MANUFACTURE OF STEEL MATERIAL SUPERIOR IN WELDED JOINT HEAT AFFECTED ZONE TOUGHNESS

摘要

PURPOSE:To obtain the titled material, by deoxidizing molten steel contg. specified quantities of disoolved O2, Al, Si by Ti, casting and rolling said steel to causing a specified compsn. and incorporating a specified quantity of oxide inclusions such as TiO2 having a specified particle diameter therein. CONSTITUTION:Ti is added into molten steel contg. =0.020% dissolved O2, =0.007% and =0.05% inevitably mixed Al, Si respectively to deoxidize it. Next, said steel is cast or cast rolled to prepare a steel material contg. by wt. 0.001-0.300% C, 0.4-2.0% Mn, =0.025% P, 0.025% S, =0.007% Al, 0.003-0.050% Ti, 0.0010-0.0100% ) and the balance Fe with impurity elements and =0.004-0.100% range of oxide inclusions having =3mu particle diameter and contg. crystal phase of either one or compounded 2 kinds of TiO, Ti2O3.