Effect of the electrochemically induced surface annealing on corrosion behaviors of 304L stainless steel in an acidic environment

Abstract

The corrosion behaviour of electrochemically induced surface annealed (EISA) 304L stainless steel was analysed using a range of electrochemical methods, such as polarisation, impedance and Mott-Schottky techniques. Secondary ion mass spectroscopy was used to examine the elemental distribution around the surface of an EISA-treated specimen. The results showed that the EISA treatment increases the resistance to pitting corrosion due to surface densification caused by the absorption of NO and/or N 2 , which had been reduced under cathodic polarisation during the EISA process. Owing to the limited annealing depth, however, the prolonged corrosion process (i.e. Fe dissolution) can lead to the dissolution of NO and/or N 2 species, which had been absorbed on the outer surface, and only smaller portions remained with an uneven distribution at the surface. This can make the EISA-treated steel more vulnerable to corrosion.