Evolution of Sulfides in Nonoriented Silicon Steels during Heating Process

Abstract

The evolution of sulfides in nonoriented silicon steels during the heating process is investigated through chemical composition analysis and thermodynamic calculation. Evolution behaviors of sulfides are analyzed using field emission scanning electron microscope (FESEM) and automatic scanning electron microscope (ASPEX). A homogeneous complex sulfide is detected containing magnesium and manganese. The different proportions of MgS and MnS in the complex sulfide are due to the competition between Mg, Mn, and S in low‐sulfur steel. Sulfides and compounds containing sulfides, oxides, and nitrides are mainly formed during the heating temperature of 1000 °C. The presence of sulfides and compounds with sulfide and oxide is at the temperature of 1300 °C. Sulfides reach equilibrium in less time than AlN at 1000 °C, while the time for sulfides to reach the theoretical equilibrium value takes precedence over oxides at 1300 °C. In addition, the proportions of various types of precipitation at 1300 and 1000 °C are discussed through the theoretical calculation and the observation results.