NON-HEAT-TREATED HIGH-STRENGTH STEEL MATERIAL SUPERIOR IN TOUGHNESS AT HEAT-AFFECTED ZONE IN SUPER HIGH-HEAT-INPUT WELD, AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To stably obtain superior toughness in not only a base metal but also a welded heat-affected zone of a high-strength steel with a tensile strength of 570 MPa or higher, even when the steel is subjected to super high-heat-input welding such as a welding heat-input of more than 1000 kJ/cm.;SOLUTION: The high-strength steel has the composition adjusted to comprise, by mass%, 0.001-0.03% C, 0.05-1.0% Si, 1.0-3.0% Mn, 0.1-0.6% Al, 0.010% or less Nb, 0.1-1.0% Mo, 0.0005-0.0030% B, 0.050% or less P, 0.0050% or less S and the balance Fe with unavoidable impurities.;COPYRIGHT: (C)2005,JPO&NCIPI