| 摘要 |
PROBLEM TO BE SOLVED: To provide a continuous casting method capable of preventing or reducing occurrence of internal cracks when resulfurized free-cutting steel or the like is continuously cast, and obtaining a slab of free-cutting steel for machine structure having high quality. SOLUTION: In the continuous casting method or steel, when steel having a composition containing, by mass, 0.03 to 0.50% S, and in which Mn/S as a ratio between the mass content of Mn and the mass content of S is <20 is continuously cast, the casting is performed using a mold with a rectangular cross-sectional shape in which the ratio in the length of the long side to the short side is <1.5 and using a continuous casting machine in a vertical type, a curving type where straightening is performed after perfect solidification or a vertical bending type where bending and straightening are performed after perfect solidification. The diagonal ratio in the transverse section of the cast slab is controlled to≥0.99, and the bulging amount and depression amount of the slab are controlled to <4 mm, respectively. In the above method, the casting is preferably performed in such a manner that the casting velocity in a stationary state is controlled to <0.6 m/min. COPYRIGHT: (C)2009,JPO&INPIT
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