针对2024-T62铝合金薄板系统地开展了腐蚀预损伤对材料疲劳S-N曲线、小裂纹萌生行为、长短疲劳裂纹扩展及物理小裂纹门槛值扩展行为的影响等试验研究。结果表明:腐蚀预损伤对材料疲劳S-N曲线及材料疲劳小裂纹萌生行为有明显的影响,但对材料长短裂纹扩展及物理小裂纹门槛值扩展行为没有明显的影响。通过假定腐蚀预损伤为初始小裂纹,基于断裂力学理论,利用FASTRAN3.9软件预测了含腐蚀预损伤材料的疲劳S-N曲线。研究发现,预测与试验结果吻合较好。当材料含有较大尺寸的腐蚀预损伤时,对其进行寿命预测可以不考虑小裂纹效应的复杂影响。

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.