Transient simulation of multi-physical field evolution in Fe–0.2C–6Cu alloy under pulsed and differential-phase magnetic fields

Abstract

A transient 2D axisymmetric mathematical model that couples the pulse electromagnetic field with fluid flow and solidification was established by using the COMSOL Multiphysics software. The solidification behavior of Fe–0.2C–6Cu wt.% alloy during direct chill (DC) casting was first comparatively analyzed under conditions with and without the application of a pulsed magnetic field. Particular attention was paid to the evolution of melt flow, heat transfer, and solidification characteristics at various spatial locations. Subsequently, the coupled effects of pulsed electromagnetic parameters—including current intensity, frequency, and duty cycle—on the flow, thermal, solidification behavior, and mechanical response of the alloy were systematically investigated. The results demonstrate that optimized pulsed magnetic field (PMF) and differential-phase pulsed magnetic field (DPMF) conditions significantly enhance the Lorentz force, inducing strong and stable toroidal vortex structures. This in turn intensifies convective heat transfer and accelerates the solidification rate. Among the tested conditions, the combination of a 1200 A current and a frequency of 10 Hz yielded the most favorable electromagnetic response. Mechanical analyses further indicated that enhanced strain compatibility and stress redistribution capabilities were observed at critical interface regions under DPMF conditions, highlighting the potential of DPMF to tailor solidification microstructures and mitigate the development of residual stresses during DC casting.