The effects of inclusions in steel on MnS precipitation in Fe-Si alloys

Abstract

"In-situ" observation of MnS precipitation in Ce-added and Zr-added Fe-Si alloys was made on cooling using a confocal scanning laser microscope. In Ce-added and Zr-added sample, the temperature at which MnS precipitation started became higher because of the heterogeneous nucleation of MnS on Ce2S3 and ZrO2. By SEM observation, it was found that many MnS precipitates were neighboured on Ce2S3 and ZrO2. But in case of the sample contained much Ce, the temperature at which MnS precipitation started became lower and the amount of MnS precipitates became less. It was because the sulfur was consumed in Ce2S3 and the solubility product of manganese and sulfur became small. The number of MnS precipitates in δ and γ phase was very different in the sample contained neither Ce nor Zr, but that number became almost equal by the addition of Ce and Zr.