Defects Analysis And Improvement For Laser Welding Of Aluminum Alloy With Filler Wire

Laser welding with filler wire is commonly used in the welding technology of aluminum alloy. Filler wire can reduce the accuracy requirement of the parent metal assembly. At the same time by adding the required alloying elements, it can improve the organization and performance of the weld. Due to the impact of the welding wire on the weld pool and the keyhole, it will make the weld easy to appear on the surface of molding bad and porosity and other defects.For this reason, this article will through the high-speed camera system and X-ray transmission system, to research the defects of the surface and porosity of the weld. According to the nature of the porosity occurrence reason, this article put forward the improvement measures of laser welding filler wire.Firstly, the process and influence factors of weld surface defects are studied. Through the early experiments, wire position and parent metal surface had a greater influence on the forming of weld surface. When the light wire spacing DL-W is-2mm, in the heating effect of the laser welding wire was large droplets transition, the weld surface discontinuity defects. When the light silk offset dl-w is1.2mm, asymmetric defects will occur on the surface of weld. When the gap of base metal is increasing gradually, it will increase the amount of stay on the back of weld. When the clearance between the parent metal is not uniform, the weld surface will appear uneven, staying and weld leakage defects.Secondly, the movement of bubbles in the molten pool and influencing factors are studied. In laser welding, when the welding speed is low, bubbles moving along melt the bottom edge to the rear; when the welding speed is high, the bubble moves upward along the keyhole rear wall. Filler wire will affect the stability of the molten pool and keyhole, to increase the number of pores in weld. The liquids in the molten pool spiral upward mobility when the welding speed is low, keyhole molten pool of liquid along the back wall directly upward mobility. The movement of bubbles in the molten pool rule and the liquid flow pattern of molten pool have a strong relationship. The flow of the molten pool is a driving force of the motion of bubble.Finally, put forward the improvement measures of laser welding with filler wire. Through the above mentioned analyzing, the essential reason of the weld porosity populations after wire filling welding wire is the impact on the keyhole. It can hinder the bubbles of the keyhole overflow. For this reason, this article presents arc melt in advance of laser welding with filler wire and double-focus melting in advance of laser welding with filler wire. In the arc melt in advance of laser welding with filler wire, wire is melted in advance by the TIG arc. It can reduce the impact of wire on the keyhole, and reduce the porosity in the weld significantly. In the double-focus melt in advance of laser welding with filler wire, it can increase the distance between the keyhole and wire solid end, reduce the impact of wire on the molten pool and keyhole, and reduce the porosity in the weld.