Development of design practices for PBF-EB applications in TiAl and Ti-6Al-4V

Quality is an important aspect that directly impacts product performance and reliability. For traditional manufacturing processes, clear regulations have been established to obtain determined quality standards, while, for the newest technologies as the Powder-Bed Fusion with Electron Beam (PBF-EB) there is still a lack of these guidelines. The PBF-EB is an additive manufacturing process that uses an electron beam to selectively melt thin powder layers together. This production technique counts of many advantages, such as design flexibility and the possibility of using high-performance materials that would be too difficult to process otherwise. On the other hand, nowadays, the process still presents some limitations, such as the necessity to use support structures to mitigate deformations. This thesis work aims to establish design practices regarding the use of support structures for the production of overhang features in TiAl and Ti6Al4V. The features investigated include holes, inclined surfaces, flat overhangs, and others, which have been studied using the Design of Experiment (DOE) methodology. Given the large number of features investigated, various models have been designed and organized into separate builds. For each build configuration, a thermal process simulation has been conducted to assess the overall temperature trend in the build and to identify potential issues. The thermal model employed for these simulations was not developed as a part of this thesis work. After being produced, the coupons were measured through a laser scan inspection to evaluate the deviations from the nominal CAD model. These deviation data have been statistically analyzed and the average results compared between the different levels for each feature.