Inclusion engineering: a keytool in achieving steelmaking operations stability at OneSteel Whyalla

Abstract

A new billet casting machine and ladle metallurgy furnace were commissioned at OneSteel (formerly BHP) Whyalla steelworks in June and October of 1999. The production of low Mn/Si ratio grades using, at first, an oxygen reheating station, and then later a ladle metallurgy furnace, provided many challenges to the achievement of stable steelmaking and casting operations. The multiphase equilibrium model as developed by the Commonwealth Scientific Industrial Research Organisation (CSIRO) has been used to solve complex metallurgical problems of practical importance in the production of silicon killed steels. Subtle changes to ladle practice for dissolved oxygen content combined with calcium treatment dictates inclusion composition and liquidus. Inclusion composition control has been a key requirement for making open cast product with good surface quality, and also for the control of refractory stopper erosion for submerged cast grades.