新型可焊6005A铝合金的腐蚀行为

采用电化学交流阻抗谱,极化曲线以及浸泡腐蚀实验研究了Cu含量变化对高速列车用6005A铝合金电化学腐蚀行为的影响.结果表明:在商用6005A铝合金基体中添加适量的Cu元素,可有效提高氧化膜的致密性.当添加Cu质量分数为0.4%时,轧制态6005A铝合金电化学交流阻抗图谱中腐蚀反应电阻Rct值较大,双电层电容Q2值较小,极化曲线出现了较宽电位范围的阳极钝化区.但合金自腐蚀电流小幅增加,显示合金局部耐蚀性下降.在质量分数为3.5%NaCl溶液中进行的浸泡实验显示,随着浸泡时间的延长,自制6005A铝合金依次发生点蚀、晶间腐蚀和剥蚀.合金表面氧化膜致密性是影响材料抗腐蚀能力的主要因素.

Corrosion Behavior of a New Weldable Aluminum Alloy: 6005A

The effect of Cu content in the 6005A aluminum alloy used for high-speed trains on its electrochemical behavior was investigated by electrochemical impedance spectroscopy(EIS), immersion test and polarization curves. The results showed that a proper Cu content can improve efficiently the compactness of the alloy's surface oxide films. When the Cu content is 0.4%, the reactive resistance Rct due to corrosion as shown on the electrochemical impedance spectroscopy of 6005A increases and the double-layer capacitance Q2 decreases, and the polarization curve exhibits an anode passivation zone in a wide range of potential. However, the alloy's self-corrosion density increases slightly, which means that the corrosion resistance of the alloy decreases. Moreover, the immersion test for the alloy immersed in the 3.5% NaCl solution revealed that the pitting corrosion, intergranular corrosion and exfoliation corrosion occur sequentially on the alloy. The main influence factor on the corrosion resistance of the alloy is the compactness of its surface oxide film.