超声空化处理对冷金属过渡焊接过程的影响

Effect of Ultrasonic Cavitation Treatment on Cold Metal Transfer Welding Process

为了解决6061铝合金冷金属过渡(CMT)焊接过程中,因其表面的一层致密氧化膜而在焊接时产生焊渣与气孔缺陷的问题,课题组对此进行了研究,发现超声空化处理后的6061铝合金表面氧化膜厚度明显减小,可显著改善CMT焊接熔池的流动过程,减少焊渣缺陷。同时,超声空化处理可以减少熔池中的氧化膜颗粒,促进孔隙非均质形核向均质形核转变,减缓孔隙形核速率,降低孔隙形成直径。此外,寻求最佳的脉冲电流,控制熔池的温度梯度分布,减小熔池内部的洛伦兹力和熔池表面张力梯度引起的剪应力,可以获得更好的焊缝连接。实验结果表明:超声空化处理焊缝组织性能达到最佳时,脉冲电流较大,极限抗拉强度从158.7 MPa提高到208.7 MPa,组织性能明显优于普通焊缝。

In order to solve the welding slag and pore defects during the cold metal transfer(CMT) welding process caused by the dense oxide film on the surface of ordinary 6061 aluminum alloy, the research was carried out. It was found that the 6061 aluminum alloy treated by ultrasonic cavitation had a significantly smaller surface oxide film thickness, which can significantly improve the flow process of the molten pool of CMT welding and reduce welding slag defect. At the same time, the ultrasonic cavitation treatment can reduce the oxide film particles in the molten pool, promote the conversion of pore heterogeneous nucleation to homogeneous nucleation, slow down the pore nucleation rate, and reduce the diameter of pore formation. In addition, a better weld connection can be achieved by seeking the best pulse current, controlling the temperature gradient distribution of the molten pool, reducing the Lorentz force inside the molten pool and the shear stress caused by the surface tension gradient of the molten pool. The experimental results show that the pulse current is larger when the weld structure performance of the ultrasonic cavitation treatment reaches the best, and the ultimate tensile strength is increased from 158.7 MPa to 208.7 MPa, and the structure performance is significantly better than that of ordinary weld.