Impact of Process-Induced Microstructure and Surface Roughness on the Compressive Deformation and Failure Behavior of Ti-6Al-4V Lattice Structures: LPBF vs. EBPBF

Ti-6Al-4V lattice structures fabricated by powder bed fusion exhibit compressive responses governed by topology and process-induced material state. This study compares Auxetic, Dode-thin, and Tesseract lattices manufactured by laser powder bed fusion (LPBF) and electron beam powder bed fusion (EBPBF). Surface roughness was measured by confocal laser scanning microscopy, microstructure and texture by OM/EBSD, and compression behavior by quasi-static testing and finite element models (FEM), including strut models with measured surfaces. EBPBF struts were rougher than LPBF struts, with R a values of 35.54 and 15.48 μm, respectively. LPBF showed fine acicular α′-like laths, whereas EBPBF showed coarser α+β-like lamellar colonies. LPBF exhibited higher first local peak stresses, particularly for Auxetic and Tesseract, with LPBF Tesseract reaching 229 MPa. Initial collapse resistance did not directly determine energy absorption. LPBF Dode-thin achieved the highest nominal specific energy absorption (SEA) of 6.94 J g −1 at its individual energy-efficiency-based strain limit, whereas LPBF Tesseract had the highest nominal SEA (3.35 J g −1 ) at a common 15% strain. Nominal-geometry lattice FEM overestimated experimental first peak loads by factors of 1.43–2.03. Scaling by a load-bearing diameter d − R z reduced FE/test first-peak ratios to 1.04–1.10 for five of six lattices. Measured EBPBF strut surfaces reduced peak bending moments by 6.6–10.5%, compared with 1.6–3.5% for LPBF surfaces. These results indicate that topology, material state, and surface condition jointly influence lattice compression.