Characterization of selective laser melted Ti6Al4V TPMS porous structures for biomedical applications

Metal additive manufacturing methods, particularly powder bed fusion techniques like selective laser melting, have revolutionized the production of complex geometries that were previously unachievable using conventional manufacturing methods. Among these geometries, porous structures, especially Triply Periodic Minimal Surface structures, are particularly interesting for biomedical applications. These structures possess an interconnected open-cell configuration and mechanical properties, which closely mimic the architecture and behavior of natural bone. This characteristic is critical in reducing common issues, such as stress shielding in biomedical implants, where mismatches in stiffness between the implant and the surrounding bone lead to bone resorption and implant failure. This experimental study aimed to explore the feasibility of fabricating metallic Ti6Al4V porous structures, using SLM in the bio-acceptable range, and emphasizing their mechanical properties and suitability for biomedical applications. The study examined gyroid and diamond sheet networks with a unit cell size of 2.5 mm and an as-designed porosity of 70 %. The mechanical properties were evaluated according to ISO 13314. Various post-processing treatments, including blasting, ultrasonic cleaning, and heat treatment, were applied, and their effects on these structures' morphological and mechanical properties were assessed. The results were compared with the as-built geometries from the corresponding numerical simulations. The findings demonstrated a notable difference in porosity between the as-built and as-designed structures. Mechanical testing confirmed that the mechanical properties of the porous structures were suitable for biomedical applications, as they closely mimicked natural bone, making them viable alternatives to traditional solid implants. Furthermore, the experimental results aligned well with the numerical simulations. • Gyroid structures matched design densities better than diamond structures. • Heat treatment lowered strength but increased elongation due to phase transformation. • Simulations closely matched experiments, confirming model accuracy. • Mechanical properties showed low sensitivity to unit cell count. • Heat-treated porous structures exhibited improved fracture energy characteristics.