基于计算流体力学的搅拌摩擦焊数值模拟

摘要

Friction Stir Welding( FSW)is a complex process influenced by many factors,such as tempera-ture,metal flow and microstructure transformation. Temperature and material flow are the main components of the FSW process,which are highly nonlinear and complex. In this study,a finite element model was estab-lished based on the computational fluid dynamics( CFD). The temperature distribution diagram,the velocity vector diagram and the materials streamline distribution diagram at different processing parameters were ob-tained in the FSW process. The results show that the material flow near the pin is more violent with the in-crease of the rotating speed of the pin and the effect of welding speed on material flow is not obvious. It is indicated from the simulation results that material separates in the front of the pin and welds behind the pin. Both the separating and welding occur on the advancing side. The difficulty of welding in FSW increases with the increase of distance from the welding surface,and the unlocked void is more likely to be formed.%搅拌摩擦焊接FSW（ Friction Stir Welding）过程是一个受多参数影响的，温度变化、金属流动和组织转变等多因素互相作用的复杂过程。温度场、流场是FSW过程的主要组成部分，存在高度非线性的复杂耦合作用。基于计算流体力学CFD（ Computational Fluid Dynamics）理论，模拟得到了FSW过程中温度场分布云图、不同工艺参数下的三维速度矢量图和材料流线分布图。结果表明，随着搅拌针旋转速度的增加，搅拌针附近区域材料流动更剧烈，焊接速度的提高对搅拌针及其附近区域材料的流动影响不大。FSW过程中，材料在搅拌针前方分流，在搅拌针后方焊合。分流与焊合位置均位于前进侧。随着距焊缝表面距离的提高，焊合难度增大，从而使FSW过程中未焊合缺陷产生的倾向性增大。