| 摘要 |
<P>PROBLEM TO BE SOLVED: To manufacture continuously cast slabs having small central segregation, which meet recent severe quality requirements by improving efficiency of light rolling reduction in continuously casting the molten steel while applying the light rolling reduction to the cast slabs. <P>SOLUTION: There is provided a method for manufacturing a cast slab, which includes: intentionally applying bulging force to a solidification shell 13 between the lower end of a mold 5 for continuous casting and the liquidus line crater end of a cast slab 12 to increase the thickness of an unsolidified layer 14 in the cast slab; and carrying out rolling reduction in a light rolling reduction zone 16 at a reduction rate within a range of 0.5 to 1.5 mm/min at least until a point of time when the solid phase rate at the central portion of the thickness of the cast slab reaches 0.7 or larger from a point of time when the solid phase rate is 0.4 or smaller. The cast slab is subjected to the rolling reduction by increasing smoothness of a cast slab width-directional shape of the solid-phase line crater end by controlling the maximum descent flow rate of molten steel at 0.75-0.85 m below a molten steel level in the mold to 0.05-0.3 m/second under control over a molten steel flow in the mold, and controlling a cast slab surface temperature on a central portion side except for a corner part on a cast slab long side surface to 750-1,000°C. <P>COPYRIGHT: (C)2013,JPO&INPIT |
