Non metallic inclusions in aluminium kil

This study investigates the presence and evolution of non-metallic inclusions in aluminium killed steels during ladle treatments. The objective is to characterize various inclusion morphologies and assess their impact on the steel quality. Methodologically, heats of medium and low carbon aluminium killed steels were sampled at short time intervals during the ladle process. Non-metallic inclusions extracted from the steel matrix were analyzed using scanning electron microscopy and energy dispersive spectrometry. The results revealed six distinct morphologies of inclusions: spherical, faceted, platelike, dendritic, clusters, and aggregates. Spherical inclusions were found to be the most abundant; however, clusters and aggregates formed shortly after aluminium addition and showed a continuous increase in size with higher holding times. Smaller inclusions, predominantly spherical and polyhedral shapes, demonstrated little evolution in size or composition. The study concludes that large inclusions contribute significantly to the oxide volume fraction, while smaller spherical inclusions mainly account for the number, thus necessitating further research into their formation and removal processes during ladle metallurgy in steelmaking. All findings provide insights that may improve quality control and inclusion management in the production of aluminium killed steels.