| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a composite slab in a stable manner in which feeding control of a molten steel is facilitated, which has less variation in the concentration of a solute element in the width direction of a surface layer portion of a slab, and free from occurrence of powdery defects. SOLUTION: The DC magnetic field zone is impressed over the whole width of a slab across the thickness of the slab using independent magnetic poles vertically in double at an upper portion of a mold including the molten steel level in a continuous casting mold and at a center portion of the mold in the height direction of the mold spaced lower from the upper portion by a fixed distance, the molten steel is poured using a single immersed nozzle into a pool within or above the DC magnetic field zone impressed to the center portion of the mold, while adding a specified solute element to the molten steel within or above the DC magnetic field zone, so that the solute element of the molten steel in the upper pool is concentrated for regulating the concentration of the solute element in the surface layer of the slab. The impression of the magnetic field to the upper portion of the mold is carried out by superimposing the moving AC magnetic field to the molten steel level in addition to the DC magnetic field above described.
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