Are superior in tenacity of 1 formation full house thermal welding thermal effect section the high intensity thick steel sheet and its production

摘要

PROBLEM TO BE SOLVED: To provide a high strength thick steel plate having ≥12 mm thickness which is suitable for a building structure, has base material performance of ≥780 MPa tensile strength and is capable of attaining stable high toughness in an one layer large heat input welding HAZ having above 400 kJ/cm welding heat input.;SOLUTION: The steel plate contains, by mass, 0.03-0.09% C, 0.05-0.40% Si, 1.0-3.0% Mn, 0.3-3.0% Cr, ≤0.02% P, ≤0.0050% S, 0.01-0.05% Al, 0.005-0.03% Ti, 0.0025-0.0070% N, 0.0005-0.005% Ca and if need, one kind or two or more kinds of Cu, Ni, Mo, Nb, V, B, REM and Mg, 30-42 (%) value in the following formula and the balance FE and inevitable impurities: 27C+9Mn+4(Cu+Ni)+8(Cr+Mo), wherein each content (mass%) of C, Mn, Cu, Ni, Cr, Mo is expressed and elements which are not contained are made 0.;COPYRIGHT: (C)2011,JPO&INPIT