| 摘要 |
PURPOSE:To form a sound cast slab with effectively avoidance from the development of internal crack and segregation by squeezing the cast slab at the suitable position just before completing solidification of internal part of the cast slab by suitable total-reduction quantity related to non-solidified thickness. CONSTITUTION:The cast slab 1 drawn from a mold 7 for continuous casting, through guide rolls 2 and pinch rolls 6, is stirred to the non-solidified part 1b by an electromagnetic apparatus 3 and also is squeezed the solidified shell 1a by squeezing die 4 providing reducing cylinder 5. Then, at the position showing 0.5-0.9 of solidus ratio fs of center part in the cast slab 1 or at the position, which thickness (d) of the non-solidified part 1b at center part is 1.2X(D-80)<1/2=(d)<=10.0X(D-80)<1/2>, the reduction satisfying delta/d<=0.5 is executed (where delta: total reduction quantity at squeezing mm, (d): non-solidified thickness at the squeezing position mm, D: cast slab thickness before squeezing mm). In this way, the development of internal crack and negative segregation caused by pressing work is effectively avoided, and center segregation, especially semi- macro segregation, too, is easily improved.
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