Effects of micro-scale corrosion damage features and local microstructure on fatigue crack initiation location

The fatigue resistance of aerospace structures is degraded by the presence corrosion damage. This work characterizes micro-scale (<50 µm) morphologies and underlying microstructure AA7050 that impact crack formation. Corroded specimens were cycled to failure using a fracture surface marking spectrum. Pre-test characterization, fractography EBSD performed. No damage or metric independently correlates location initiation from corroded surfaces. However, there modest correlation between grain initiates grains have high misorientation angle with respect adjacent grains.