Formation, Evolution and Removal of MgO•Al2O3 Spinel Inclusions in Steel

MgO center dot Al2O3 spinel inclusions are generally found in steel, and required be controlled during steelmaking process due to the influences on continuous casting and the quality of final products. The present review aims to give an overall picture on the formation, evolution and removal of spinel inclusions. In this review, the reported formation mechanisms are reclassified, and the effects of Ca, Ti and Mn as well as rare earth on the evolution of spinel inclusions are summarized. Different methods with thermodynamic data sheets are also introduced for the calculation of phase stability diagram. To explain the evolution route of inclusions in industry, the sources and the formation kinetics of dissolved Mg and Ca are discussed. In addition, the agglomeration, separation and dissolution behaviors of spinel inclusions are considered, and the advantages of spinel inclusions are also addressed. Based on literature survey, some suggestions on the control of inclusions are given as well.