Casting simulation of calcium titanate and calcium zirconate nozzles for continuous casting of aluminum-killed steels

The clogging of submerged entry nozzles (SENS) and tundish well nozzles is a common problem in the continuous casting of aluminum-killed steels. Clogging occurs when alumina attaches to the inside of the nozzle restricting the flow. This article explores the use of new nozzle materials that could prevent accretion growth through the formation of liquid phases at the inclusion-refractory interface. Casting simulation experiments were conducted using three nozzle refractory formulations: calcium titanate, calcium zirconate, and a 2:1 calcium titanate to calcium zirconate molar mixture. Nozzles fabricated from these materials cast more aluminum-killed steel without clogging than typical industrial alumina graphite nozzles. However, the nozzles constructed of calcium titanate dramatically outperformed alumina graphite, calcium zirconate, and the mixed nozzles. Microscopy investigation of spent nozzles found no accretion formation in the calcium titanate nozzles. The performance difference was due to the formation of a liquid calcium aluminum titanate phase, which prevented alumina accretions.