Optimization of sintering phase in EB-PBF process for metallic alloys component production

In the last few years, additive manufacturing (AM) is gradually becoming popular in industrial applications. However, the development is still limited by the current optimization methods largely still based on a “trial and error” approach. Despite its proven effectiveness, this methods has considerable downsides such as high cost for materials and energy along with been a heavily time-consuming method, and especially does not provide a deep understanding of the process. The gradual evolution of computational power, along with the emergence of new methodologies, boosted development of tailored simulations to accelerate the process development and replace the extensive use of “trial and error”. In AM, the literature work on simulations are mainly focused on the melting step. However, in particular processes such as electron beam powder bed fusion (EB-PBF), the simulation of the meting phase provide incomplete information about the process feasibility. The preheating serves as step to create connection between the particle, called neck, which in turn increase the electrical and thermal conductivities. This thesis aims to simulate this stage to identify which parameters can be adjusted to obtained the proper powder particles connection to prevent process fail. Thanks to the phase-field method, systems of particles has been modelled obtaining relevant results without excessive complexity and computational cost. A Design Of Experiment has been developed to investigate how diameter particles and diameter ratio influences the dimension of the neck. Then, the rigid-body motion mechanics has been considered attempting to connect its parameters to the neck dimension. Lastly a real case study has been examined to test and validate the efficiency of the developed model. Thanks to these simulations, a better understanding of the link between powder geometry and sintering effects has been achieved, proved by the match obtained between the simulation results and the real case study measurement.