Investigation on pitting resistance of Sn-containing ferritic stainless steel with solution simulation method

Abstract

In this study, Sn2+ solution simulation method is used to investigate the effect of Sn on pitting corrosion behavior of tin-containing ferritic stainless steel 430LX. It is found that the correlation between Epit and [Sn2+] is opposite to the correlation between critical potential temperature (CPT) and [Sn2+]. After potentiostatic polarization at a specific potential, the correlations become the same. The CPT experiment after a series of potentiostatic steps proves that Sn2+ exhibits positive influence only when the pH and potential is within a certain range. All the complicated phenomena can be explained by the under-potential deposition mechanism. SnO2 passivation film that enhances the corrosion resistance is only produced when under-potential deposition occurs.