Partial penetration laser-based welding of aluminum alloy (AA 5083-H32)

Partial penetration autogenous-laser welding of an aluminum alloy (AA 5083-H32) is studied. The formation of porosity and its mitigation during the autogenous-laser welding of the aluminum alloy in a thick butt-joint configuration were investigated. The influence of the process parameters (welding speed, laser power, surface treatment by cold plasma, and shielding gas) was studied by the characterization techniques. A finite element analysis was also applied to investigate the thermal history of the autogenous-laser welding process to join the aluminum alloy. The welds were characterized by an optical profilometer, optical microscope, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and microhardness tester. The online monitoring of the laser welding process was performed by a charged coupled device (CCD) camera. The results showed that the welds prepared by the protection of the helium as the shielding gas at a low welding speed could mitigate the porosity during the autogenous-laser welding process. The numerical study demonstrated that the peak of the temperature was occurred in the fusion zone (FZ). The heat affected zone (HAZ) has shown grain growth, formation of Al6 (Mn,Fe), and dendritic structure. The formation of the porosity was attributed to the entrapment of the shielding gas caused by collapse of the keyhole.

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