Interfacial Reaction Between Ultra Low C Steel and Gas Generated from Refractory Material Used for Submerged Entry Nozzle for Continuous Casting

For a number of steelmakers, Ultra Low Carbon (ULC) steel is one of the major products of high quality steels. The slab of the ULC steel is produced by a continuous casting process in order to maximize the process efficiency. Ti is one of the important alloying elements of the ULC steel in order to secure a good formability of the steel as it is used for outer panels of automobiles. It has been a long problem that an increase of Ti content in the steel increases the extent of nozzle clogging during the continuous casting process. In the present study, the clogging phenomena for the Ti-ULC steel is reviewed, and a possible source of the formation of the clogging material is discussed. Particular attention has been paid to the interfacial reaction between the Ti-ULC steel and the refractory material used for a submerged entry nozzle. A phase diagram of the steel-refractory system is applied to figure out which types of materials are formed and how Ti affects the formation of such a material at the interface between the steel and the refractory.