| 摘要 |
PROBLEM TO BE SOLVED: To reduce the central segregation of a cast slab, and also, to improve the lives of segments composing a light rolling-reduction zone, when a continuously cast slab of steel is manufactured by gradually applying rolling reduction to the cast slab having an unsolidified inner portion with a rolling reduction speed corresponding to the amount of solidification contraction in the light rolling reduction zone arranged in the secondary cooling zone. SOLUTION: In a method for manufacturing a continuously cast slab, the thickness of an unsolidified layer 14 inside the slab is increased by intentionally exerting a bulging force on a solidified shell 13 in an intentional bulging zone 17 arranged between a lower end of a continuous casting die 5 and a crater end of the liquid phase line of a cast slab 12, and then, in a light rolling reduction zone 16, the rolling reduction is applied to the slab with the rolling reduction speed within the range of 0.5-1.5 mm/min from the position where the solid phase ratio at the central portion of the thickness of the cast slab is 0.4 or lower until the position where the solid phase ratio at least at the central portion of the thickness of the cast slab becomes 0.7 or over. The total amount of rolling reduction of the cast slab is made equal to or smaller than the bulging amount of the cast slab when the cast slab is intentionally bulged. COPYRIGHT: (C)2010,JPO&INPIT |
