Investigation of the Pitting Corrosion Behavior of 403 Martensitic Stainless Steel in Bromide and Iodide Solutions

In this study, the pitting corrosion behavior of 403 martensitic stainless steel was investigated in NaBr and NaI solutions, by using potentiodynamic and potentiostatic techniques. The observations showed that halide ions have a bilinear effect on the pitting corrosion. The bromide ion due to its smaller ionic radius is more active in the initiation step of metastable pits, so that it increases the frequency of occurrence of metastable pits. On the other hand, the iodide ion has a greater effect on the propagation step, due to the low acidity of HI. Altogether, the bromide ion is more aggressive than iodide and has a lower pitting potential.