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据飞机结构损伤容限设计的要求、进行了模拟海水（３．５％ＮａＣｌ溶液）对高强铝合金７０５０－Ｔ７４５１疲劳裂纹扩展特性影响的试验研究。结果表明，３．５％溶液中的Ｃｌ￣－加速了７０５０－Ｔ７５４１铝合金的疲劳裂纹扩展速率ｄａ／ｄＮ。在３×１０￣（－４）ｍｍ／ｃｙｃｌｅ以下，横向ｄａ／ｄＮ略高于纵向ｄａ／ｄＮ：在３×１０（－４）ｍｍ／ｃｙｃｌｅ以上，横向ｄａ／ｄＮ明显高于纵向ｄａ／ｄＮ。考虑应力比影响的有效应力强度因子ΔＫ＿（ｅｆｆ）可以满意地表征不同环境中的ｄａ／ｄＮ。裂纹面上的腐蚀产物很薄，对疲劳裂纹闭合的影响可以忽略不计。１至１０Ｈｚ范围内的试验频率对３．５％ＮａＣｌ溶液中的ｄａ／ｄＮ几乎没有什么影响。
According to the requirements of the damage tolerance design of aircraft structure, the experimental study on the effect of simulated seawater (3.5% NaCl solution) on the fatigue crack propagation properties of high strength aluminum alloy 7050-T7451 was carried out. The results show that 3.5% solution of Cl ~ - accelerated 7050-T7541 aluminum alloy fatigue crack growth rate da / dN. Below 3 × 10 -4 mm / cycle, horizontal da / dN is slightly above vertical da / dN: Above 3 × 10 (-4) mm / cycle, horizontal da / dN is significantly higher than vertical da / dN . The effective stress intensity factor, ΔK eff, which takes into account the effect of stress ratio, can satisfactorily characterize da / dN in different environments. The corrosion product on the cracked surface is very thin and the effect on the fatigue crack closure is negligible. The test frequency in the range of 1 to 10 Hz has little effect on the da / dN in 3.5% NaCl solution.