IMPROVEMENT OF CASTABILITY THROUGH CONTROLLED SLAG COMPOSITION IN SECONDARY METALLURGY

Objective. Ultraclean steel grades are opening up new possibilities fo r processing and use in terms of material and application technique. A precondition for producing extremely clean steel grades is the optimi sation of the secondary metallurgical measures and processes. Presente d is the practice of slag composition control in secondary metallurgy at Huttenwerke Krupp Mannesmann GmbH. Summary. The cleanness and homog eneity of steel products have been continually improved over the past few years and nowadays, for example, enable complicated autobody compo nents to be formed in one piece. The metallurgical measures for produc ing ultraclean steels are known and controllable. The macroscopic clea nness of the steels is decisively influenced by turbulences during cas ting. Interactions between the steel bath and ladle slag, and alumina- forming reactions after completion of the homogenising treatment, can lead to the formation of macroinclusions. Such undesirable reactions c an be suppressed by intensively treating the steel and slag together, or by means of a controlled slag composition. The results of an optimi sed slag composition are presented. The homogeneity thereby achievable for the casting process brings about an improvement in cleanness.