Liquid and solid inclusions at advancing steel solidification fronts

In this paper, the behavior of liquid and solid inclusions at advancing planar and cellular solid fronts during the solidification of steels was investigated through in situ visualization with a confocal scanning laser microscope. In the case of the liquid spherical Al₂O₃-CaO-MgO inclusions, theoretical prediction models agree with the experimental observations with respect to the critical front velocity required for engulfment. For the irregular solid Al₂O₃ inclusions, the prediction models underestimate the critical velocities. At very low growth velocities, the inclusions were found to slide along the front and get entrapped in the intercellular regions. Once entrapped, it was found that liquid inclusions appeared to be more readily engulfed at the intercellular regions than at the planar fronts. This was not observed for the large solid inclusion clusters.