Affiliation:
1. The State Key Laboratory of Rolling and Automation Northeastern University Shenyang Liaoning Province 110819 P. R. China
Abstract
The microstructure and composition of the scales formed are examined after being exposed to atmosphere containing 2.0% SO2 + 5.0% O2 for 60 min in the temperature range of 900–1200 °C. The composition of the scale post‐oxidation primarily varies with temperature rather than silicon content. FeS exhibits a melting temperature of 950 °C, whereas FeSi2O4 melts at 1150 °C. Two mechanisms for FeS formation are proposed. Eutectoid transformation of molten FeS occurs during subsequent cooling, resulting in lamellar FeS + Fe–S–O compounds. Above 1150 °C, the melt of Fe2SiO4 further increases the Fe diffusion rate. This dual‐liquefaction mechanism involving FeS and Fe2SiO4 accounts for the anomalous oxidative mass gain observed in Fe–Si alloys exposed to a sulfur‐containing atmosphere.