Effect of Temperature on the Corrosion Behaviour of Super Austenitic Stainless Steel S32654 in Polluted Phosphoric Acid

Abstract

The effect of temperature on the corrosion behaviour of super austenitic stainless steel S32654 in polluted phosphoric acid was evaluated using open circuit potential monitoring, potentiodynamic polarization, potentiostatic polarization, electrochemical impedance spectroscopy and Mott-Schottky analysis. The open circuit potential, corrosion potential and passive current density all increase significantly, and the pitting potential decreases with increasing temperature. The induction period of pits is shortened with increasing temperature. Increasing temperature also promotes the dissolution of MnS inclusion and the metal matrix. EIS results reveal that the protection of passive film is predominantly attributed to the barrier film, and the passive film becomes more porous and less protective at higher temperatures. The passive film presents a bilayer structure and behaves as an n-type semiconductor and it becomes more defective at higher temperatures.