Mechanisms and rate prediction modeling of corrosion fatigue crack propagation in 2050-T84 Al-Li alloy

Corrosion fatigue crack propagation behavior plays a critical role in determining the structural integrity and safe service life of aerospace components. This study systematically investigated the key factors influencing corrosion fatigue crack propagation in 2050-T84 Al–Li alloy, with particular emphasis on the roles of subgrains microstructure, corrosion product layers, stress ratio, and loading orientation. Within the subgrains, the presence of dislocations and cross-distributed precipitates induced localized stress concentration, thereby altering the trajectory of corrosion fatigue crack propagation. The dense corrosion pits within subgrains mitigated stress concentration at the crack tip, promoting crack deflection and subsequent crack closure. Corrosion product layers altered the electrochemical potential gradient between the alloy surface and the crack interior, directly affecting the anodic dissolution rate at the crack tip and consequently influencing the crack growth rate. Based on these insights, a predictive model for corrosion fatigue crack propagation was developed and validated against experimental data, demonstrating strong agreement between predicted and observed crack propagation behavior.