CONTINUOUS CASTING METHOD AND CONTINUOUSLY CAST SLAB

摘要

PROBLEM TO BE SOLVED: To provide a method for continuously casting a slab for producing a steel sheet having high performance of HIC (hydrogen-induced cracking) resistance, reducing center-porosity and macro- and semi-macro-segregation and to provide a continuously cast slab. SOLUTION: (1) The method for continuously casting the cast slab for producing the steel sheet excellent in the hydrogen-induced cracking resistance, is performed as the followings. In the cast slab position having≤60mm solidified shell thickness at one side, after bulging in the range of 3-10mm cast slab thickness, while keeping this state, the cast slab at the interval from the cast slab position where the solid phase is generated in the center part of the thickness, to the cast slab position where the center solid phase ratio is <0.8, is rolling-reduced as taper-state to the casting direction in the range of the bulged thickness and successively, the rolling-reduction is performed, as the stage-differential state by using one stage rolling-reduction roll pair at the cast slab position in the range of 0.8-0.95 center solid-phase ratio and in the range of 5-10mm in the cast slab thickness direction. (2) In the cast slab cast with the continuous casting method shown in the above (1), the continuously cast slab for producing the steel sheet, has≤2×10-4(cm3/g) porosity volume in the thickness center part of the cast slab. COPYRIGHT: (C)2007,JPO&INPIT