6005A铝合金焊接接头的腐蚀行为

Corrosion Behavior of Aluminum Alloy 6005A Welding Joint

采用浸泡试验和电化学方法研究了6005A铝合金焊接接头在不同介质环境中的腐蚀行为,采用光学显微镜、扫描电子显微镜、电子能谱分析了焊缝微观组织和成分的变化.结果表明,由于ER5356焊丝Mg含量较高,致使焊缝中Mg含量高于母材,因此焊缝耐蚀性能低于母材;在浸泡试验中焊缝发生均匀腐蚀,表面呈多孔形貌,其对光线的反射明显弱于仅发生点蚀的母材,表现出焊缝发黑的现象;焊接接头在0.1 M NaCl、0.1 M Na2SO4和0.1 M NaNO3溶液中的腐蚀速度为VNaCl>VNaSO>VNaNO.

Immersion test and electrochemical methods were used to study the corrosion behavior of a 6005 A aluminum alloy welding joints in different environment, the change in microstructures and compositions of the welding joints were analyzed by optical microscopy, scanning electron microscopy, electron dispersive X-ray spectroscopy. The results show that the high Mg content in the weld originated from the welding wire ER5356 is the main reason of lower corrosion resistance in the weld compared with the base metal. Uniform corrosion of the weld takes place during the immersion test and forms porous surface that reflects less light than that on the base metal in which only pitting corrosion oceurrs. The corrosion rate of the welding joint in the aqueous solutions is VNaCl〉 Va2SO4〉 VNaNO3.