6082铝合金摩擦搅拌焊缝和熔化极惰性气体保护焊缝电化学性能对比

Comparison of Electrochemical Behaviors between FSW and MIG Joints for 6082 Aluminum Alloy

摘要:

基于动电位极化曲线，交流阻抗谱(EIS) 和扫描电子显微镜(SEM)手段 ,在室温0.2M NaHSO3 和 0.6M NaCl的水溶液中，对比研究了铝合金摩擦搅拌焊(FSW)焊缝和熔化极惰性气体保护焊(MIG)焊缝电化学性能。结果表明： FSW 焊缝的腐蚀速率低于MIG焊缝和母材的腐蚀速率；FSW 焊缝的腐蚀电位高于MIG焊缝和母材的腐蚀电位; FSW 焊缝的腐蚀电流密度低于MIG焊缝和母材的腐蚀电流密度；FSW 焊缝的极化电阻高于MIG焊缝和母材的极化电阻。所有样品的EIS Nyquist 谱图上均有一感抗弧存在；SEM观察表明：仅有少量浅蚀坑出现在FSW焊缝表面。

Abstract:

Electrochemical corrosion behaviors of friction stir welding (FSW) and MIG(mixed inert gas) welding joints of 6082 Al alloy and parent material 6082 Al alloy were investigated in a solution of 0.2M NaHSO3 and 0.6M NaCl ,by using potentiodynamic polarization curve and electrochemical impedance spectroscopy(EIS) and scanning electron microscopy (SEM) observation. The corrosion rate of the FSW joint was less than those of MIG joint and the parent material; the corrosion potential of the FSW joint was more positive than those of MIG joint and the parent material, the corrosion current density of the FSW joint was less than those of MIG joint and the parent material, the polarization resistance of the FSW joint was bigger than those of MIG joint and the parent material. EIS Nyquist loops indicated that an inductive arc existed on the complex plane.SEM observation showed that a few shallow pits presented on the surface of the FSW joint, however, a large number of deeper pits emerged on the surface of the parent materials and MIG joint.