铝合金搅拌摩擦点焊接头塑化金属流动形态分析

在搅拌摩擦点焊过程中，塑化金属的流动形态是影响焊点成形及接头力学性能的主要因素。通过采用镶嵌标识材料的方法，研究了搅拌摩擦点焊过程中接头塑化金属的流动形态。结果表明，在焊点横截面上，匙孔两侧塑化金属发生塑性变形的宽度基本相同，从焊点表面到底面，塑性变形区宽度逐渐减小。在焊点的上部，塑化金属主要受轴肩的作用，在轴肩摩擦力和材料之间的剪切力作用下沿搅拌针旋转的方向运动，随着距焊点表面距离的增大，塑化金属沿搅拌针旋转方向的运动趋势逐渐减小。搅拌针周围的塑化金属在搅拌针螺纹向下的压力作用下，以螺旋状向焊点底部运动，运动到焊点底部后受底板的阻碍和未塑化金属的挤压作用从搅拌针四周向焊点上部运动。

Analysis of plastic material flow behavior during friction stir spot welding for aluminum alloy

Plastic material flow is an important factor influenceing the surface shaping and mechanical property of joint during the friction stir spot welding process.In this paper, the plastic material flow behavior was investigated by lamella plates made up with thin copper foils and aluminum plates.The results show that, in the cross section of the joint, the plastic material in the both sides of the keyhole was equal wide in general.From top to bottom, the width of deformation decreased gradually.The plastic material at the top of joint was mainly influenced by the tool shoulder.Under the driving friction force of the shoulder and the shear between the shoulder and material, plasticmaterial flowed around the rotating pin, the trend of flow decreased with the increasing of distance to the shoulder.Under the action of screwed pin, the plastic material moved in a spiral flow around the rotating pin.When the plastic material flowed to the bottom of joint, the plasticmaterial moved upwards and outwards around the pin under the block of the backplane at the bottom and the extrusion force of un-plastic material, then plastic material that arrived the top moved to the bottom under the effect of shoulder, thus formed a cycle.