Study on Microstructure and Properties of Refill Friction Stir Spot Welding Joints of 2219 Aluminum Alloy with Different Thickness

ZOU Yangfan, WANG Feifan, LI Wenya, CHU Qiang, TANG Huawei, CUI Fan
2020 Journal of Mechanical Engineering  
摘要:针对航空航天技术需求,采用回填式搅拌摩擦点焊技术对不等厚(2 mm+8 mm)2219 铝合金板进行了焊接。通过改变 焊接工艺参数(旋转速度、焊接时间和下压量),分析了不同焊接参数对点焊接头宏、微观组织及力学性能的影响规律。结果 表明,随着旋转速度的增加,点焊接头拉剪力先增加,后降低;而延长焊接时间,可以提高接头拉剪力,但过长的时间会导 致接头拉剪力降低;焊接下压量的选择,既要保证上下板的结合,又不能导致下板过度软化。当旋转速度为 1 800 r/min,焊 接时间为 6 s,下压量为 2.6 mm 时,所获点焊接头的拉剪力最大,为 7 924 N。回填式搅拌摩擦点焊接头有三种断裂型式: Abstract:According to the requirements of aerospace technology, refill friction stir spot welding technology was used to weld 2219 aluminum alloy plates with different thickness (2 mm+8 mm). By
more » ... 2 mm+8 mm). By changing welding process parameters (rotation speed, welding time and plunge depth), the influences of welding parameters on the microstructure and mechanical properties of welded joints were analyzed. The results show that with the increase of rotation speed, the tensile-shear strength of the joints increases first, and then decreases. The extension of welding time can increase the tensile-shear force of the joint, but too long time will lead to the reduction. The selection of plunge depth should not only ensure the combination of upper and lower plates, but also not lead to excessive softening of lower plates. What's more, when the rotation speed is 1 800 r/min, the welding time is 6 s, and the plunge depth is 2.6 mm, the optimal tensile-shear force of the joint is 7 924 N. There are three fracture modes of refill friction stir spot welded joints: plug fracture, shear fracture and plug-shear fracture. Among them, the tensile-shear force of the spot welded joint is larger when the type of plug-shear fracture occurs. Key words:2219 aluminum alloy;different thickness;refill friction stir spot welding;microstructure;mechanical properties 0 前言 在航空航天铝合金构件制造过程中,经常会遇 * 国家自然科学基金资助项目(51574196,U1637601)。20190829 收到初 稿,20200210 收到修改稿 到不等厚铝合金的连接,传统工艺采用电阻点焊, 但实践表明,电阻点焊的焊点质量不稳定,对工艺 参数的波动十分敏感,经常出现问题,尤其当两个 被连接铝合金构件的壁厚差变大以后,电阻点焊的 可焊性严重降低 [1-4] 。搅拌摩擦点焊(Friction stir spot welding, FSSW)是在传统搅拌摩擦焊(Friction stir
doi:10.3901/jme.2020.06.176 fatcat:a43ufulmqnfqho2xfko5z2rrta