Ennoblement of stainless steel in natural seawater – A new explanation

Abstract

The ennoblement of corrosion potential (E corr ) of passive metal immersed in seawater was investigated with electrochemical technology and epifluorescence microscopy. The in situ observation showed that the bacteria number increased on the metal surface according to an exponential law which was in the same way with the ennoblement of E corr . At the same time, the anodic polarization current of high-Mo stainless steel decreased in the initial days. According to the mix-potential theory and the characteristics of polarization curves of high-Mo steel in natural seawater, the ennoblement of corrosion potential may be induced by the decrease of the passive current density.