Arola, DwayneMamidala, RamuluPetram, Rohin2026-02-052026-02-052026-02-052025Petram_washington_0250O_29012.pdfhttps://hdl.handle.net/1773/55256Thesis (Master's)--University of Washington, 2025Laser powder bed fusion (L-PBF) has emerged as a highly viable method for manufacturing metal structural components across various industries. However, the inherently rough surfaces and complex morphologies of L-PBF components, particularly those with vertical, upskin, and downskin orientations, necessitate post processing treatments to improve surface finish and integrity. Additionally, heat treatments used to control microstructure and mechanical properties often produce a surface oxide layer that requires removal. In this investigation, cavitation abrasive surface finishing (CASF) was employed to improve the surface quality and remove the oxide layer of LPBF Ti6Al4V components, with specific attention to how build orientation, presence of alpha case, and line of sight effected the ability of CASF to improve the surface texture, introduce residual stress, and remove material. Results showed that CASF reduced the average surface roughness from approximately 5 to 20 μm in the as-built condition (depending on orientation) to as low as 4 μm. The process also imparted compressive residual stresses up to 600 MPa and was capable of removing the alpha case from direct line-of-sight surfaces. Despite these improvements, treatment uniformity varied with surface orientation. downskin surfaces, characterized by higher initial roughness and more extensive coverage of partially fused powder particles were the most challenging to treat. Even after CASF, these surfaces achieved significantly lower compressive residual stress, apparently due to shielding effects of particles that limit cavitation impact. Overall, CASF demonstrated strong potential as a non-chemical alternative for post processing LPBF titanium components, offering both surface smoothing and beneficial compressive stress. However, optimization of treatment parameters is needed to improve uniformity across orientations and to further assess the fatigue performance of treated surfaces.application/pdfen-USCC BYAdditive manufacturingCASFLaser Powder Bed FusionLine Of SightLPBFResidual StressMaterials ScienceMechanical engineeringMechanicsMaterials science and engineeringThesis