The Relationship between MnS Precipitation and Induced Nucleation Effect of Mg-Bearing Inclusion

The relationship between MnS precipitation and induced nucleation effect of Mg-bearing inclusion has been explored through scanning electron microscope and energy dispersive spectrometer (EDS). Results indicate that MnS prefers to precipitate on Mg-bearing inclusions. Statistical analysis suggests that MgAl2O4 and MgO may coexist in inclusion. After etching, it is found that Mg-bearing inclusions can induce the nucleation of intragranular acicular ferrites. Based on EDS line analysis and comparison with Al-Mn-Si-O inclusion in non-Mg-treated sample, this effect can be explained by Mn-depletion zone (MDZ), which is due to the vacancy property and crystal structure of MgAl2O4. In the same sample, similar induced nucleation effect and MDZ are not observed around pure MnS. This comparison implies that the formation of MDZ may be independent of MnS precipitation.