Metal Additive Manufacturing Conference - MAMC 2022

By volume, most of the aluminum alloys used in additive manufacturing are either Al-Si based compositions or Airbus’s Scalmalloy. However, Al-Si alloys perform poorly and Scalmalloy is expensive due to the use of Sc. Other high strength aluminum alloys families, such as those of the 7xxx series, have been barely used due to their tendency to hot crack while printing. In this framework, a high strength composition belonging to the 7xxx has been developed to be compatible with the additive manufacturing process.

Dense coupons with this novel composition have been printed using Laser Metal Deposition (LMD). The coupons have been used to tune the heat treatment and evaluate the tensile properties, subsequently. A chemical characterization has been also performed to assess the composition evolution during printing and link the strength with the composition. The results are compared to the cast counterparts.

In addition, repair experiments have been performed on 7xxx substrates simulating the presence of defects or manufacturing errors. To do so, the surface is first prepared before printing and later refurbished with the new composition using LMD. The interactions between the component and the repair, such as the deformation, mechanical properties, microstructures, and sizes of the heat affected zones, are measured depending on the energy density of the tested parameters. The impact of the heat treatment to obtain a trade-off between the properties of the repair and the component is also discussed.