Microstructural characteristics of electric discharge alloyed layers on spheroidal graphite cast iron with different electrode materials

In this study, electrical discharge alloying (EDA) is used to modify the surface of ferritic spheroidal graphite cast iron. Under the conditions of fixed EDA parameters and variable elements (i.e., electrode materials Fe75 mass%Si, Al, Ni, Mg and Cr), these alloying elements are dissolved in substrate. Then, the effects of alloying with different alloying elements on the EDAed layers are investigated. Experimental results reveal that the Mg electrode has produced the thickest EDAed layer while the Cr electrode has produced a thinner layer. Additionally, EPMA/ mapping is also used to analyze the distribution of different elements in their respective EDAed layers and X-ray diffraction is used to analyze the phase compositions of these layers. The results of hardness tests reveal that the EDAed layer with Cr has the highest hardness value. This may be related to the formation of carbides that contain Cr in the layer.