The drive toward sustainable manufacturing has increased interest in repurposing metal scrap as a feedstock for powder production. Previous work shows scrap-derived powders can produce parts with mechanical properties comparable to virgin feedstock, but has focused largely on gas atomization (GA). Alternative atomization routes, such as ultrasonic atomization (UA), remain underexplored.

This thesis characterizes wire-derived UA SS316L as a feedstock for laser powder bed fusion (LPBF), comparing directly with a commercial GA powder. A UA process window was first established through Archimedes density and image analysis of cubes. The densest UA parameter set was then applied to both feedstocks to fabricate cube, tensile, and hardness specimens under two scan strategies (67° and contour), and BCC lattices under 67°. Cubes were characterized for porosity, microstructure, crystallographic texture (EBSD), and phase composition (XRD). Mechanical performance was evaluated through tensile testing, Vickers hardness, and lattice compression. Powder reuse was assessed over five successive builds.

Both feedstocks achieved relative densities above 99%. Across both scan strategies, UA specimens showed slightly lower yield and ultimate tensile strengths than GA with slightly higher ductility, though the differences were modest. Feedstock type had limited influence on grain morphology, whereas scan strategy strongly affected crystallographic texture. Tensile and hardness values for all specimens fell within the range typically reported for LPBF SS316L. UA-derived BCC lattices exhibited compressive response comparable to GA counterparts. After five reuse cycles, UA powder exhibited only limited degradation in feedstock and part properties.

Overall, wire-derived UA SS316L is shown to be a viable LPBF feedstock for dense bulk components and BCC lattice structures. These findings provide a useful foundation for future work on ultrasonic atomization as a scrap-based route for metal AM feedstocks. ... Read more