超声能对铝合金搅拌摩擦焊焊缝成型的影响

为了探究超声能对铝合金搅拌摩擦焊（FSW）焊缝成型及焊缝缺陷的影响机理，采用数值模拟和试验验证相结合的方法，设计了同等工艺条件下的超声辅助搅拌摩擦焊（UAFSW）与搅拌摩擦焊的流场仿真和试验对比。通过分析2种焊缝横截面上热塑性金属的流动矢量和金相组织，研究了超声能导入后焊缝热塑性金属的流动变化情况。分析结果表明:超声能导入，使铝合金搅拌摩擦焊焊缝内金属的水平绕流方式演变成倾斜绕流方式，并使上下2个独立流场实现交汇统一，而且使焊缝金属最低流速提升近一个数量级，焊缝成型完整度明显增强，焊缝缺陷率大幅降低。 

Influence of ultrasonic energy on weld formation of friction stir welding of aluminum alloy

In order to find out the influence mechanism of ultrasonic energy on the weld formation and weld defects of aluminum alloy Friction Stir Welding (FSW), the combined method of numerical simulation and experimental verification was used to design the comparison of the flow field simulation and test between Ultrasonic Assisted Friction Stir Welding (UAFSW) and friction stir welding under the same process conditions. The flow vector and metallographic structure of the thermoplastic metal on the cross section of the two types of weld are analyzed to find out the flow changes of the weld metal after ultrasonic introduction. The analysis results show that the introduction of ultrasonic energy makes the horizontal flow pattern of the metal in the friction stir welding of aluminum alloy evolve into a sloping flow mode, the two upper and lower independent flow fields are unified, and the lowest flow rate of the weld metal has up to one order of magnitude improvement. The integrity of weld formation is significantly enhanced, and the weld defect rate is greatly reduced.