(1. 华中科技大学化学与化工学院, 武汉 430074；
2. 中石油吉林油田采油工艺研究院，松原 131200；
3. 湖北文理学院化工与食品学院，襄阳 433500)
摘 要: 基于恒应变的C型环测试装置，采用电化学噪声(ECN)研究恒应变条件下AA7075高强铝合金在3%NaCl (质量分数)溶液中裂纹的萌生及发展过程。结果表明：伴随着裂纹的萌生和发展，出现明显的周期性电流与电位噪声峰，且这些噪声峰的出现频率和时间与3D显微镜所观测到的C型环试样表面裂纹的萌生与长大具有良好的一致性；裂纹的萌生与成长并不是连续发生的，而是表现出明显的阶段性；恒应变试验后期，随着C型环的应力松弛，裂纹的纵深延展几乎停止，但仍然可以捕捉到密集的短时电流噪声峰，这些噪声峰可能与裂纹侧壁的亚稳态点蚀生长过程有关。
关键字: 7075-T6铝合金；应力腐蚀开裂；裂纹萌生；电化学噪声
（1. School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology,
Wuhan 430074, China;
2. Production Technology Research Institute of Jilin Oilfield of Petro China, Songyuan 131200, China;
3. School of Chemical and Food Sciences, Hubei Institute of Arts, Xiangyang 433500, China）
Abstract:The initiation and propagation process of stress corrosion cracking of AA7075 high strength aluminium alloy were investigated by electrochemical noise in 3%NaCl (mass fraction) solution by a constant strain test device. The results show that the propagation of cracks can produce the intensive and regular potential and current noise peaks. In addition, the beginning time and frequency of noise peaks are consistent with the initiation and growth process of cracks via online 3D microscope observation. By the shape and lifespan analysis of noise peaks, the advance of cracks is an intermittent process obviously. The deepening process of crack is almost inhibited due to the relaxation of stress on the C-ring specimen. Meanwhile, the dense short-time noise peaks can be observed, which is possibly induced by the metastable pit corrosion along the crack mouth.
Key words: 7075-T6 aluminium alloy; stress corrosion cracking; crack initiation; electrochemical noise
