Abstract Scope |
Additive friction stir deposition is an emerging solid-state additive process that potentially addresses the quality control issues in beam-based metal additive manufacturing via high-temperature, rapid plastic deformation, which typically results in fully-dense material with equiaxed, fine grains in the as-printed state. Here, we explore the underlying deformation insights by integrating tracer-based experiment with process modeling. Using Al-Cu/Al-Mg-Si as the tracer/base material system, we employ X-ray computed tomography to unravel the plastic deformation path of the center and edge voxels in the feed material. The millimeter-scale cylindrical tracers are found to experience extrusion and torsion, followed by shear-induced thinning, ultimately forming micro-ribbons piling up along the deposition track. Microstructure mapping throughout the deformation path indicates significant grain refinement during initial material feeding via geometric dynamic recrystallization. Additional insights on the strain rate, total strain, flow stress, and Zener-Hollomon parameter at each deposition step are revealed through experiment-validated computational fluid dynamics modeling. |