(1. 沈阳航空航天大学航空航天工程学部，沈阳 110136；
2. 北京航空航天大学机械工程与自动化学院，北京100191)
摘 要: 以LY12铝合金为研究对象，对常规搅拌头作用下的回填式搅拌摩擦点焊的材料流动规律进行数值模拟，并利用焊点的宏观形貌与显微组织进行试验验证；讨论不同搅拌头形状对材料流动行为的影响。结果表明：材料的高速流动区域主要位于套筒内外壁附近；流动速度值在外壁凹槽处出现最大值，且随着离套筒壁距离的增加而减小。流动规律的模拟结果由位于焊点中心的中间较宽、两端较窄的韧带与焊点内部不同区域晶粒的不同所证实。从减小焊点内韧带宽度的角度考虑，双凹槽搅拌头优于常规搅拌头、小槽宽搅拌头和大直径搅拌头。
关键字: 回填式搅拌摩擦点焊；搅拌头形状；数值模拟；材料流动
（1. Faculty of Aerospace Engineering, Shenyang Aerospace University, Shenyang 110136, China;
2. School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China）
Abstract:Choosing LY12 aluminum alloy as the research object, the material flow behavior of friction spot welding (FSpW) using conventional tool was simulated and verified by macrostructure and microstructure of welding spot. Meanwhile, the effects of tool geometries on material flow behavior during FSpW process were mainly discussed. The results show that the material near the inner and outer walls of sleeve attains high flow velocity. The maximum flow velocity appears in the groove region of the outer wall. And the velocity decreases as the distance from the walls of the sleeve becomes bigger. Bonding ligament with bigger width in the center and smaller width in two ends and different microstructures in different regions agree with the simulation results. From the viewpoint of decreasing the width of the bonding ligament, the double groove tool is better than the conventional tool, small width groove tool and big diameter tool.
Key words: refill friction stir spot welding; tool geometry; numerical simulation; material flow
