The study of grain transport effects on grain refinement under pulsed magnetic fields

The motion of grains within the molten metal under a pulsed magnetic field influences the influx of grains, thereby impacting the refinement of the solidification structure of metal. Physical simulation experiments, solidification studies, numerical simulations, and theoretical analyses are combined to investigate the motion patterns of grains in molten metal subjected to a pulsed magnetic field in the case of identical power. The findings suggest that grain movement occurs in two primary phases: initially, within the non-flow area at the solid-liquid interface, where grains respond to electromagnetic forces, and subsequently, within the flow area where the molten metal carries the grains. The speed of grain transport in the flow area directly influences the movement of grains in the non-flow area, then affecting the refinement of the metal solidification structure. The study introduces the concept of "transport characteristic time" to quantify the transport capacity of grains within the flow area, which enables a quantitative analysis of refinement effect under identical power conditions.