Effect of build orientation and post processing methods on the mechanical properties of EB-PBF of unalloyed copper

Mechanical properties of materials are mostly influenced by the microstructure of the metal. Different microstructural evolution of materials has been attainable with the introduction of Additive manufacturing (AM) to the world of production. In this study, the influence of microstructure on mechanical properties of unalloyed copper was investigated by fabricating samples in three different orientations ( perpendicular, parallel and 45° to the build direction) using Electron Beam Powder Bed Fusion process and randomly assigning them to three post processing conditions common to AM parts; as-fabricated, hot isostatic pressing (HIP) and vacuum annealing. Mechanical testing performed via room temperature showed that the lowest elongation and highest tensile strength values as a result of dislocation of the epitaxial columnar grain movement during testing for the samples perpendicular to the build direction in the as-fabricated condition. In general, the post-process parameters used for the HIP and vacuum annealed samples slightly improved the density of parts and reduced the oxygen content respectively. In addition, fracture surfaces are analyzed using the scanning electron microscope (SEM) to also the investigate the effect of the inclusion type (oxides, pore sizes) on the mechanical properties. An electron backscattering diffraction (EBSD) analysis was performed before and after to investigate the microstructural changes and fracture damage behavior of the unalloyed copper.