对AZ31B镁合金板进行了搅拌摩擦焊, 研究了焊接接头的显微组织、物相组成、硬度及耐腐蚀性能。结果表明: 该接头焊核区为细小均匀的等轴晶, 热机械影响区晶粒得到细化但沿金属塑性流动方向被拉长, 热影响区的显微组织与母材区的比较接近, 但其晶粒略粗大; 与接头母材区相比, 焊缝的物相组成未发生变化, 各区的硬度有所降低且硬度随距焊缝中心距离的增加呈先减小后增大的变化趋势, 硬度最低处位于热机械影响区内; 接头的耐腐蚀性能略低于母材的, 浸泡腐蚀后接头表面发生全面腐蚀, 但各区域的腐蚀程度并不相同, 热机械影响区的腐蚀最严重。

The AZ31B magnesium alloy sheets were welded by friction stir welding and the microstructure, phase composition, hardness and corrosion resistance of the welded joints were investigated. The results show that the weld nugget zone of the joint was composed of small equiaxed grains and the grains in the thermal-mechanical affected zone were refined and elongated along metal plastic flow direction. The microstructure of the heat affected zone was close to that of the base metal but the grain size was slightly larger. Comparing to the base metal of the welded joint, the phase composition of the weld seam had no change but the hardness decreased slightly. The hardness in different zones first decreased then increased with the increase of the distance from the weld seam center and the lowerest hardness appeared in the thermal-mechanical affected zone. The corrosion resistance of the joint was slightly lower than that of the base metal. The surface of the joint was general corroded after immersion corrosion. However, the corrosion degrees of the different zones of the joint were different. The corrosion of the thermal-mechanical affected zone was the most serious.