Electrochemical and fractographic analysis of Microbiologically Assisted Stress Corrosion Cracking of carbon steel

• Shallow and wide pits were found in samples exposed to sulfidogenic environments.
• Lack of evidence for SCC failure mechanism in presence of microorganisms.
• Presence of bacteria may cause elevated weight loss when compared with sterile systems.
• EFM and OCP results provided insight and possible capability for corrosion monitoring.

This study was carried out to evaluate the effect of microorganisms on the corrosion behavior of carbon steel when exposed to mechanical axial stress. Open Circuit Potential (OCP) and Electrochemical Frequency Modulation (EFM) response were measured on the tensile specimens while applying a constant load in various environments inoculated with different sulfidogenic or iron reducing microorganisms. The fractographic analysis revealed a noticeable impact of the enriched environments on the topography of tensile specimens; however, after the tests were carried out, it was not possible to detect any indications of a Stress Corrosion Cracking (SCC) failure mechanism for the tensile specimens.