Effects of Process Parameters on Microstructure and Properties of Indirect Heating Electron Beam Welded 5083/5052 Aluminum Alloy Dissimilar Metal Joint

The 5083 aluminum alloy and 5052 aluminum alloy were butt welded by indirect heating electron beam welding. The effects of beam current intensity （18, 20, 22 mA） and welding speed （800, 1 000, 1 200 mm·min⁻¹） on the formation quality, microstructure and tensile properties of the weld joint were studied. The results show that with the increase of beam current intensity, the weld seam collapsed and the formation quality deteriorated. With the increase of welding speed, the weld fusion depth decreased and the degree of collapse reduced. Under different process parameters, the weld structure mainly consisted of α-Al and β-Mg₂Al₃ phases, and there were also Mg₂Si phases. With the increase of beam current intensity, the β phase grains coarsened, and the precipitation amount of Mg₂Si strengthening phase in the weld zone increased, and the Al-Mn dispersion phase was formed. With the increase of welding speed, the precipitation amount of β phase and Mg₂Si phase decreased. With the increase of beam current intensity, the tensile strength and yield strength of the joint increased, and the tensile fracture mechanism changed from brittle fracture to ductile fracture. With the increase of welding speed, the tensile strength increased, the yield strength first increased and then decreased, and the tensile fracture mechanism changed from ductile fracture to brittle fracture.