Interpretation of Passive Current Maxima During Polarization of Stainless Steels

Abstract

The occurrence of passive current maxima during the anodic polarization of stainless steel in sulfuric acid solutions has been investigated using electrochemical and electron microprobe techniques. This phenomenon is caused by nickel enrichment on the surfaces of electrodes during pre-polarization immersion. Tests with various samples of stainless steels show that passive current maxima are not caused by sensitizing heat treatments. Therefore, contrary to other interpretations, a suitable evaluation method for predicting intergranular corrosion susceptibility cannot be based on anodic polarization measurements.