Abstract
High-efficiency and high-quality welding has always been the focus of welding research. This article proposes a novel double-pulse, triple-wire MIG welding process for the welding of 6082-T6 aluminum alloy. The process characteristics of welding arc and droplet transfer were studied, and the performances of weld formation, morphology, hardness, and tensile strength were tested for the 1 Hz, 3 Hz, and 5 Hz double-pulse welding and normal-pulse welding. It was found that in the welding process, the pulsed arc steadily alternated among three welding wires without arc interruption, and the arc length changed periodically with the double-pulse frequency. The droplets transferred with a stable one-pulse-one-drop mode. Besides, a proper double-pulse frequency, e.g., 3 Hz in this case, was conducive to forming good welds with regular fish-scale patterns and no pores. The tensile strength of the joint could reach 64% of the base material’s tensile strength, and its fracture belonged to plastic fracture, which occurred in the HAZ. This new welding method will have great potential in aluminum alloy welding.
Highlights
Accepted: 26 August 2021Due to its characteristics of low density, high specific strength, good corrosion resistance, electrical conductivity, thermal conductivity, and good mechanical properties at low temperatures, aluminum alloy has been widely used in aerospace, automotive, electrical, chemical, transportation, and other industries [1,2]
Compared with the other welding methods, pulse metal inert gas (MIG) welding has the advantages of low cost and high efficiency, and it is widely favored in production
Welding arc and droplet transfer are important welding process characteristics, which directly determine whether the welding process is good
Summary
Accepted: 26 August 2021Due to its characteristics of low density, high specific strength, good corrosion resistance, electrical conductivity, thermal conductivity, and good mechanical properties at low temperatures, aluminum alloy has been widely used in aerospace, automotive, electrical, chemical, transportation, and other industries [1,2]. The 6082 aluminum alloy, which belongs to the Al-Mg-Si series, is the main structural material used in high-speed railway [3,4]. Welding is an important method for joining aluminum alloys. Because aluminum alloys have too high thermal conductivity, too large linear expansion coefficients, and an oxide film on the surface, they are hard to weld. Welding defects, such as incomplete fusion, slag inclusion, crack, and porosity, appear [5]. Compared with the other welding methods, pulse MIG welding has the advantages of low cost and high efficiency, and it is widely favored in production.
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