MODELING THE BEHAVIOR OF AL2O3 INCLUSIONS DURING THE DENDRITIC SOLIDIFICATION OF STEEL

Starting with a distribution of single-particle alumina inclusions, es timates of their collision frequencies and the number concentrations o f two-and three-particle clusters in the interdendritic liquid during solidification were made. The alumina clusters possibly serve as pore- nucleation sites, so their number concentrations that form during soli dification are of interest. We also show that the smaller alumina incl usions are not entrapped in the dendritic solid during solidification, based on estimates of the interdendritic solidification rates and emp irical data on the engulfment of Al2O3 inclusions by solidifying steel . Engulfment by the interdendritic liquid, however, is enhanced by the gradients of the concentrations of oxygen and sulfur in the interdend ritic liquid during solidification. These elements are surface active on the liquid-steel/alumina interface and, in turn, introduce very str ong capillary forces on the interdendritic alumina inclusions.