Effects of Refractory and Ladle Glaze on Evolution of Non-Metallic Inclusions in Al-Killed Steel

Laboratory experiments are carried out to study the effects of different refractories (Al2O3 refractory, MgO refractory, and glazed Al2O3 refractory) on the formation of spinel inclusions and calcium aluminate inclusions. The results show that Al2O3 refractory has almost no influence on the inclusions in Al-killed steel, while MgO refractory and glazed Al2O3 refractory can help the formation of spinel inclusions from alumina inclusions. Meanwhile, glazed Al2O3 refractory can also contribute to the transformation of spinel inclusions into calcium aluminate inclusions. In contrast to ladle glaze, MgO refractory could supply more dissolved Mg to liquid steel. The formation of dissolved Mg and Ca holds the key for the evolution sequence of alumina, and spinel inclusions form earlier than calcium aluminate inclusions due to the faster formation of dissolved Mg. Besides, ladle glaze can also be a source of calcium aluminate inclusions.