Microstructure and Mechanical Properties of Pulse MIG Welded Joint of AlMg/6082 Dissimilar Aluminum Alloy
LI Jia1,2,*, HUANG Li3, RAN Qihong4, GAO Feng4
1 Department of Mechatronics and Vehicle Engineering Chongqing Jiaotong University, Chongqing 400074, China 2 Department of Electrical Engineering, Chongqing Industry Polytechnic College, Chongqing 401122, China 3 China Automotive Engineering Research Institute Co., Ltd., Chongqing 401120, China 4 Chongqing Changan Automobile Co., Ltd., Chongqing 400023, China
Abstract: The joining between AlMg cast aluminum and 6082-T6 aluminum alloy was conducted with pulse MIG welding technology. The mechanical properties, grain morphology, and fracture morphology of dissimilar aluminum alloy joints between AlMg cast aluminum and 6082-T6 aluminum alloy profiles were studied. The influence of microstructural evolution on mechanical properties was analyzed. The results shows that the maximum tensile load of the 6082/AlMg welded joint is up to 3 235 N, up to 85.5% of the load-bearing capacity of AlMg base material. The elongation is 8.2%, and the welding coefficient is approximately 0.8. The joints breaks in the AlMg base material and shows a ductile fracture. In the heat-affected zone on AlMg side, the lowest microhardness value is 77HV, with only a 7% decrease compared to the AlMg base metal. There is no significant softening observed, indicating a low sensitivity to the welding thermal cycle. However, the heat-affected zone of 6082-T6 side exhibits significant softening, with a 32% decrease in hardness relative to the base metal. This softening is attributed to the reduced density of β″ precipitates and the formation of larger β′ precipitates, which provided weaker strengthening effects. The weld zone, undergoes rapid cooling during welding, has an equiaxed dendritic cast structure with uneven solute distribution. Under the influence of the welding thermal cycle, the heat-affected zone on both sides of the joint shows varying degrees of grain growth. The AlMg side near the weld zone exhibits a 42.8% increase in grain size compared to the base metal.
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2025, Vol. 39 
