Effect of plasma nitriding at low temperature on the corrosion resistance and conductivity of 2205 duplex stainless steel

A nitrogen expanded austenite (γN) layer with a thickness of 3 μm was prepared by plasma nitriding of 2205 duplex stainless steel (DSS) at 460°C for 1 h with hollow cathode discharge assistance. The microstructure and phase composition of nitrided specimens were examined. The electrical conductivity of nitrided samples was measured before and after the corrosion test, respectively. The corrosion current density of nitrided 2205 DSS polarized for 4 h was 1.3 μA cm−2 (at 0.6 V) and −1.4 μA cm−2 (at −0.1 V), respectively. The interfacial contact resistance (ICR) of the nitrided 2205 was 14.7 mΩ cm2 which was much lower than that of bare 2205 DSS substrate (93.6 mΩ cm2) after 4 h potentiostatic polarization at cathodic conditions. The corrosion resistance and electrical conductivity were evidently improved compared with 2205 DSS substrate.