High-fidelity Modeling of Multilayer Building Process in Electron Beam Powder Bed Fusion: Build-quality Prediction and Formation-Mechanism Investigation

High-fidelity simulations of powder bed fusion (PBF) additive manufacturing have made significant progress over the past decade. In this study, an efficient two-dimensional frame was developed for simulating the electron beam PBF process with hundreds of tracks for the direct prediction of the build quality. The applicable parameter range of the developed model was determined by comparing the heat transfer with that in three-dimensional cases. Subsequently, powder deposition and selective melting were coupled for a continuous simulation of the multilayer process. Three powder deposition models were utilized to generate random powder particles, and their effects on the packing structure and the resultant simulated build quality were investigated. The predicted build quality was validated using experimental results from independent studies. By reproducing the building process, the defect development mechanism in a multilayer process was revealed for the coalescence behaviors of randomly distributed powder particles, which also confirmed the importance of simulation at the high-fidelity powder scale. The effects of key process parameters during multilayer and multi-track processes on the build quality were systematically investigated. In particular, the formation statuses of all tracks during the simulated building process were recorded and analyzed statistically, which provided crucial information on the printing process for understanding the building mechanism or performing uncertainty analysis.