Effect of electric current pulses on grain size in castings

The effect of electric current pulses (ECP) on grain size in castings is considered. The relationship between grain size and electric current density is revealed. Numerical calculation shows that an electric current density with a magnitude of 10(3) A/cm(2) is needed to reduce the grain size by one order of magnitude for some pure metals, such as Ni, Sn, Pb, Cu, and Fe. The effects of Joule heating, skin, and pinch force are proved to be of lesser importance. The theory gives a good explanation for the experimental results reported by Conrad and co-workers.