Stress corrosion behavior of 6082 aluminum alloy
Stress corrosion behavior of 6082 aluminum alloy
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DOI：
10.1002/maco.201911433
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发表时间：
2020-01
期刊：
影响因子：
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通讯作者：
Biner Zhou;Li Yang;Shou‐bing Yang;D. Bai;O. Olugbade;Gen‐zhe Huang
中科院分区：
文献类型：
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作者：
Biner Zhou;Li Yang;Shou‐bing Yang;D. Bai;O. Olugbade;Gen‐zhe Huang
采用三点弯曲夹具，在保持50%屈服强度状态下，在1.5% NaCl电解液中浸泡不同时间，对6082铝合金进行应力腐蚀试验。测量电化学阻抗谱和动电位极化曲线来表征合金的应力腐蚀行为。光学显微镜、扫描电子显微镜和 X 射线能谱分析用于微观结构研究。结果表明，所有奈奎斯特电化学阻抗谱均由高频和低频双电容弧组成。然而，在保持50%屈服应力的情况下，增加浸泡时间会导致腐蚀电流密度相应增加，导致腐蚀深度逐渐增长，合金的耐腐蚀性能下降。 6082铝合金含有AlMnFeSi、Mg2Si和Si第二相。不同的第二相表现出不同的应力腐蚀行为。应力腐蚀裂纹产生于AlMnFeSi与基体的边界处或AlMnFeSi相内部。裂纹方向始终垂直于所施加的拉应力。 Mg2Si第二相由于其腐蚀电位低于基体而发生自腐蚀。由于Si的电位高于基体的电位，腐蚀发生在Si与基体边界的基体侧。
Stress corrosion tests of 6082 aluminum alloy were carried out by using a three‐point bending fixture while holding at 50% of yield strength state through different immersion times in 1.5% NaCl electrolyte solution. The electrochemical impedance spectra and dynamic electric potential polarization curves were measured to indicate the stress corrosion behavior of the alloy. Optical microscopy, scanning electron microscopy, and X‐ray energy spectrum analysis were applied for microstructural investigations. The results show that all of the Nyquist electrochemical impedance spectra consisted of high‐ and low‐frequency double capacitive arcs. However, an increase in immersion time while holding at 50% of yield stress resulted in a corresponding increase in the corrosion current density, leading to gradual corrosion depth growth, and a decrease in the corrosion resistance of the alloy. 6082 Aluminum alloy included AlMnFeSi, Mg2Si, and Si secondary phases. The different secondary phases presented different stress corrosion behaviors. Stress corrosion cracks were generated at the boundaries of AlMnFeSi and matrix or within the AlMnFeSi phase. Crack direction is always perpendicular to the tensile stress applied. Mg2Si secondary phase was self‐corroded as its corrosion potential is lower than that of the matrix. As the electric potential of Si is higher than that of the matrix, corrosion occurred at the matrix side of the boundary between Si and matrix.