5083铝合金搅拌摩擦焊缝的剥落腐蚀性能

Exfoliation corrosion resistance of 5083 aluminum alloy welds processed by friction stir welding

摘要:

采用溶液浸泡法研究了5083铝合金及其搅拌摩擦焊焊缝的剥落腐蚀性能。借助光学显微镜、扫描电子显微镜、透射电子显微镜及电化学工作站分析了焊缝和母材的微观组织、剥落腐蚀形貌、极化曲线及电化学阻抗谱。结果表明，浸泡腐蚀后焊缝出现轻微点蚀，而母材点蚀严重并显现局部起皮剥落，腐蚀裂纹沿晶开裂；腐蚀评级和电化学阻抗谱均可说明焊缝的耐剥落腐蚀性能好于母材，同时极化曲线也说明焊缝的腐蚀敏感性低于母材。带状晶粒等轴化，棒状的第二相细化及分布均匀化，位错密度的减小是焊缝耐剥落腐蚀性能强于母材的主要原因。

Abstract:

The exfoliation corrosion resistance of the 5083 aluminum alloy and its FSW joints were studied in this paper.The corrosion morphology,microstructure,electrochemical impedance spectroscopy (EIS) and polarization potential of the samples were analyzed by using optical microscope (OM),scanning electron microscope (SEM),transmission electron microscopy(TEM)and electrochemical workstation.The results showed that only slight pitting occurred in the joint.However,the base metal suffered from serious pitting and even peeling.It developed intergranular cracking showed in SEM morphology.The EIS results indicated that the reaction resistance of the joint is larger than that of base metal.The equiaxed microstructure,fine and homogeneous precipitate and low dislocation density resulted in better properties of joints in exfoliation corrosion resistance than that of the base metal.