Numerical simulation of friction stir butt-welding of 6061 aluminum alloy

6061铝合金搅拌摩擦对接焊的数值模拟（英文）

A two-dimensional computational fluid dynamics model was established to simulate the friction stir butt-welding of 6061 aluminum alloy. The dynamic mesh method was applied in this model to make the tool move forward and rotate in a manner similar to a real tool, and the calculated volumetric source of energy was loaded to establish a similar thermal environment to that used in the experiment. Besides, a small piece of zinc stock was embedded into the workpiece as a trace element. Temperature fields and vector plots were determined using a finite volume method, which was indirectly verified by traditional metallography. The simulation result indicated that the temperature distribution was asymmetric but had a similar tendency on the two sides of the welding line. The maximum temperature on the advancing side was approximately 10 K higher than that on the retreating side. Furthermore, the precise process of material flow behavior in combination with streamtraces was demonstrated by contour maps of the phases. Under the shearing force and forward extrusion pressure, material located in front of the tool tended to move along the tangent direction of the rotating tool. Notably, three whirlpools formed under a special pressure environment around the tool, resulting in a uniform composition distribution.

建立计算流体动力学二维模型模拟6061铝合金的搅拌摩擦对接焊。运用动网格,使模型中的搅拌针能像实验中的搅拌针一样水平移动和绕轴转动,而且体热源能为模型提供一个与实验相似的温度场。另外,将一小块锌嵌入被焊工件中,作为示踪元素研究焊接流动行为。通过数值模拟,得到焊接过程的温度分布和矢量分布图。通过实验的温度监控以及金相分析,间接证明了模拟结果的合理性。模拟结果表明,焊缝两侧的温度分布并不对称,但具有相同的变化趋势,且前进侧的峰值温度比后退侧高约10 K。迹线图和相分布图反映焊接过程的流动性。在搅拌针转动剪切力和前进挤压作用下,搅拌针周围形成3种运动涡流,这些涡流使得搅拌针周围材料搅拌更加剧烈,成分分布更加均匀。