Multiple fatigue crack growth in pre-corroded 2024-T3 aluminum

Previous studies of fatigue crack growth in corroded aluminum have revealed that multiple crack-nucleating corrosion features often lead to the failure of individual test specimens. In the present work, this phenomenon was explored by performing quantitative fractography on forty 2024-T3 sheet aluminum fatigue specimens. Slightly over half of the specimens were found to have two or more crack-nucleating pits. The number of nucleating pits per specimen was found to be positively correlated with stress level, and an interactive effect with corrosion exposure duration was observed. A fracture mechanics-based model was developed to simulate the observed multiple crack growth process. Flaw interaction effects were investigated and the importance of modeling multiple crack growth at high stress levels was seen.