The influences of Ar-He shielding gas mixture on welding characteristics of fiber laser-MIG hybrid welding of aluminum alloy

During laser or laser-arc hybrid welding process of aluminum alloy, laser power waste and keyhole fluctuation are drastic due to the shielding effect of dense plasma. Consequently, small weld penetration depth and numerous weld porosity defects are produced. In the present work, Ar-He shielding gas mixture was used to improve the weld quality of fiber laser-metal inert gas (MIG) hybrid welded aluminum alloy. The influences of Ar-He shielding gas mixtures with various He volume ratios on plasma temperature, electron density, weld penetration depth and porosity defect were investigated, respectively. The He volume ratio enough for improving the weld penetration depth and suppressing the porosity defect was 50%. The effective laser power density increased with the increasing He volume ratio, which contributed to the increase of weld penetration depth. The weld porosity defects were suppressed efficiently, since the stability of the keyhole was improved while using Ar-He shielding gas mixture.