| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for selectively manufacturing various steel billets from cast slabs of a constant size with high operation efficiency and at a low equipment cost and a low operation cost in a continuous casting method by which a homogeneous cast slab comprising chill and columnar crystal is obtained by solidifying a hollow cast slab. SOLUTION: A hollow cast slab having a vacuum hollow is formed by causing a molten core to fall off in a stage of pulling up the cast slab to the 3/4 circumferential point in a bending type continuous casting method. A crude steel billet in which a hollow is enclosed is formed by extending the cast slab, omitting a solidification step, and cutting the cast slab by a bite-cutting system. When forming a crude steel billet into a steel billet of a desired size, restriction of rolling conditions is eliminated by allowing the hollow to remain, and the crude steel billet is rolled appropriately alternately vertically and horizontally by a reverse type rolling mill having flat rolls and a rapid reduction mechanism. A pass schedule is rapidly changeable at any time, so that a steel billet of optional size less than that of the cast slab is easily selectively manufactured. COPYRIGHT: (C)2011,JPO&INPIT
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