Collision of Micro-sized Non-metallic Inclusions in Liquid Steel Flows: A Computational Study

The quality of steel is limited, among others, by the contained non-metallic inclusions. A key factor in this context is the growth of micro-sized indigenous inclusions. Those are assumed to form larger inclusions or clusters by collision in the turbulent melt flow. In this study, a numerical model is established to investigate the collision probability of spherical and clustered non-metallic inclusions in steel by discrete particle simulations. A strong dependence of the agglomeration probability from the particle sizes, form and shear rate in the process is observed. Larger particles are hampered to coagulate because of the significant influence of the lubrication force. Thus, the maximum particle size of spherical particles is limited, while clustered agglomerates can still grow. From the simulation results, models for the determination of the collision coefficient are deduced for spherical particles and non-spherical particle clusters.