PURPOSE: To prevent surface cracking and cracking under surface layers without need for preliminary working by controlling P and S to be contained in steel at contents smaller than prescribed values and cooling the secondary cooling zone from right under a mold at a prescribed cooling water ratio.
CONSTITUTION: Steel limited to ≤0.007wt% P and ≤0.003wt% S to be contained and contg. 7.5W10wt% Ni is melted. Thereafter, the molten metal is cast into a continuous casting mold and is cooled at 0.4W1l/kg secondary cooling water ratio expressed by the equation from right under the mold up to the position where the leveling of a slab starts. Thus, the need for preliminary working is eliminated and surface cracking and cracking under the surface layers are prevented.
TANIGAWA OSAMU
KOMAMURA KOUICHI
IMAI TAKUO
