Among various metal additive manufacturing (AM) technologies, L-PBF is known for fabricating intricate components. However, due to step edges and powder particle attachments, attaining a good surface finish is challenging, especially on downskin surfaces. Contour scanning has potential to improve surface quality because such scanning may dominate the surface formation of sloped features. This study evaluates the effects of pre- and post-contouring strategies on the sloped downskin surfaces fabricated using a commercial L-PBF system with Ti6Al4V powder. L-PBF parts printed at inclination angles 30°, 45° and 60° were investigated. A double-contouring approach with varying processing conditions was employed and surface characteristics were analyzed using data acquired by white light interferometry. The average surface roughness, S_a, surface skewness, S_sk, and percentage area of powder particles attached onto surfaces were statistically evaluated. The lowest S_a obtained for pre- and post-contoured samples is 14.08 µm and 18.88 µm, respectively. For both strategies, the combination of a low laser power and a high scan speed on the interface of downskin surface and underneath powder results in smoother surfaces. However, while comparing both strategies, pre-contouring gives better surface finish for samples built at similar processing conditions, with a difference of nearly 5 µm in S_a.

Laser powder bed fusion (L-PBF) enables the fabrication of complex lattice-type structures composed of thin struts, offering lightweight, high-strength advantages in aerospace and biomedical applications, among others. While extensive research has examined full lattices and process parameter effects individually, the combined influence of strut geometry, configuration, and processing conditions on mechanical properties remains less understood. This study investigates how the strut number, strut size, cross-sectional shape, and laser energy input affect the mechanical properties of thin-strut L-PBF tensile specimens. Ti-6Al-4V struts were designed and fabricated using an EOS M270 system using five linear energy density (LED) levels. The fabricated specimens were measured in porosity using micro-scaled computed tomography and further evaluated using a tensile tester. The results showed that increasing the strut number leads to significant reductions in tensile strength, even with the same overall cross-sectional area, especially at low LED levels. Size effects on mechanical strengths were observed, though mostly minimal, except at the smallest strut size, where defects tend to be more critical. Circular and square shapes performed similarly under general LED conditions; however, square struts exhibited inferior behavior at the lowest LED level. Overall, LED is the most influential factor, with the greatest tensile strength occurring near 0.2 J/mm; further decreasing or increasing the LED both increase the porosity, degrading mechanical strengths.

Porosity in laser powder bed fusion (L-PBF) lattice struts remains poorly understood, as the effects of build angle and process parameters are often studied separately. A full factorial design of 27 configurations combined three build angles (40–70°), three strut sizes (0.25–1.25 mm), and three linear energy densities (LED: 0.23–0.35 J/mm). Specimens were fabricated in Ti-6Al-4V on an EOS M270 system and characterized by micro-computed tomography (µ-CT). Statistical analysis showed that all three factors influenced porosity percentage (P%), with a significant size–LED interaction, while only strut size and LED influenced the average volume of individual pores (PV_avg), with no significant interactions. P% rose 194% as strut diameter increased from 0.25 to 1.25 mm, climbed steeply between 0.23 and 0.29 J/mm before plateauing, and fell 19% as build angle increased from 40° to 70°. PV_avg rose 160% across the LED range and 37% with strut diameter. Spatial segmentation showed that the median down-skin-to-up-skin pore volume ratio in the larger struts fell from 2.0 at 40°, that is, twice the pore volume in the DS region, to 1.3 at 70°. This asymmetry was absent in the 0.25 mm struts, where low pore counts made the metric unreliable.