Agglomeration Behavior of Nonmetallic Particles on the Surface of Si‐Killed Liquid Steel Using HT‐CSLM: An In Situ Investigation

While extensive research has focused on the agglomeration of AlO inclusions in low‐carbon, Al‐killed steels, the behavior of non‐AlO inclusions in Si‐ and Si/Mn‐killed steels remains poorly understood—despite their widespread industrial use and importance for steel cleanliness. This study investigates the in situ agglomeration of semisolid Al–silicate inclusions in Si‐killed steel using high‐temperature confocal scanning laser microscopy. Particle velocity, acceleration, and attractive forces at the steel/argon interface were measured directly. A modified capillary interaction model, based on the Kralchevsky–Paunov framework, was applied to calculate interparticle forces and showed good agreement with experimental results. Compared to AlO inclusions in Al‐killed steel, Al–silicate inclusions exhibited significantly weaker attractive forces (10 to 10 N) and a shorter interaction range (∼34 µm), indicating a lower tendency to agglomerate. These findings highlight key differences in inclusion behavior between steel types and confirm the model's applicability to semisolid systems.