Aiming at the fatigue fracture problem of light Al-Li alloy in service environment, the third generation aluminum-lithium alloy 2195-T8 was taken as the research object. Experimental and simulation of the fatigue crack propagation behavior of the third-generation 2195-T8 Al-Li alloy with defects was investigated by constant amplitude tensile fatigue test and equivalent crack model. The results show that the fatigue crack starts at the bottom of the defect, and the crack growth rate is the fastest in the surface length direction, but the slowest in the depth direction. The fatigue fracture of 2195-T8 aluminum-lithium alloy has a typical delamination phenomenon, and the delamination of alloy greatly hinds the crack tip depth direction expansion, resulting in crack bifurcation. After the crack bifurcation, the propagation rate increases sharply, and the plastic region volume at the tip increases rapidly, which makes the alloy enter the rapid fracture zone. The above results show that the fatigue life of 2195-T8 Al-Li alloy with defects is reduced by crack propagation inclination and delamination.

This paper experimentally studied the stress corrosion behavior of 2195-T8 Al-Li alloys with prefabricated pits in 30vol% HNO₃. The microstructure was observed and determined by the scanning electron microscopy and the transmission electron microscopy. The typical corrosion features, i.e., regular or irregular corrosion pits and sub/intergranular corrosion, were investigated, and the role of stress were analyzed. The statistical results of the number and area of corrosion pits in various sizes were studied using an improved image processing method. Experimental results demonstrate that stress affects the intergranular corrosion or sub-intergranular corrosion of the alloy most, and promotes them to evolve into cracks under stress corrosion. Stress also plays a role in accelerating corrosion severity of certain corrosion feature. The number of corrosion pits with an area of 0–50 μm² can be seen as an index to reflect the degree of corrosion. Besides, a corrosion phenomenon, i.e., the pit bottom in the site with the maximum stress locally suffering from no severe corrosion, was observed and discussed.