AA7075铝合金应力腐蚀开裂过程中裂纹萌生和发展的电化学噪声：Electrochemical noise in the initiation and development of crack initiation and development of AA7075 aluminum alloy during stress corrosion cracking.pdf

第25卷第12期 Volume 25Number 中国有色金属学报 The Chinese Journal of Nonferrous Metals 2015年12月 December 2015 文章编号:1004-0609(2015)12—3282—1 AA7075铝合金应力腐蚀开裂过程中裂纹萌生和发展的电化学噪声李文婷1,潘若生2,赵苇杭1,董泽华1,3 (,武汉430074; ,松原131200; ,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%NaCI (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。关键词:;应力腐蚀开裂;裂纹萌生;电化学噪声中图分类号:TGl72 文献标志码:A Electrochemical noise ofcrack initiation and propagation of AA7075 aluminium alloyduring stress corrosion cracking ,PAN Ruo—shen92,ZHAO ,DONG ,3 ( ofChemistry and Chemical Engineering,Huazhong University ofScience andTechnology, Wuhan 430074,China; Technology Research InstituteofJilinOilfieldofPetroChina,Songyuan 3200,China; ofChemical andFood Sciences,Hubei InstituteofArts,Xiangyang 433500,China) Abstract:The initiationandpropagation process of stress corrosion cracking ofAA7075 high strength aluminium alloy were investigated by electrochemical noise in3%NaCI(mass fraction)solution by a constant strain test resultsshow thatthepropagation ofcracks can produce theintensive andregular potential and current noise addition,the beginning time andfrequency ofnoisepeaks are consistent with theinitiationand growth process ofcracks viaonline 3D microscope theshape and lifespan analysis ofnoise peaks,the advance ofcracks an intermittent process deepening process ofcrack almost inhibited due totherelaxation of stress on the C—,the dense short-time noise peaks can be observed,which possibly induced by the metastable pit corrosion along thecrack mouth. Key words:7075-T6 aluminium alloy;stress corrosion cracking;crack initiation;electrochemical noise AA7075是Al—Zn—Mg-Cu系高强铝合金,具有比强度高、密度低和弹性模