CTOD property of the welding

摘要

PROBLEM TO BE SOLVED: To provide a thick steel plate which has yield strength of 460 MPa, and in which CTOD at -10C in HAZ is 0.2 mm.;SOLUTION: The thick steel plate having yield strength of 460 MPa and excellent CTOD characteristics in the heat affected zone has chemical components containing, by mass, 0.04 to 0.14% C, 0.4% Si, 1.0 to 2.0% Mn, 0.02% P, 0.001 to 0.005% S, 0.001 to 0.01% Al, 0.005 to 0.03% Ti, 0.005 to 0.05% Nb, 0.0003 to 0.005% Mg, 0.001 to 0.005% O and 0.001 to 0.01 N, and the balance iron with inevitable impurities. TiN of 0.01 to 0.5 m involving oxides consisting of Mg and Al is present by 10,000 pieces/mm2. Also, the particles of 0.5 to 10 m containing 0.3 wt.% Mn are present by 10 pieces/mm2 in a form in which oxides and sulfides are combined.;COPYRIGHT: (C)2002,JPO