Abstract
The effects of arc modes on laser-arc hybrid welding for AA6082-T6 aluminum alloy were comparatively studied. Two arc modes were employed: pulsed metal inert gas arc and cold metal transfer arc. The results indicated that joints without porosity, undercutting, or other defects were obtained with both laser-pulsed metal inert gas hybrid welding (LPMHW) and laser-cold metal transfer hybrid welding (LCHW). Spatter was reduced, and even disappeared, during the LCHW process. The sizes of equiaxed dendrites and the width of the partially melted zone in the LPMHW joint were larger than those in the LCHW joint. The microhardness in each zone of the LPMHW joint was lower than that of the LCHW joint. The softening region in the heat-affected zone of the LPMHW joint was wider than that of the LCHW joint. The tensile strength of the LCHW joint was higher than that of the LPMHW joint. For the two joints, the fractures all occurred in the softening region in the heat-affected zone, and the fracture morphologies showed ductile fracture features. The dimples in the fractograph of the LCHW joint were deeper than those of the LPMHW joint.
Highlights
The application of lightweight materials is one of the most strategic approaches to increase the operational speed of delivery vehicles
Aluminum alloys are joined by arc welding, especially metal inert gas (MIG) welding
Considering the physical-chemical characteristics of aluminum alloys, numerous results indicate that some obvious drawbacks such as: large welding deformation, serious joint softening, and low production efficiency would appear during the arc welding process due to the high heat input and low welding speed [3,4,5]
Summary
The application of lightweight materials is one of the most strategic approaches to increase the operational speed of delivery vehicles. In the high-speed train manufacturing industry, Al-Mg-Si (6xxx series) alloys have been widely applied as lightweight materials for many years because of their excellent specific strength, weldability, and corrosion resistance [1,2]. Considering the physical-chemical characteristics of aluminum alloys, numerous results indicate that some obvious drawbacks such as: large welding deformation, serious joint softening, and low production efficiency would appear during the arc welding process due to the high heat input and low welding speed [3,4,5]. With features of high energy density, low heat input, high welding speed, and large depth–width ratio, laser welding can effectively solve the above problems [6,7,8,9]. Strict accuracy in assembly is required due to the small focused spot diameter of the laser, which significantly limits its application [10,11]
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