7075铝合金在不同温度盐水环境中的腐蚀疲劳行为
收稿日期: 2014-04-16
修回日期: 2014-06-09
网络出版日期: 2014-07-17
基金资助
国家自然科学基金（51101010）
Corrosion Fatigue Behavior of 7075 Aluminum Alloy in Saline Water Environment at Different Temperatures
Received date: 2014-04-16
Revised date: 2014-06-09
Online published: 2014-07-17
Supported by
National Natural Science Foundation of China (51101010)
基于飞机结构材料7075铝合金在沿海地区服役时海水飞溅及曝晒导致的高温腐蚀疲劳损伤问题，研究了7075铝合金在35，55，75 ℃下3.5% NaCl溶液环境中的腐蚀疲劳寿命，并使用扫描电子显微镜（SEM）观察断口形貌，探讨了温度对腐蚀疲劳裂纹萌生扩展的影响机理。结果表明：同一应力水平下，温度越高，腐蚀疲劳寿命越短，300 MPa时35，55，75 ℃下的中值寿命分别为33 001，30 931，15 346次循环。腐蚀损伤和疲劳损伤存在竞争关系，应力水平较高时，腐蚀较轻，试样寿命主要受应力水平影响，疲劳源多从铝合金基体与包铝层结合处萌生；应力水平较低时，腐蚀较严重，疲劳寿命随温度升高明显下降，疲劳源多从腐蚀坑处萌生。断口形貌显示高温环境主要通过加速腐蚀坑的形成来影响疲劳源的萌生，深坑状腐蚀坑应力集中严重，对疲劳性能伤害大。
刘轩 , 刘慧丛 , 李卫平 , 叶序彬 , 朱立群 . 7075铝合金在不同温度盐水环境中的腐蚀疲劳行为[J]. 航空学报, 2014 , 35(10) : 2850 -2856 . DOI: 10.7527/S1000-6893.2014.0155
Based on high-temperature corrosion fatigue injury problems caused by seawater splash and insolation when aircraft structure material 7075 aluminum alloy servicing at coastal area, the corrosion fatigue life of 7075 aluminum alloy in 35, 55, 75 ℃, 3.5% NaCl saline water is studied by corrosion fatigue life test, and the influence of temperature on corrosion fatigue crack initiation and propagation is discussed by fracture morphology observation using scanning electron microscope (SEM). The results indicate that at the same stress level, corrosion fatigue life decreases with the temperature rising, such as the median fatigue life is respectively 33 001, 30 931, 15 346 cycles while temperature is 35, 55, 75 ℃ at the stress of 300 MPa. There is a competitive relationship between corrosion damage and fatigue damage. When at high stress level, corrosion damage is slight and fatigue damage is the main influencing factor of fatigue life; fatigue source usually initiates from the interface between matrix and Al clad. When the stress level is low, corrosion damage gets severe and fatigue life declines sharply with the temperature rising; fatigue source usually initiates from corrosion pitting. Fracture morphology shows that high-temperature environment influences initiation of fatigue source mainly by accelerating the formation of corrosion pitting, and pitting with deep hole shape is often accompanied by severe stress concentration which does great damage to fatigue property.
Key words： 7075 aluminum alloy; corrosion fatigue; temperature; saline water; pitting
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