Early Stages of Microbiologically Influenced Corrosion in Marine Environments - Surface Roughness Effects
- Grazziela Sena (California State Polytechnic University) | John Fly (California State Polytechnic University) | Neelam Patel (California State Polytechnic University) | Vilupanur A. Ravi (California State Polytechnic University)
- Document ID
- NACE International
- CORROSION 2019, 24-28 March, Nashville, Tennessee, USA
- Publication Date
- Document Type
- Conference Paper
- 2019. NACE International
- steel, MIC, microbial, biofilm, microorganisms
- 1 in the last 30 days
- 4 since 2007
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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).
Marine infrastructure, including bridges, offshore platforms, pipelines, tanks, etc., are especially susceptible to corrosion because of the high salt content of the environment.1 Marine-grade alloys have been developed to prolong the life of these structures in these environments. However, the presence of microorganisms can reduce the lifespan of these structural materials. Microbiologically influenced corrosion (MIC) is the corrosion of a metal or alloy induced by microbial communities indigenous to the prevailing environmental conditions.2 There are many organisms that can induce this form of corrosion, but a few of the most significant would be acid-producing, iron-reducing and sulfate-reducing bacteria. Causative organisms include those of both aerobic and anaerobic nature. Studies have shown that surface topography is one of the parameters that influence bacteria adhesion.3 The study was aimed at determining whether the surface roughness of an alloy has a significant effect on its corrosion resistance in the presence of microorganisms.
Coupons of three different grades, UNS G10180, UNS S30400 and UNS S31603, were metallographically prepared to three different surface finishes (80 grit, 600 grit, and 0.05 μm) and exposed to a natural seawater environment.
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