Inclusion Transfer Phenomenon under Unsteady Multiphase Flow during Rheinstahl–Heraeus Vacuum Treatment Process

Abstract

Inclusion particles are extremely harmful to the quality of steel products, and Rheinstahl–Heraeus (RH) vacuum treatment is the key process to remove the inclusions from molten steel. By coupling analyzing the unsteady gas–liquid flow and decarbonization reaction, the inclusion mass/population conservation model is developed to explore the inclusion particles transfer phenomenon during RH vacuum treatment process. The coupling mathematical models are validated by the metallurgical experimental data. The results show that the predicted inclusion mass concentration in unsteady CO–Ar–molten steel multiphase system has significantly smaller relative error than that in steady Ar–molten steel flow. CO bubble plays a key role in the inclusion transfer phenomenon, which prompts the inclusion transport, the collision-aggregation, and the removal process. At the 4th minute of vacuum treatment, the average inclusion volume concentration and the average inclusion number density in CO–Ar–molten steel are 72.75% and 64.62% of those in Ar–molten steel, respectively. The average inclusion characteristic radius in CO–Ar–molten steel is 7.33% larger than that in Ar–molten steel.