3．5％NaCl溶液对铝合金疲劳裂纹扩展特性的影响

INFLUENCE OF 3.5%NaCl ON FATIGUE CRACK GROWTH BEHAVIOR IN ALUMINUM ALLOY 7050-T7451

对高强铝合金７０５０—Ｔ７４５１在模拟海水（３．５％ＮａＣｌ溶液）的疲劳裂纹扩展特性进行了试验研究结果表明，３．５％ＮａＣｌ溶液加速了７０５０—Ｔ７４５１铝合金的疲劳裂纹扩展速率ｄａ／ｄＮ．考虑应力比影响的有效应力强度因子面ΔＫｅｆＴ可以满意地表征不同环境中的的ｄａ／ｄＮ．裂纹面上的腐蚀产物较薄，对疲劳裂纹闭合的影响可以忽略不计．

The corrosion fatigue crack growth behavior of aluminum alloy 7050-T7451 has been studied in 3.5% NaCl solution and at frequencies of 1 and 10 Hi at stress ratios of 0.5,0.06 and 1.The results showed that the fatigue crack growth rate(FCGR)in 3.5% NaCI solution is higher than that in air.FCGR for all test conditions were well correlated with ΔKeff derived from the equation based on crack closure theory proposed by Schijive. This implys that crack closure effect is negligible,in fact,the thickness of corrosion product on crack surface measured by Auger spectroscopy was thinner.