Impact of AC Frequency and Slag Composition on Inclusion Entrapment in Electroslag Remelting

A transient numerical model is developed to investigate the influence of AC frequency and slag properties on the transport and entrapment of exogenous and endogenous nonmetallic inclusions (NMIs) during electroslag remelting. The model simulates the remelting of a 500 mm diameter consumable electrode into a 750 mm diameter ingot by coupling electromagnetics, fluid flow, heat transfer, solidification, dynamic ingot growth, and Lagrangian inclusion transport. The results show that thermal buoyancy dominates melt flow in the steel, while the combined effects of the Lorentz force and slag‐induced momentum transfer generate a localized secondary electro‐vortex beneath the slag–metal interface that strongly influences inclusion transport and residence time. Exogenous NMIs preferentially accumulate near the ingot periphery, whereas small endogenous NMIs remain suspended for longer periods, resulting in a more uniform radial distribution. Reducing the AC frequency from 50 to 1 Hz or replacing the CAF ₆ slag with CAF ₄ weakens the secondary vortex, producing a slightly shallower melt pool, increasing inclusion residence time, and promoting a more uniform NMI distribution throughout the ingot. Model predictions are validated against experimental measurements of the melt pool geometry and radial NMI distribution.