Electrochemical Corrosion Behaviour of Duplex Stainless Steels in Simulated Body Fluids

The electrochemical behaviour of three duplex stainless steels, (SAF 2101, SAF 2304, SAF 2205) was investigated. Open circuit potential, EOC, measurements, and electrochemical impedance spectroscopy (EIS) were employed both in phosphate-buffered saline solution (PBS, pH = 7.2) and in PBS simulating in vitro inflammatory conditions (PBS + H2O2, pH = 5.0). It has been established that the tendency of the investigated steel materials towards corrosion decreases in the following order: SAF 2101 < SAF 2304 < SAF 2205 in both aggressive environments. The superior corrosion resistance exhibited by SAF 2205 is ascribed to the formation of a passive film with enhanced protective effectiveness than the one formed on SAF 2101 and SAF 2304, and this improvement is ascribed to a synergistic effect of Mo + N owing to the high molybdenum content in the alloy.