Corrosion behavior of high nitrogen austenitic stainless steel in the solutions containing different F^- concentration

Stainless steels are attractive due to its high strength, high chemical stability, low gas permeability and wide selection of alloys. However, stainless steels are prone to corrosion where SO4^2- and F^- are released from the membrane in the PEFCs, which, as a result, will shorten the age of the bipolar plates and exert a negative influence on the function of the cells. Therefore, great attention is given on high-nitrogen austenitic stainless steels (HNASS) which have lower costs and good localized corrosion resistance. The effects of the different F- concentration on the corrosion behavior in the high nitrogen austenitic stain steel were investigated through polarization curve measurement and electrochemical impedance spectroscopy. The results show that the corrosion resistance of the experimental steel is the best in the 0.05 mol/L SO42- (pH 5.5) + 2 ppm F- solution. As the F- concentration increases, the passivation film of the experimental steel becomes thicker and denser, leading to stronger corrosion resistance.