Laser and Hybrid Laser-MIG Welding of 6.35 and 12.7mm Thick Aluminium Aerospace Alloy

Fusion welding of 7xxx aluminium alloy plates has been investigated for aerospace applications using autogenous laser welding and hybrid laser-MIG welding. Nd:YAG and Yb-fibre lasers have been used, with two different focussed spot sizes in each case. Autogenous and hybrid welding of 12.7mm thick plate using the Yb-fibre laser with a 0.6mm diameter spot was selected for further development, on the basis of penetration and weld quality achieved. These welds were acceptable to the highest quality class B (stringent) of BS EN ISO 13919-2:2001, with a porosity of only 0.3% of the cross-sectional area of the weld, and close to class A of AWS D17.1. Transverse proof strengths of ~60% of parent material were achieved. Development of hybrid welding is ongoing with novel fillers to refine weld metal grain structure and improve weld properties.