STEEL PLATE SUPERIOR IN TOUGHNESS OF WELD HEAT-AFFECTED ZONE

摘要

PROBLEM TO BE SOLVED: To provide a steel plate for a welded structure, which is superior in the toughness of a weld heat-affected zone when having been subjected to welding with a high heat input exceeding 500 kJ/cm, and has a tensile strength of a 590 MPa grade or more.;SOLUTION: The steel plate has a steel composition including, by mass%, 0.025-0.050% C, 0.6% or less Si, 0.9-2.3% Mn, 1.0-3.9% Cr, 0.05% or less Al, 0.005-0.050% Ti, 2.0% or less (including 0%) Ni, while satisfying expression (1): 3.0≤Mn+0.7Ni+0.4Cr+2Si≤4.3; expression (2): Mn+0.7Ni≥1.6; and expression (3): Cr+5Si≥2.5, wherein Mn, Cr, Ni and Si represent contents (mass%) of each element, and the balance iron with unavoidable impurities.;COPYRIGHT: (C)2011,JPO&INPIT