Abstract: Fatigue fracture usually happens in service process because of the corrosion damage for aerospace aluminum alloy. The effect of pre-corrosion damage on the fatigue life of 2xxx aluminum alloy without clad layers under different stress ratio was studied using stereo microscope， SEM and fatigue tests. The affecting mechanism of pre-corrosion damage on the initiation and propagation of fatigue crack was also discussed. The results show that pre-corrosion damage has a significant effect on the fatigue performance， i.e. fatigue strength decreases with the increase of pre-corrosion extent. A C-T-R effect model of pre-corrosion defect on the fatigue limit was proposed. The fatigue limit effect factor C increases with the increase of pre-corrosion time or stress ratio R. Fracture analysis shows that the pre-corroded damage would result in the emergence of crack changing from single source to multiple sources and the crack initiation life would decrease because of the pre-corroded damage.

Key words: aluminum alloy, pre-corrosion damage, corrosion pit, fatigue life, C-T-R model, fracture analysis