外加电位条件下7A52铝合金应力腐蚀开裂敏感性研究

Investigation of Stress Corrosion Cracking Susceptibility of 7A52 Aluminum Alloy under Different Applied Potentials

摘要：采用电化学极化手段和慢应变速率拉伸试验，结合扫描电镜观察合金断口形貌，研究了外加电位对7A52铝合金应力腐蚀开裂敏感性的影响。研究结果表明：合金在3．5％NaCl溶液中的应力腐蚀开裂敏感性与外加电位有强烈的相关性，开裂敏感性在外加电位为一0．95V时最低，外加电位起到阴极保护的作用；在外加电位为一1V时有所升高，但仍然低于开路电位条件下的敏感性；在一1．1V时最高，应力腐蚀过程以氢脆为主；在一1．2V时又有所降低，阴极析出的氢以气态逸出而降低应力腐蚀开裂敏感性。

Electrochemical polarization method and slow strain rate test are used to investigate effects on Stress Corrosion Cracking（SCC） susceptibility of 7A52 aluminum alloy under different applied potentials based on the fracture appearance observed by Scanning Electron Microscope （SEM）. The results show there is a correlation between SCC susceptibility and applied potentials of alloy in 3.5% NaC1. Namely, SCC susceptibility is the lowest when applied potential is - 0.95 V and the applied potential plays the role of cathode protection ; it rises when applied potential is - 1 V but lower than that of open circuit potential; it is the highest when applied potential is - 1.1 V, and hydrogen embrittlement is the main strain corrosion process; it declines, however, when applied potential is - 1.2 V and hydrogen separated out from cathode overflows in form of gas and reduces the stress corrosion cracking susceptibility.