Effect of Plastic Deformation on Pitting Mechanism of SS304

Localized corrosion induced by plastic deformation has been reported for many alloys used in structural and functional applications. To understand the interplay of plastic deformation and pitting corrosion, samples of stainless steel 304 were subjected to different levels of plastic tensile strain and their corrosion behavior was studied. Plastic deformation is believed to alter materials' surface condition, hence deteriorating the pitting resistance of materials. Results from this study suggest that in situ plastic deformation from 0.1 to 9 pct decreases the pitting potential of SS 304 to a similar level. Upon releasing the stress, slip steps formed at the metal surface due to plastic deformation contribute to the decrease in the pitting resistance of SS 304. Residual strain hinders pit repassivation to a minor extent. Results from electrochemical tests on samples with different levels of plastic strain are discussed in this paper.