The present study investigates the microstructural, mechanical, and tribological properties of Inconel 718 alloy produced by selective laser melting (SLM) in relation to heat treatment. The SLM-processed samples received a two-step heat treatment: solutionizing at 1065 °C for 1 h, followed by double aging at 720 °C for 8 h and 620 °C for 6 h. The as-built sample exhibited a grain structure mostly characterized by fine Laves phases, while the hardening phases γ′ ((Ni₃ (Al, Ti)) and γ″ (Ni₃Nb) precipitated during the heat treatment. Following heat treatment, a transformation in crystallographic texture and dislocation density occurred, yielding a random texture and reduced dislocation density, particularly in the XZ direction, attributed to the formation of new grains via recrystallization in the microstructure. The grain size in the XY plane decreased following heat treatment, whereas the texture in the direction remained unaffected. The heat-treated samples had significantly higher tensile strength (1330 MPa vs. 960 MPa) and hardness (530 HV vs. 340 HV) relative to the as-built samples. The wear resistance of heat-treated samples surpassed that of the as-built sample due to enhanced mechanical properties resulting from the fine and dispersed γ′ and γ″ precipitates in the microstructure with heat treatment.

Laser Powder Bed Fusion (L-PBF)—an additive manufacturing technique—enables the manufacturing of high-resolution, complex geometries. However, the process’s steep thermal gradients induce residual stresses that can negatively impact material properties and part performance, often causing cracking, deformation, or compromised component geometry. Consequently, measuring and controlling these residual stresses is essential for successful L-PBF. Several studies have attempted to quantify residual stresses by designing geometries that deform predictably, including the Bridge Curvature Method (BCM). BCM is an indirect measurement approach that evaluates post-production distortion or warpage. It involves cutting a specially designed bridge-type specimen from its substrate, thereby releasing internal stresses and causing physical deformations measured as curvature changes. The magnitude of this curvature correlates with the thermal stresses experienced during fabrication. In this study, we investigate how laser power, scan speed, scan patterns, and second melting strategies affect residual stress and porosity in L-PBF-produced Ti6Al4V bridge-type specimens. Three distinct scan patterns—bidirectional laser scanning (zigzag), unidirectional island scanning (Chessboard 1), and bidirectional island scanning (Chessboard 2)—were each tested in both single-scan and double-scan (second melting) variations. Distortion in the specimens was quantified using BCM and correlated with residual stress levels, while relative density measurements based on Archimedes’ principle were used to determine porosity. The results were analyzed using ANOVA, providing insights and recommendations on how scanning strategies and laser parameters influence residual stress and porosity in Ti6Al4V. As a result, to minimize distortion, the Chessboard 1 strategy is most effective with single pass scanning at a scan speed of 800 mm/s. In contrast, to reduce porosity, the bidirectional scanning strategy yields optimal results with a laser power of 160 W and a scan speed of 900 mm/s.