Low Superheat Teeming with Electromagnetic Stirring

Abstract

It is well known that center segregation of continuous casting steel is much improved by low superheat casting. However, the low superheat casting is not utilized because of the problem of nozzle clogging. The techniques of electromagetic stirring and reduction technique have been employed to improve the segregation even under the high superheat casting. In these methods, a large amount of equiaxed crystals is favorable to maintain the internal quality. Therefore, low superheat casting method by a new type nozzle with air cooling and electromagnetic stirring was devised and teeming experiment using 500 kg or 3 t molten steel was carried out to investigate the cooling ability of the nozzle.
With increasing the intensity of stirring, the flow rate was reduced by the effect of electromagnetic value and the temperature drop in the nozzle was increased from 22 to 50°C. From the experiment, thermal resistances of each part of nozzle were obtained, and it was estimated that temperature drop of 30°C is gained when the nozzle is applied to billet continuous casting.