搅拌针偏移量影响铝镁异质金属搅拌摩擦焊材料流动的数值模拟
Numerical Simulation Study of the Influence of the Offset of the Stirring Pin on the Material Flow in Friction Stir Welding of Aluminum and Magnesium Dissimilar Alloy

本文采用耦合的欧拉–拉格朗日方法，构建了添加中间金属的铝镁异质合金搅拌摩擦焊的数值分析模型。针对两种不同配置进行了研究：一种是搅拌头轴线与焊缝中心线重合(配置1)，另一种是搅拌头轴线向铝合金偏置1 mm (配置2)。研究结果显示，配置1的材料流动更为充分。在前进侧，铝合金主要从搅拌头前方水平流动至后退侧；而在后退侧，一部分镁合金从搅拌头后方水平流动至前进侧，另一部分则从搅拌头后方向板厚底部流动，随后在螺纹搅拌针的作用下继续向板厚上方流动。根据材料流动范围，可将接头横截面划分为轴肩影响区和搅拌针影响区。中间金属的流动分为3个区域。配置2在轴肩影响区和搅拌针影响区的铝/镁截面都更为光滑和规则。由于材料流动的不充分，所以配置2在接头内部形成了“隧道”缺陷。
This article uses the coupled Euler-Lagrange method to establish a numerical analysis model of friction stir welding of Aluminum and Magnesium dissimilar alloy with intermediate metal. Two different configurations are studied: one in which the axis of the stirrer is aligned with the centerline of the weld (configuration 1), and the other in which the axis of the stirrer is offset by 1mm towards the aluminum side (configuration 2). The results show that material flow is more complete in configuration 1. On the advancing side, aluminum mainly flows horizontally from the front of the stirrer to the retreating side. On the retreating side, some magnesium flows horizontally to the advancing side, while another part flows from the back of the stirrer towards the bottom of the plate thickness and then continues to flow towards the top of the plate thickness under the action of the threaded stirring needle. According to the range of material flow, the cross-section of the joint can be divided into two areas: the shoulder influence zone and the needle influence zone. The flow of intermediate metal is divided into three regions. In configuration 2, both the aluminum/magnesium cross-sections in the shoulder and needle influence zones are smoother and more regular. However, due to insufficient material flow, configuration 2 forms a “tunnel” defect inside the joint.