The Behavior of Al_2O_3-CaO Inclusions in Low-Carbon Al-Killed Steel During Solidification

摘要

The behavior of Al_2O_3-CaO inclusions in low-carbon aluminium-killed steel with calcium treatment during solidification was investigated under in situ CSLM observations, and it was found that: 1. During solidification, the Al_2O_3-CaO inclusions could get engulfed or pushed by the advancing solidification front, depend on the δ-ferrite growth rate and the inclusion size. 2. A morphology change of pushed Al_2O_3-CaO inclusions from globular liquid to irregular solid was observed during solidification due to the partitioning of S and Al to the melt, which increases the potential of CaS precipitation. This CaS layer around the Al_2O_3-CaO core was found to be nonporous. 3. The inclusions after the morphology change had a trend of collision, agglomeration and cluster formation because of the presence of a strong attraction force between the solid inclusion pairs.