Improvement of castability and anality of continuously cast steel

Thermodynamic fundamentals on the systems Fe-Al-O and Fe-Al-Ca-S-O being im portant to metallurgy of Ca-treated Al-killed steels are analysed and discu ssed. The formation of liquid Ca aluminates for the improvement of castabil ity is pursued in view of the production of Ca-treated Al-killed steels. Th e "Liquid window" is theoretically analysed and experimentally investigated . The top slag is formed after tapping and its composition is fairly consta nt during ladle treatment for both with and without RH treatment, respectiv ely. However, the top slag of the degassed heats shows a lower oxygen level compared to the non-degassed heats. It is found that there exists an "incl usion path" during the ladle treatment. The inclusion path for the heats wi th RH treatment considerably differs from that of the heats without RH trea tment and it greatly influences the efficiency of Ca treatment.