STEEL HAVING EXCELLENT CTOD PROPERTY IN WELD HEAT AFFECTED ZONE AND METHOD FOR PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a high strength steel having excellent CTOD (Crack Tip Opening Displacement) properties which have not been obtained heretofore also satisfying the CTOD properties in an IC part in addition to the CTOD properties in an FL part at -60°C in multilayer welding ranging from low heat input welding to medium heat input welding, and to provide a method for producing the same.;SOLUTION: The steel having excellent CTOD properties in a weld heat affected zone has a composition comprising, by mass, 0.010 to 0.029% C, 0.05 to 0.20% Si, 0.7 to 2.5% Mn, ≤0.01% P, ≤0.005% S, ≤0.04% Cu, 0.003% Nb, 0.01 to 0.06% Al, 0.005 to 0.020% Ti, 0.002 to 0.006% N and ≤0.0035% O, and the balance iron with inevitable impurities. In the method for producing the steel having excellent CTOD properties in the weld heat-affected zone, the above molten steel is made into a slab by a continuous casting method, the slab is thereafter reheated to 950 to 1,100°C, and thereafter, TMCP (Thermo-Mechanical Control Process) is applied.;COPYRIGHT: (C)2011,JPO&INPIT