搅拌针锥度和螺纹头数对厚板铝合金FSW焊缝金属迁移的影响

研究了20 mm厚2024-T4铝合金板材在搅拌摩擦焊过程中，搅拌针锥度与搅拌针表面螺纹头数对焊缝塑性金属在搅拌针周围迁移程度的影响.结果表明，随搅拌针螺纹头数增加，搅拌头旋转1圈时搅拌针螺纹所转移的高温金属量增加，焊核中塑性金属在前进边和返回边的轴向上迁移程度增加，宏观表现为焊核高度、宽度和面积增大；搅拌针锥度由25°减少至15°时，焊缝塑化金属量增加，焊核塑性金属在焊缝横截面上横向和轴向的迁移程度都增大，焊核面积增大.采用多头螺纹和较小锥度的搅拌针，可以改善厚板焊接时温度梯度大、焊缝金属流动不充分的问题，保证焊缝冶金质量.

Effects of taper and thread number of stir pin on weld metal migration in FSW of thick aluminum

The effects of the taper and the thread number of the stir pin on the plastic metal transfer in the weld transverse section during friction stir welding process were investigated by using aluminum alloy 2024-T4 with the thickness of 20mm. The results show that, the volume of the high temperature metal migrated with the thread of the stirring pin increases with the increase of the thread number on the stir pin when the stir tool is rotated one round. The transfer extents of the plasticized metal in the nugget at the advancing side and retreating side increase in weld thickness direction. That is to say, the height, width and transverse section area of the weld nugget increase in the macroscopic view. When the taper of the stir pin is decreased from 25°to 15°, the amount of the plasticized metal in weld increase, and the transfer extents of plasticized metal on transverse and axial direction increase, and the area of weld nugget also increases. Therefore, when a stir pin with multiple threads or smaller taper is used, the problems of the large temperature gradient at the direction of the plate thickness and the insufficient metal migration in the weld for thick plate FSW can be overcome and the metallurgical quality of the weld can be guaranteed.