Investigation on Clogging of Submerged Entry Nozzles for GCr15 Bearing Steels

Clogging of submerged entry nozzles for GCr15 bearing steels has been investigated by industrial experiments coupled with mathematical simulations. It was found that clogs on the submerged entry nozzle with four ports were mainly CaO-MgO-Al2O3 inclusions with the size of 2–6 μm, which cannot be avoided by removal of inclusions from the liquid steel. Cathodoluminescence microscopy was also applied for the characterisation of submerged entry nozzle clogging. Mathematical simulations were carried out to predict the main clogging location at the submerged entry nozzle with different types. The results showed that the percentage of inclusions entrapped on the cylindrical submerged entry nozzle and four-port one was 39.7 and 46.5%, respectively. It indicated that the cylindrical submerged entry nozzle helped reduce the probability of submerged entry nozzle clogging and was beneficial for the improvement of the fatigue property of bearing steels.