搅拌针形状对焊缝厚度方向塑性金属迁移的影响

采用铝箔作为标示材料,用不同旋向、不同螺距的搅拌针进行了搅拌摩擦焊试验.结果表明,搅拌针的旋向决定塑性金属在厚度方向上的迁移方向,带左旋螺纹的搅拌针驱使搅拌针附近的塑化金属向下迁移,向下迁移的金属不断向焊缝底部积累并受到垫板的阻碍作用,迫使塑性金属挤压外围的材料向上迁移,右旋螺纹的搅拌针作用方式则相反;建立的"抽吸-挤压"模型能很好的解释塑性金属在焊缝厚度方向上的迁移方式;螺距较大的搅拌针有利于塑性金属在焊缝厚度方向上的迁移,但也容易使焊缝底部的包铝层卷入焊缝中.

Effects of Pin Shape on Transfer of Plastic Metal in Weld Thickness Direction

Taking aluminum foils as a tracer material, friction stir welding was conducted by using different thread direction and different pitched pin. The results show that thread direction decides the transfer direction of plastic material in weld thickness direction, left hand thread pin drives the plastic metal around the pin to move downwards, plastic metal accumulates at the bottom of the weld and is blocked by the backing plate, then begins to force its peripheral metal around the pin tip to move around and upwards, however the right hand thread pin has contrary influence on transfer of plastic metal. The established physical model for suction-extrusion of plastic metal can give sound explanation for transfer behavior of plastic metal in the weld thickness, it is good for plastic metal to transfer in the weld thickness direction by using thread pin with big pitch, but it is also easy to curl the aluminum layer on the back of the based material into the weld, which will affect the quality of the weld.