CONTINUOUSLY CAST STEEL SLAB FOR HIGH TOUGHNESS STEEL HAVING EXCELLENT SURFACE CRACK RESISTING SENSITIVITY

摘要

PROBLEM TO BE SOLVED: To provide a continuously cast steel slab for a high toughness steel which has excellent surface crack resisting sensitivity.;SOLUTION: The continuously cast steel slab for a high toughness steel having excellent surface crack resisting sensitivity has a composition comprising, by mass, 0.02 to 0.2% C, ≤0.6% Si, 0.3 to 2.5% Mn, ≤0.02% P, ≤0.01% S, 0.001 to 0.05% Al, 0.0075 to 0.02% Ti, 0.005 to 0.05% Nb, 0.005 to 0.01% N, and 0.001 to 0.005% O. The continuously cast steel slab further comprises one or more kinds selected from 0.0005 to 0.005% Mg, 0.002 to 0.02% La+Ce and 0.0005 to 0.005% Ca, also satisfies formula (1) calculated by using mass%: Ti/N=1.5 to 3, and inequality (2): N≤-0.102Al+(-0.09Nb+0.0106), and the balance iron with inevitable impurities.;COPYRIGHT: (C)2005,JPO&NCIPI