Kevin J. Chaput PhD, Research Engineer, Air Force Research Laboratory
This presentation investigates the effect of build geometry on the microstructure in electron beam melted (EBM) Ti-6Al-4V. Through variation in build geometry the extremes in the “optimal” processing window of energy density could be evaluated on two regions in a single build. Microstructural characterization revealed little variation in the size of the features between regions. However, vastly different solidification textures were observed. In contrast to the texture of the beta grains found in higher energy density regions, the low energy density regions exhibited a preferential alignment with the build direction, facilitating a distinctly different texture in the transformed alpha. Tensile tests conducted on specimens extracted from each region showed comparable ductility, but clear differences in yield and ultimate tensile strength. An elementary thermal process model is employed to demonstrate a rationale for the different textures.