Corrosion behaviour of 2205 duplex stainless steel in marine conditions containing Erythrobacter pelagi bacteria

Abstract

A study was carried on 2205 duplex stainless steel immersed in synthetic seawater with Erythrobacter pelagi bacteria for a period of time up to 63 days. Electrochemical tests and microorganism growth analysis from SEM images was used for the study. The observation showed that biofilm developed on DSS 2205 surface retarded corrosion activities at the commencing stages of the study. With increase in immersion period, the biofilm grew thicker and the corrosion rate slightly reduced. Biofilm growth and later sloughing off, and also deterioration of the solution environment and the biofilm (“presence of micro cracks”), led to an increase in corrosion rate. This was seen after a long duration of exposure (up to 56 days).From electrochemical analysis, polarization plots showed movement towards the negative and a rise in current densities accompanied with decreased impedance values. SEM images showed cracked biofilm coating after a longer period of exposure in synthetic seawater. It was concluded that corrosion activities were hindered as long as the biofilm was intact. Any deteriorations on the biofilm accelerated formation of localized corrosion sites.