High purity steels: a challenge to improved steelmaking processes

Abstract

Rising demands on material properties of many steel grades lead to the need for a further reduction of undesirable impurities, especially non-metallic inclusions. Suitable metallurgical processes have to be used to meet this requirement. At the steel plant of Dillinger Hüttenwerke, the production of high quality steels with very low sulphur and oxygen contents is essentially achieved by in-ladle secondary metallurgy of liquid steel and by the use of vertical continuous casters. For improving the steel cleanness, various plant trials were carried out with special attention to steel desulphurisation, the removal of total oxygen by cleanness stirring, and tundish inertisation with argon as well as the selection of suitable tundish covering fluxes. Results obtained from the trials are presented.