Effect of Electric Current Pulse on Solidification Microstructure of Hypereutectic High Chromium Cast Iron Cooling from the Temperature between Liquidus and Solidus

Abstract

In this paper, the solidification course of the hypereutectic High Chromium Cast Iron (HCCI) was treated by the Electric Current Pulse (ECP). Effects of treating time, initial temperature applying ECP and its parameters (voltage, frequency, pulse width) on the microstructure were researched. The results showed that the ECP can promote refining of primary and eutectic carbides significantly. As the result of strengthening role on the solute fluctuation by ECP, the larger effect of nucleation and refinement promoting of carbides was displayed at the initial temperature closer to the liquidus. The more obvious refinement effect was showed under longer treating time. Huge differences in microstructure were shown under different combination of the three ECP parameters. Some combinations promoted primary carbide refinement and eutectic carbide number reduce obviously, and fine granular primary carbides with the size of ~20μm could be obtained. Some other combinations led to a trend of eutectic carbide granulating.