Agglomeration Characteristics of Various Inclusions in Al-killed Molten Steel Containing Rare Earth Element

The nozzle-clogging problem is closely related to the agglomeration behavior of inclusions in steel-containing rare earth (RE). The present study first optimized the thermodynamic model by supplementing thermodynamic data of the RE compound to study the formation of various inclusions in the Ce-Al-O-S system. Based on that, laboratory-scale experiments with different Ce and Al contents were designed to obtain samples containing a single type of inclusions, viz., Al₂O₃, Ce-Al-O, Ce₂O₃, and Ce-O-S, respectively. Additionally, the agglomeration behavior of inclusions was observed in situ by confocal laser scanning microscopy (CLSM), and the calculated attractive forces were used to compare the agglomeration tendency of the four inclusions. The results show that the agglomeration of Al₂O₃ inclusions is attributed to the strongest attractive force (1.0 × 10⁻¹⁵N to 3.0 × 10⁻¹⁴N) among the four kinds of inclusions. Although Ce-Al-O and Ce₂O₃ inclusions have the weaker attractive forces (1.3 × 10⁻¹⁶N to 2.0 × 10⁻¹⁴N), they can also agglomerate together and form large-sized clusters. The attractive forces between Ce-O-S inclusions are the weakest (2.1 × 10⁻¹⁸N to 6.0 × 10⁻¹⁶N), that is, this kind of inclusion is more difficult to agglomerate than other inclusions. The study can provide theoretical support for improving the nozzle-clogging problem of RE-containing steel from the inclusion-controlling perspective.