PRODUCTION OF MILD STEEL INGOT FOR BAR AND WIRE BY CONTINUOUS CASTING

摘要

PURPOSE:To produce a titled ingot superior in quality and characteristics by subjecting the molten steel produced to have specific tapping C% in a converter to vacuum deoxidation then to Al auxiliary deoxidation and continuously casting the same at specific speeds while preventing the formation of air bubbles. CONSTITUTION:The molten steel produced to have product target C%+0.02- 0.05% tapping C% in a converter is subjected to vacuum degassing treatment. By this treatment, the deoxidation by C+O reaction is progressed at far as possible in the molten steel under reduced pressure. Thence, further the remained free O is deoxidized by a small amount of Al, to control the entire O at 40-90ppm. Next, this molten steel is continuously cast at =0.8m/min casting speeds so that the formation of air bubbles by the C+O reaction during casting is prevented. In this case, the mild steel ingot (C=0.25%) for bars and wires of superior drawability, suitability for cold forging, machineability, etc. is produced by the converter-vacuum degassing treatment-continuous casting.