Influence of sulfur on the reaction between MnO-SiO₂-FeO oxide and fe-mn-si solid alloy by heat treatment

The diffusion behavior of Mn, O, and S at the interface between the oxide and solid steel must be clarified to understand the reaction between solid steel and inclusions containing sulfur at heat-treatment temperatures. In a previous paper, we investigated the reaction between the MnO-SiO₂-FeO oxide and an Fe-Mn-Si solid alloy by heat treatment using diffusion couple. In the diffusion couple experiments, fine particles were formed near the interface between the alloy and the bulk oxide after heat treatment owing to diffusion of oxygen from the bulk oxide to the alloy. In this study, by using the same diffusion couple method, we investigated the effect of sulfur on diffusion behavior. The width of the particle-precipitated zone (PPZ) and Mn-depleted zone (MDZ) decreased with increasing sulfur content of the bulk oxide and with decreasing sulfur content of the alloy. This result indicates that the diffusion of oxygen was suppressed by the diffusion of sulfur. The influence of sulfur on the formation of the MDZ and PPZ is discussed in terms of the difference in the driving force of sulfur diffusion and the direction of oxygen and sulfur diffusion.