| Abstract Scope |
High strength aluminum (Al) alloys (2024, 6061, 7075) alloys are favored in the aerospace and transportation industries for their high strength to weight ratio. The current limitation for these alloys is the inability to use matching filler materials in welded structures due to their high susceptibility to solidification cracking and consequent loss of strength. To remedy this issue, new consumables enhanced with ceramic particles, also called nanoparticles (NP), have been and are being developed that promote the nucleation of fine, equiaxed grains during deposit solidification. This grain structure subdues solidification cracking in welding and Directed Energy Deposition (DED) Additive Manufacturing (AM) builds.
This study evaluated the DED printability of these inoculated alloys using pulse and reciprocating wire feed (RWF) gas metal arc GMA processes. The influence of nanoparticles and metal transfer behavior on strengthening mechanisms is being developed for NP6061, NP2024, and NP7075 consumables. Single-pass per layer walls were constructed using pulse and RWF GMA waveforms. For NP6061, half of each DED build was post-build heat treated to the T6 condition while the other half was evaluated as-deposited. The NP6061-T6 deposit build material exceeded the ultimate tensile and yield strength requirements for wrought 6061-T6.
Progress on ongoing work will be presented on printability of NP6061, NP2024, and NP7075, the effects of GMA versus gas tungsten arc (GTA) metal transfer, and process-feature-microstructure-strengthening relationships for these alloys. Characterization will include optical microscopy, energy dispersive X-ray spectrometry (EDS), SEM, and TEM. Tensile and hardness tests will compare deposit build mechanical properties to base material requirements. Overall, initial results show significant potential for improving the weldability and printability of high strength aluminum alloys. |