(1. 華中科技大學(xué)化學(xué)與化工學(xué)院, 武漢 430074；
2. 中石油吉林油田采油工藝研究院，松原 131200；
3. 湖北文理學(xué)院化工與食品學(xué)院，襄陽 433500)
摘 要: 基于恒應(yīng)變的C型環(huán)測試裝置，采用電化學(xué)噪聲(ECN)研究恒應(yīng)變條件下AA7075高強鋁合金在3%NaCl (質(zhì)量分數(shù))溶液中裂紋的萌生及發(fā)展過程。結(jié)果表明：伴隨著裂紋的萌生和發(fā)展，出現(xiàn)明顯的周期性電流與電位噪聲峰，且這些噪聲峰的出現(xiàn)頻率和時間與3D顯微鏡所觀測到的C型環(huán)試樣表面裂紋的萌生與長大具有良好的一致性；裂紋的萌生與成長并不是連續(xù)發(fā)生的，而是表現(xiàn)出明顯的階段性；恒應(yīng)變試驗后期，隨著C型環(huán)的應(yīng)力松弛，裂紋的縱深延展幾乎停止，但仍然可以捕捉到密集的短時電流噪聲峰，這些噪聲峰可能與裂紋側(cè)壁的亞穩(wěn)態(tài)點蝕生長過程有關(guān)。
關(guān)鍵字: 7075-T6鋁合金；應(yīng)力腐蝕開裂；裂紋萌生；電化學(xué)噪聲
（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
