Sep 03, 2020
The High-power Fiber Laser Technology Laboratory of Shanghai Institute of Optics and Fine Mechanics （Chinese Academy of Sciences） has made new progress in the elimination of pores in automotive aluminum alloy lap laser welding. A new method for eliminating pores in aluminum alloy laser welding is proposed and the mechanism of pore elimination is revealed. Traditional laser welding is mainly carried out in a single mode: heat conduction welding mode or keyhole deep penetration welding mode. The new laser welding method realizes laser welding through mixed modes: keyhole deep penetration welding mode + heat conduction welding mode.
Aluminum alloys are widely used in industries such as automobiles, aerospace, and rail transit. The traditional connection methods are mainly realized through mechanical connection and arc welding. Conventional laser welding aluminum alloys can easily cause keyholes to collapse and form pores due to the existence of oxide films on the surface of aluminum alloys and the low surface tension of liquid aluminum alloys. There are a large number of pores in the weld, which reduces the effective joint area between overlapping workpieces, makes the mechanical properties of the joint weak, and limits the application of laser welding technology to aluminum alloys.
The research team proposed a new method combining the ultra-high scanning speed (43.5m/min) different from the conventional welding process (3.0m/min) and the path of the oscillating laser beam, and proved the amplitude of oscillating and the number of pores in the weld. the relationship between. The results show that the new method can effectively eliminate pores. When the swing amplitude is greater than the focal diameter of the laser beam, almost no porosity can be produced, and the tensile and shear strength of the joint can be increased by more than 75%.
The swing amplitude increases successively, and the pores gradually decrease.
[Tanslation of an article from weibo.com/中科院之声；
Refer to the paper:https://www.sciencedirect.com/science/article/abs/pii/S0924013620302405#!]