Additive manufacturing of AISI 316L specimens with distributed inner bone-type cavities: processability and characterization

Bone lacunae are cavities the morphology of which strongly affects the damage propagation inside bone. Nevertheless, the role of eventual variations in their morphological features is not clear yet. In this scenario, the work aims at isolating the effects of lacunar-like pores on the mechanical response of 3D printed samples. The research presents a detailed study on the processability of those cavities by means of laser powder bed fusion process, carefully considers both drawbacks of the process, such as the need of heat treatment to minimize the residual stresses, and the limitation of design constraints, such as the presence of metallic powders trapped inside closed cavities. The identification of the optimized heat treatment is permitted both by X-ray diffractometer analysis and morphological examinations by means of optical and micro-CT investigations of cavities. The selected heat treatment is performed on tensile test samples with lacunar-like cavities to progress with a preliminary mechanical static characterization. Future developments will investigate the fracture modality, both under static and fatigue loadings to comprehend how cavities with different morphology influence the damage propagation.