WELDING METHOD FOR PROVIDING SUPERIOR TOUGHNESS TO HAZ OF MULTILAYER BUILD-UP WELDED JOINT OF HIGH TENSION STEEL

摘要

PURPOSE:To remarkably improve the toughness of a weld heat-affected zone (HAZ) at a lower temp. even in case of a high tension steel by restricting the compsn. of the high tension steel and cooling the HAZ in a prescribed temp. range in a specified time. CONSTITUTION:The compsn. of a high tension steel is composed of, by weight, 0.03-0.20% C, 0.05-0.50% Si, 0.50-3.0% Mn, 0.50-10.0% Ni, =0.010% P, =0.010% S, 0.01-0.10% Al, =0.0060% N, 0.0003-0.0030% B, 0.01-1.50% each of one or more among Cu, Cr and Mo and the balance Fe with inevitable impurities. The steel is subjected to multilayer build-up welding and the HAZ of the steel is cooled so that it is cooled from 800 deg.C to 500 deg.C in a time tau (sec) satisfying the formula. Thus, toughness at about -40--60 deg.C or below can be ensured for the HAZ in spite of the high tension steel.