铝锂合金搅拌摩擦搭接焊接头组织与性能研究

Study on Microstructure and Properties of Friction Stir Welding Aluminum-Lithium Alloy in Lapped Joints

摘要: 以厚度为1.5mm的5A90铝锂合金为研究对象，开展了铝锂合金搅拌摩擦搭接焊工艺研究，分析不同焊接速度对搭接接头组织及硬度的影响。结果表明：当转速为1200 r/min，焊接速度为100 mm/min时，焊接接头组织致密，焊核区为细小均匀的等轴晶粒；热机影响区出现弯曲或拉伸变形，热影响区晶粒尺寸发生粗化。搭接接头母材区的硬度最高，在热机影响区和热影响区硬度下降，在焊核区硬度上升。在焊核区与热机影响区的交界处硬度会发生突变现象。

Abstract: The friction stir lap welding process for 1.5 mm 5A90 aluminum-lithium alloy was researched. The effect of welding speed on microstructure and hardness of lap joint was analyzed. The results show that when the rotational speed is 1200 r/min and the welding speed is 100 mm/min, the microstructure of the joint is compact, and the weld nugget zone is a fine uniform equiaxed grain; The grain bending or elongation occurs in the thermal-mechanically affected zone, and the grain size of the heat affected zone is coarsening. The hardness of the base metal zone is the highest, and decreases in the thermal-mechanically affected zone and heat affected zone, and increases in the nugget zone. The hardness at the junction of the nugget zone and the thermal-mechanically affected zone will mutate.