Effect of nozzle base material on the rate of clogging during the continuous casting of aluminum-killed steels

Abstract

One approach to solving the problem of nozzle clogging during the continuous casting of aluminum-killed steels is through careful selection of nozzle materials. In this study, the rate of clogging was measured while casting steel through simulated nozzles produced from alumina, zirconia, magnesia, zirconia-graphite, and alumina-graphite - three common base materials and two common carbon-containing nozzle materials. Spent nozzles were characterized using optical and cathodoluminescence microscopy. Interactions between the nozzles and steel were not observed in the alumina, zirconia, and zirconia-graphite nozzles. Slight interactions were observed in the magnesia nozzles as alumina inclusions within the steel interacted with the nozzle to produce alumina-magnesia spinel. Greater amounts of interaction were observed with alumina-graphite nozzles. No statistical differences in the mean rate of clogging were observed between all of the pure oxide nozzles and zirconia-graphite nozzles. However, the alumina-graphite nozzles clogged at a much higher rate than the other nozzles. The higher rate of clogging is thought to be due to refractory-steel interactions.