6061铝合金厚板搅拌摩擦焊接头组织与耐蚀性

采用搅拌摩擦焊对30 mm厚的6061铝合金进行了双面对接焊，分别采用金相显微镜、显微硬度仪和电化学工作站对焊接接头的组织、硬度和耐蚀性能进行观察、测量和研究。金相观察显示，双面搅拌摩擦焊焊缝前进侧与母材有明显的分界，后退侧分界模糊；焊核区呈均匀细小的等轴晶。硬度测试表明，搅拌摩擦焊接接头硬度呈“W”形特征分布，硬度最低值出现在前进侧热影响区。腐蚀试验表明，双面焊焊核重叠区腐蚀电流(2.396 3×10-5A/cm2)较大，一旦开始腐蚀，腐蚀速度很快，耐腐蚀能力相对较差。

Microstructure and corrosion resistance of friction stir welded joints of thick 6061 aluminum alloy plate

The double-sided friction stir welding process were used to weld 6061 aluminum alloy with the thickness of 30 mm, and the microstructure, micro-hardness and corrosion resistance of the welded joints were analyzed and tested by means of metallographic microscope, micro-hardness tester and electrochemical workstation. The metallographic observation shows that there is an obvious boundary between the advancing side of the friction stir welded joint and the base metal, while the boundary of retreating side and the base metal is blurred, the grains in weld nugget zone are homogeneous and fine equiaxed crystal. The micro-hardness curve of friction stir welded joints shows a “W” shape. The minimum micro-hardness appears in the heat affected zone. The corrosion test shows that the corrosion current is larger in the overlapping area of double-side welded joints, once the corrosion is started, the corrosion speed is very fast, and the corrosion resistance is relatively poor.