| 摘要 |
PURPOSE: A method for producing a continuously casting shell of Bi-S free cutting steel is provided to minimize inclusions in steel, to reduce pin holes and blow holes in a shell, to improve the degree of central segmentation and to reduce surface breakage in a billet. CONSTITUTION: Bi-S free cutting steel contains 0.036wt% of carbon, less than 0.5wt% of silicon, 1.20-1.40wt% of manganese, 0.07-0.09wt% of phosphorous, 0.270-0.330wt% of sulphur, 0.08-0.16wt% of bismuth, less than 70ppm of nitrogen and 80-150ppm of boron. F(O) is controlled to be 25-100ppm in a tundish. Casting speed is controlled at 0.60-0.70m/min.
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