Plasma surface alloying of spheroidal graphite iron

Spheroidal graphite iron is chosen as a substrate material on which plasma WMo and NiCr surface alloying are carried out by the Xu-Tec process. The experimental results show that WMo surface alloying increases the surface hardness of the cast iron from approximately 200 to 1500 HV while NiCr alloying enhances the surface hardness to 600 HV or above and also the corrosion-resistance of the cast iron. The alloy content and hardness of the alloyed layer manifest a gradually decreasing tendency from surface to the inside of the substrate, an ideal profile which is beneficial to the cohesion of the surface modification layer with the bulk material. The microstructures, alloy contents and surface hardnesses of the alloyed layers are presented. Effects of processing conditions and carbon, silicon content of the specimens on the alloying results are also discussed.