Early Stages of Microbiologically Influenced Corrosion in Marine Environments – Surface Roughness Effects

Abstract Microorganisms can influence the corrosion of metallic materials through a phenomenon known as microbiologically influenced corrosion (MIC). MIC can increase corrosion rates of metallic alloys in corrosive environments, e.g., salt-water corrosion in marine infrastructure, thereby reducing the service life of these alloys. The objective of this study was to determine whether the surface roughness of an alloy has a significant effect on its corrosion resistance in the presence of microorganisms. Test coupons of marine-grade carbon steels and stainless steels (UNS G10180, UNS S30400 and UNS S31603) were ground to multiple finishes (80 grit, 600 grit and 0.05 μm) to achieve various surface roughnesses. The cylindrical test coupons were immersed in biologically active seawater off the coast of Southern California. The mass differences between pre-and post-corroded coupons were recorded and the corrosion rates were determined using the ASTM G1-03 (2017) standard. Post-test coupons were examined using optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS).