Influence of reoxidation by slag and air on inclusions in IF steel

¹ School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
e-mail: qym_0604@126.com
² Shougang Technology Research Center, ShouGang Corporation, Beijing 100087, P.R. China

Received: 2 February 2015
Accepted: 6 July 2015

Abstract

By investigating the variation in T.O, [Als], and the morphology and composition of inclusions during the IF steel production process, a comparison between two processes with different ladle slag oxidation states (Process A < Process B) was made to understand the effects of slag reoxidation (steel reoxidation by slag) during RH treatment, slag reoxidation during the waiting time and air reoxidation (steel reoxidation by air) at the initial stage of casting on the inclusion behavior. The results showed that the [Als] loss rates of the three reoxidation types were in the following order: slag reoxidation during the waiting time < slag reoxidation during RH treatment < air reoxidation at the initial stage of casting, and the strong ladle slag oxidability and the good stirring effect on molten steel would accelerate the reoxidation rate. In addition, the generation of inclusions in the bulk of molten steel was not observed during RH treatment but during the waiting time, and these newly generated Al₂O₃-Ti_xO inclusions with Ti/(Ti + Al / 2)% > 60 due to air reoxidation in the tundish were different in size distribution from those due to slag reoxidation during the waiting time.