Investigation on multi-element Ni-Cr-Mo-Cu alloying layer by double glow plasma alloying technique

This paper describes an investigation of double glow surface alloying of low-carbon steel with Hastelloy C-2000 nickel-based surperalloy. Emphasis is placed on the effect of the source electrode voltage, cathode voltage, working pressure and parallel distance between source electrode and cathode on the chemical composition and physical qualities of surface alloying layer. The results show that the total content of alloy elements, thickness of alloying layer and absorbing alloy element rate have closely related with technological parameters. The combination of SEM and XRD is used to investigate morphology and structure of the multi-element Ni-Cr-Mo-Cu surface alloying layer. The thermodynamic calculation was performed to predict the mole fraction of phase in the alloying layer as function of temperature. The calculated results is in agreement with the observation of microstructure of alloying layer. The corrosion experimental results indicated that the corrosion resistance of alloying layer formed on the stainless steel was super to that of alloying layer formed on the low-carbon steel.