关键词: 预腐蚀损伤, 疲劳, 小裂纹行为, 长裂纹扩展, 寿命预测, 铝合金

Abstract: This article reports an experimental study on the effect of pre-corrosive pit damage on the fatigue S-N curve, ini-tiation behavior of small crack, the growth behavior of small and large cracks, and the threshold growth behavior of small physical cracks of an aluminum alloy sheet 2024-T62. The results show that an obvious effect of the pre-corrosive pit damage is found on the fatigue S-N curve and the initiation behavior of small cracks. However, the effect of the pre-corrosive pit damage is not apparent on the growth behavior of both small and large cracks and the threshold growth behavior of small physical cracks. By assuming a pre-corrosive pit as an initiating surface small crack, and based on fracture mechanics, the fatigue S-N curves of the corroded aluminum alloy with different prior corrosions are predicted by using the commercial software FASTRAN3.9. The predictions are found to agree reasonably well with test results. In particular, it is found that the complex small crack effect can be neglected while predicting the aluminum alloy corroded with a big pre-corrosive pit damage.

Key words: pre-corrosive damage, fatigue, small crack behavior, large crack growth, life prediction, aluminum alloy