Mechanical Behavior of Aluminum Alloys Processed with Additive Friction Stir-Deposition
By J. Brian Jordon (The University of Alabama), Dustin Avery (The University of Alabama), Ben Rutherford (The University of Alabama), Paul Allison (The University of Alabama)

The AFS-Deposition process is a novel method that exploits high-shear and severe plastic deformation to produce fully-dense, near net-shape structures. To produce additive components by the AFS-Deposition process, feedstock material is deposited through a hollow rotating tool that generates frictional heat and hydrostatic pressure, which results in solid-state metallurgical bonding. In this work, the microstructure of AFS-Deposition of AA6061 is investigated and compared to the feedstock material. Analysis of the AFS-Deposition revealed refined and equiaxed grain structure that produced nearly isotropic monotonic mechanical response. In addition, fatigue tests were conducted under strain control conditions and results show that the AFS-Deposition AA6061 compares well to the wrought feedstock due to the dynamically recrystallized microstructure and the lack of porosity commonly found in beam based additively manufactured materials. Post mortem analysis of fractured samples suggest that AFS-Deposition material exhibits fatigue crack nucleation and crack propagation mechanisms similar to wrought AA6061.