Evolution and Transformation of Inclusions in Calcium-Treated Low-Carbon Si–Mn-Killed Steel

In this study, industrial trials were conducted on Si–Mn-killed steels to study the evolution of inclusions and their transformation in steel to meet stringent steel quality. It is observed that inclusions modify along the route of ‘‘MnO–SiO₂-based inclusions to CaO–Al₂O₃-based inclusions after calcium treatment and further transformed to CaO–SiO₂–Al₂O₃-based inclusions’’ in billet stage. As more dissolved oxygen is present in Si-killed steel compared to Al-killed steel; a new generation of SiO₂ is taking place during solidification that too adjacent to liquid oxide inclusions (in tundish samples) which are getting transformed to wollastonite and anorthite at the billet stage. The results obtained from industrial trails denoting calcium treatment in Si–Mn-killed steels has an efficient method to get better castability of liquid steel and also is affable to enhance deformation ability of inclusions in steel further during cold rolling process.