Effect of Si and Ce Contents on the Nozzle Clogging in a REM Alloyed Stainless Steel

Abstract

The influence of the cerium and silicon contents on the castability of a REM-alloyed stainless steel was investigated by using pilot scale experiments. The trials were carried out with three different silicon concentrations: i) low (LSi; Si < 0.5%); ii) middle (MSi; Si ≈0.8−1.4%); and iii) high (HSi; Si ≈1.5−1.9%). During the casting, the liquid steel was teemed out through a zirconia nozzle located at the bottom of the furnace. The results showed that the nozzle clogging did drastically increase with increasing concentrations of Si and Ce up to levels larger than the critical contents (≥1.5% Si and ≥0.05% Ce) in the cast HSi steel. In addition, the Ce content in a cast steel was found to increase linearly with an increased concentration of Si, due to the determinant effect of the Si content on an initial content of O in the melt before an addition of mischmetal. Finally, it was found that the concentration of insoluble Ce (Ceinsol.) determines the amount of inclusions and clusters in steel samples. Overall, soluble Ce concentrations larger than 250 ppm were found to be an important reason for fast nozzle clogging during casting.