回填式搅拌摩擦点焊热输入对界面孔洞与力学性能的影响

The Impact of Weld Heat Input on Interface Holes and Mechanics Performance during the Process of Refill Friction Stir Spot Welding

目的提高焊接热输入及接头力学性能,研究回填式搅拌摩擦点焊的最佳焊接工艺参数。方法在传统搅拌摩擦点焊产热基础上,结合回填式搅拌摩擦点焊搅拌头具体运动形式,将产热功率对时间进行积分,得到热输入解析方程,测得不同热输入下接头孔洞大小与力学性能,获得热输入对界面孔洞大小与力学性能的影响规律。结果在其他焊接参数不变的条件下,随着转速由2000 r/min提高至2300 r/min,焊接热输入由54 kJ增加至62 kJ,孔洞面积由9.3×104μm2迅速减小至7.7×103μm2,接头拉剪强度由3.2kN提升至7.2 kN。当转速进一步提高至2600 r/min时,热输入达到70.2 kJ时,孔洞的缩减速率与拉剪强度提升速率减缓,孔洞大小减小至3.8×103μm2,拉剪强度减小至8.4 kN。结论在相同的焊接时间下,接头的热输入随着焊接转速的提升而增加,接头孔洞面积减小,拉剪性能提高。

The paper aims to improve the heat input of welding and the mechanical property of joint by studying the optimum welding process parameters of refill friction stir spot welding(RFSSW). On the basis of traditional friction stir spot welding heat production and in combination with the specific motion form of the welding tool, the welding heat production of RFSSW was obtained. And then the heat input of RFSSW is also obtained by integrating the heat production into welding time. The interface hole size and the mechanical properties were measured by under different heat input, and the effect of heat input on the size and mechanical properties of interface voids was obtained. When other welding parameters were kept unchanged, with the increase of rotational speed from 2000 r/min to 2300 r/min, the heat input of welding increased from 54 kJ to 62 kJ, the void area decreased rapidly from 9.3×104 μm2 to 7.7×103 μm2, and the tensile shear strength of joints increased from 3.2 kN to 7.2 kN. When the rotational speed was further increased to 2600 r/min and the heat input reached 70.2 kJ, the shrinkage rate and the increase rate of the tensile shear strength of the holes were slowed down, the size of the holes was eventually reduced to 3.8×103 μm2, and the tensile shear strength is increased to8.4 kN. At the same welding duration, the heat input of the joint increases with the increase of the welding speed. Meanwhile, the joint hole area is reduced, and the shearing performance is improved.