Susceptibility of 5xxx Aluminum Alloys to Localized Corrosion in Natural Waters

Future ship designs and modernization of existing platforms rely on lightweight Al, particularly 5xxx series Al-Mg alloys. Fatigue damage, stress corrosion cracking and microstructure instability are the major degradation mechanisms for ship structures. It is our hypothesis that microorganisms can control the rate and mechanism of degradation for 5xxx Al. Field and laboratory testing will be designed to answer the following questions related to aqueous corrosion: 1) Can naturally occurring microorganisms influence pitting and/or crevice corrosion in 5xxx Al? 2) Are microorganisms attracted to anodic sites and does their presence stabilize localized corrosion propagation?  3) Does degree of sensitization influence biofouling and its effect on open circuit potential?