<p>The aluminum content in 16MnNiV steel is strongly affected by redox reactions at the slag–metal interface during electroslag remelting (ESR). To describe the Al transfer behavior, a transient three-dimensional (3D) multiphysics model was developed by coupling the electromagnetic field, two-phase flow, heat transfer, species transport, and multi-component interfacial reactions. The electromagnetic field was solved using the magnetic vector potential formulation, and the resulting Lorentz force and Joule heating were introduced into the momentum and energy equations. The Volume of Fluid method was used to capture the evolution of metal droplets and the slag–metal interface. Interfacial reactions involving Al, Mn, Si, O, FeO, Al₂O₃, MnO, and SiO₂ were incorporated based on thermodynamic equilibrium data and diffusion-controlled mass transfer in both the metal and slag phases. The predicted Al, Mn, and Si contents in the remelted ingot agree well with the experimental measurements, confirming the capability of the model to describe element transfer under coupled magnetohydrodynamic flow and heat transfer conditions. The results show that the average Al content in the ingot increases with increasing current. At 6000 and 7000 A, the average Al contents are 0.0380 and 0.0397 wt pct, respectively, which are lower than the initial value of 0.0400 wt pct, indicating Al depletion due to oxidation. By contrast, at 8000, 9000, and 10000 A, the average Al contents increase to 0.0404, 0.0425, and 0.0442 wt pct, respectively. This indicates that increasing the current suppresses Al oxidation loss and promotes Al enrichment during ESR. The enhanced Al retention is attributed to the combined effects of intensified Joule heating, modified slag–metal flow, and changes in the interfacial reaction balance.</p>