Effect of interfacial properties on the clustering of alumina inclusions in molten iron

Clustering of alumina inclusions in liquid steel commonly takes place during Al deoxidization process and the extent of clustering significantly influences steel cleanliness. The clustering is suggested to have a close relationship with the interfacial properties of alumina inclusions and liquid steel. In the present work, the effect of the interfacial properties on the clustering of alumina inclusions was investigated. Different amounts of Te were added to molten iron before Al deoxidization at 1873K to modify the interfacial properties. A method was developed to analyze alumina clustering, such as the mean diameter, the clustering degree and the average number of particles per cluster. The values of these parameters were found to increase with increasing Te addition up to 200ppm, thereafter to decrease with further Te addition. The effect of Te addition on the clustering of alumina inclusions is discussed with the theory of spontaneous cavitation between non-wetting surfaces. Te affects the clustering in two opposite ways. First, it decreases the surface tension of molten iron. This makes clustering less likely; Second, it makes alumina inclusions more faceted. This favors clustering. Due to the two opposite effects, the extent of alumina clustering reaches a maximum at 200ppm Te addition.