Corrosion Behaviors of Fe-22Cr-16Mn-0.55N High-Nitrogen Austenitic Stainless Steel in 3.5% NaCl Solution

In this study, the corrosion behavior of the high-nitrogen austenitic stainless steel (HNS) Fe-22Cr-16Mn-0.55N before and after solution treatment (ST) in 3.5% NaCl solution has been investigated. The effect of a solution temperature of 1100 °C and heat preservation for 30 min on the corrosion resistance and passive film protection of HNS steel was studied. Open-circuit potential, potentiodynamic polarization and electrochemical impedance tests were used to assess the corrosion resistance of treated and untreated steels. In addition, potentiostatic polarization and XPS techniques together with Mott–Schottky curves were applied to determine the composition and properties of the passive films. The results showed that after solution treatment, the grain size of HNS decreased and the grain became more uniform. Although corrosion occurred on HNSs both before and after treatment, solution treatment resulted in greater compactness in passive films, leading to lower carrier density, lower corrosion current density and better corrosion resistance.