(1. 常州大学 材料科学与工程学院，常州 213164；
2. 常州大学 江苏省材料表面科学与技术重点实验室，常州 213164)
摘 要: 采用慢应变拉伸试验、扫描电镜(SEM)观察以及电化学阻抗谱分析，研究峰时效(PA)、双峰时效(DPA)、回归再时效(RRA)状态下的7003铝合金在3.5%NaCl(质量分数)溶液中应力腐蚀裂纹扩展的特点。结果表明：应力腐蚀裂纹的过程分为两个阶段，即一次裂纹阶段与二次裂纹阶段，其中二次裂纹扩展阶段决定材料的应力腐蚀敏感性。裂纹扩展截面图及阻抗谱拟合结果显示：二次裂纹扩展速率vPA＞vDPA＞vRRA。断口形貌表明：峰时效状态二次裂纹沿晶倾向最为严重，双峰时效次之，回归再时效最轻微。结合应力-应变曲线分析：3种时效状态下的应力腐蚀敏感性为ISCC(PA)＞ISCC(DPA)＞ISCC(RRA)。
关键字: 7003铝合金；电化学阻抗谱；应力腐蚀裂纹；一次裂纹；二次裂纹
（1. School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China;
2. Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164, China）
Abstract:The slow strain rate test (SSRT), scanning electron microscopy (SEM) observation and electrochemical impedance spectroscopy(EIS) analysis were applied to study the stress corrosion cracks propagation of 7003 aluminum alloy under peak aging (PA), double peak aging (DPA) and regression reaging (RRA) in aqueous solution of 3.5% NaCl (mass fraction). The results indicate that the stress corrosion cracks propagation consists of two stages, i.e., initial crack propagation and secondary crack growth, and the secondary crack growth stage decides the stress corrosion cracking (SCC) susceptibility. The secondary crack growth rate of 7003 aluminum alloy under various aging states is as follows, vPA>vDPA>vRRA. The highest intergranular fracture tendency under PA is found by the observation of fracture morphology, DPA take the second place, RRA is the slightest. Cooperated with the stress-strain curve analysis ultimately, the SCC trend under various aging treatment in descending order as follows, ISCC(PA)>ISCC(DPA)>ISCC(RRA).
Key words: 7003 aluminum alloy; electrochemical impedance spectroscopy; stress corrosion cracks; initial crack; secondary crack
