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

摘要

PROBLEM TO BE SOLVED: To provide a cast slab which suppresses the occurrence of crack on its surface in the continuous casting and reduces load of caring cast slab at adding alloy elements such as Ni for improving toughness at a low temperature.;SOLUTION: A continuous cast slab for high toughness steel having excellent surface crack resisting sensitivity is provided by making the composition of the cast slab consist of C:0.02 to 0.20%, Si:0.01 to 0.6%, Mn:0.3 to 2.5%, Ni:0.2 to 5.0%, P:0.030% or less, S:0.020% or less, Al:0.005 to 0.03%, O:0.001 to 0.005% and N:0.0001 to 0.006% and consist of one or more kinds of Ti:0.0075 to 0.2%, V:0.005 to 0.1%, Nb:0.005 to 0.05%, Mo:0.05 to 1.0% and have relationships as 4/47.9×Ti+3/50.9×V+2/52.0×Cr+3/92.9×Nb+2/95.9×Mo2/58.7/20×Ni.;COPYRIGHT: (C)2014,JPO&INPIT