Transient Simulation of Nitrogen Absorption and Redistribution During Pressurized Electroslag Remelting (PESR)

This study presents a multiphysics numerical model that simulates nitrogen alloying during the pressurized electroslag remelting (PESR) process for high-nitrogen stainless steel. The primary objective was to understand nitrogen absorption mechanisms and redistribution within the melt during ingot growth. By coupling magnetohydrodynamic (MHD) flow, heat transfer, solidification, and species transport, we explored two additive feeding strategies—continuous and interrupted—and their effects on nitrogen distribution. Results indicate that the interaction between the interfacial nitrogen transfer rate and convective mixing is pivotal in governing nitrogen transport. Specifically, Lorentz-force-driven recirculation enhances nitrogen dissolution and lateral transport in the slag, while buoyancy-driven convection in the molten metal controls redistribution prior to solidification. Continuous feeding strategies significantly increase nitrogen uptake due to sustained concentration gradients at the slag-metal interface. In contrast, interrupted feeding promotes partial homogenization but limits final nitrogen absorption. Both strategies reveal that incomplete mixing before solidification leads to spatial variations in nitrogen concentrations. The findings were corroborated with experimental data, underscoring the effectiveness of the developed model in predicting nitrogen behavior during PESR.