Microstructure and residual stress in Ti-6l-4V parts made by different additive manufacturing techniques

Additive manufacturing (AM) also known as solid free form fabrication or additive fabrication, additive layer manufacturing, direct digital manufacturing and 3D printing, is rapidly growing as an advanced manufacturing technology. At present, two major groups of AM techniques, namely powder bed fusion (PBF) and directed energy deposition (DPD), are available. The AM techniques are classified based on the heat source used for the manufacturing process whether it is provided by laser, or an electron beam. Disregarding the AM manufacturing method, the material’s mechanical properties, residual stress level and surface quality are the major limitations preventing the uptake of the technology to produce components for demanding engineering applications. The objective of this study is to obtain more in-depth knowledge of microstructure and residual stress developments in Ti-6Al-4V cylindrical parts made by different AM techniques, and compare the results with parts made through traditional manufacturing practices (i.e. Ti-6Al-4V_ELI). For this purpose, direct comparisons are made between the microstructure and mechanical properties of the materials made by AM techniques and those made by a forging process route.