Effect of electric current pulse parameters on the solidification microstructure of hypereutectic high-chromium cast iron near-liquidus melted

Solidification of hypereutectic high-chromium cast iron samples near-liquidus melted was treated with electric current pulse (ECP). The effects of ECP parameters such as electric voltage and pulse frequency on the solidification microstructure were investigated during the treatment. It is found that increasing the pulse frequency or electric voltage is helpful to carbide refinement and granulation in the cast iron. The increase of pulse frequency promotes the precipitating of a large number of fine granular primary carbides and the occurrence of a divorced eutectic reaction, which lead to the decrease in number of lamellar eutectic carbides. The increase of electric voltage contributes to the primary carbides refining and granulating as well as the lamellar eutectic carbides shortening. An excessive voltage value can also be favorable to the occurrence of a divorced eutectic reaction and the formation of additional primary carbides.