PRODUCTION OF STEEL EXCELLENT IN TOUGHNESS OF WELDING HEAT-AFFECTED ZONE

摘要

PROBLEM TO BE SOLVED: To provide a method for producing steel small in the variation of the material in the thickness direction and also excellent in the toughness of the welding heat-affected zone.;SOLUTION: As to this method for producing steel, a steel stock, which contains, by weight, 0.01 to 0.03% C, 0.05 to 0.10% Nb, 0.0003 to 0.0050% B and 0.005 to 0.050% Ti, in which the ratio of the Ti content and Al content, i.e., Ti/Al satisfies ≥5.0, moreover contains one or two kinds of Ca and rear earth metals, and in which oxide inclusions having an inclusion compsn. composed of, by weight, 20 to 90% Ti oxide, ≤70% Al2O3, one or two kinds of Ca oxide and REM oxide by 5 to 50% in total and ≤15% MnO are dispersed, is heated to the temp. range of 950 to 1,250°C and is thereafter subjected to hot rolling in which the cumulative draft in the temp. region of ≤950°C is controlled to ≥20%, and the rolling finishing temp. is controlled to ≥800°C.;COPYRIGHT: (C)2000,JPO