The stress concentration effect of different corrosion pits is different, the shapes of corrosion pits can be seen as semi-ellipsoidal, the short half axes、long half axes and depth of corrosion are 、 and , through finite element analyze, we can see that the stress concentration factors increase with the increase of , but the stress concentration factors decrease with the increase of .

The number of corrosion pits with different corrosion times were got through extracting the corrosion character of LY12CZ aluminum alloy based on binary image disposal technique, through statistical fractal theory we can see that the distribution of corrosion pits have fractal character; the fractal dimension and weight loss rate increased with the corrosion time and the change rule of fractal dimension with different corrosion time consistent with weight loss rate, both are accordant with power function, so the fractal dimension can be regarded as an important parameter to evaluate the corrosion degree.

The corrosion images of LY12CZ aluminum alloy with different corrosion time were obtained from accelerated corrosion experiment. The changing law of pits corrosion ratio at different corrosion time and corresponding corrosion grade were attained through image processing technique based on binary characteristic extraction. A new thought of corrosion damage evolvement law for aluminum alloy was proposed based on Corrosion grade which was regarded as the evaluation standard of corrosion damage for aluminum alloy.

This paper is to reveal the small crack growth law of 6A02 aluminum alloy specimen by SEM in-situ experiment. The Nisitani H. formula for crack propagation is modified by SEM in-situ experimental results. The effect of corrosion is emphasized in small crack growth law of 6A02 specimen by introducing of corrosive factors. The fitting curve between corrosive factors and corrosive time is revealed. It would provide a theoretical foundation for the corrosion fatigue damage of 6A02 aluminum alloy.

The relation between corrosion depth and width with corrosion time is according with the power function. The corrosion pits can be seen as ellipse balls through the examination of QUESTAR three-dimensional optics microscope. Corrosion can decrease the fatigue life of materials and is the main reason of fatigue crack form and grow; through AFGROW analyze we can see that the AFGROW software can simulate crack growth life well and the error is low, the crack growth life and critical crack length are conservative than experiment values.