Grain Refinement by Pulse Electric Discharging and Undercooling Mechanism

High voltage durative discharge was applied to unidirectional solidifying pure aluminum by discharging capacitor bank. The conditions to modify solidification structures, including initial voltage and capacitance of capacitor bank, were examined. The experimental results showed that the solidification structure was modified from columnar grains to equiaxed grains by increasing initial voltage and capacitance. However, coarsening of grain structures was observed when the discharge energy poured from the capacitor bank was excessive. The effect of pulse electric discharge on undercooling during solidification was analyzed, and the grain structures were simulated using cellular automaton methods based on nucleation theory.