Reoxidation Behavior in Al Killed Steel during Casting

The kinetics of reoxidation of Al killed steel with slag and air were investigated in laboratory experiments using tammann furnace and in plant experiments using commercial 85×103 kg tundish. Experimental results were discussed by the coupled reaction model.Observed apparent rate constants of [sol.Al] decreased with increasing (CaO)/(SiO2) ratio in laboratory experiments and showed a good agreement with calculated ones.Flow rate of air leak at steady state was evaluated to be 3.0×10-5 and 4.0×10-4 m3/s inside and outside of immersion tube in commercial tundish, respectively and was estimated to have little influence on reoxidation.Mass transfer coefficient in metal was estimated to be 6.0×10-5 m/s based on the tundish mixing model and the coupled reaction model.Observed [sol.Al] in tundish decreased with increasing (%FeO)+(%MnO) value in ladle slag and showed a good agreement with calculated one by considering reoxidation in ladle and air leak at unsteady state.