Dimensional Accuracy of Electron Beam Powder Bed Fusion with Ti-6Al-4V

While much of additive manufacturing (AM) research is focused on microstructure, material properties, and defects, there is much less research in regards to understanding how well the part coming out of the machine matches the 3D model it is based on, as well as what are the key process parameters an engineer needs to care about when they are optimizing for AM. The purpose of this study was to understand the dimensional accuracy of the electron beam powder bed fusion (EB-PBF) process using specimens of different length scales from Ti-6Al-4V. Metrology of the specimens produced was performed using fringe projection, or laser scanning, to characterize the as-built geometry. At the meso-scale, specimen geometry and hatching history play a critical role in dimensional deviation. The effect of hatching history was further witnessed at the macro-scale while also demonstrating the effects of thermal expansion in EB-PBF. These results make the case for further process optimization in terms of dimensional accuracy in order to reduce post-processing costs and flow time.