Behaviors and Evolutions of MgO·Al2O 3 in Non-Oriented Silicon Steel During Calcium Treatment

Behaviors and evolutions of MgO·Al₂Q₃ in non-oriented silicon steel during calcium treatment were investigated by thermodynamic calculations and high-temperature experiments. MgO·Al₂O₃ inclusions were the main type of inclusions before calcium treatment, which is also confirmed by the stability diagram of MgO/MgO Al₂O3/Al₂Q₃ from thermodynamic calculations. After calcium treatment, the majority of original MgO·Al₂Q₃ inclusions were mainly modified to CaO-MgO-Al₂Q₃ system inclusions, this would be beneficial to improve castability and product quality of silicon steel. But there was no modification happening to some MgO·Al₂Q₃ spinels which were directly surrounded by CaS inclusions. The content of Al₂O₃ occasionally existed a sudden increase besides a common decrease in the product layer of CaO·MgO Al₂O₃. Then the evolution mechanisms of MgO·Al₂O₃ inclusions were proposed in present work. Thus, Al/Mg atom ratio had a significant influence on the modification of MgO·Al₂O₃ spinel.