Descripción
Project Description Powder Bed Fusion by Electron Beam (PBF-EB) normally aims to produce components with high density. However, productivity may be improved by creating only a gas-tight outer shell around a sintered or semi-melted porous core, followed by Hot Isostatic Pressing (HIP). In PBF-EB, internal pores are formed under vacuum, which is favorable for pore closure during HIP provided that the shell remains gas-tight. Previous studies in both PBF-EB and PBF-LB have demonstrated the feasibility of shell-core concepts, although validation for more complex geometries remains limited.[1],[2] If HIP is already required, the approach reduces energy input, build time, cost, and evaporation of sensitive alloying elements. The key challenges are to identify stable process parameters, verify shell integrity, and quantify porosity, densification, and dimensional shrinkage. This master thesis will focus primarily on experimental work in the PBF-EB printer. The student will evaluate a limited set of process parameters to produce test parts with a dense shell and a porous sintered or semi-melted core. Samples will be characterized before and after HIP to determine process stability, shell integrity, density, pore morphology, microstructure, and dimensional change. The work will generate an initial dataset for shrinkage compensation and include a limited finite element modelling (FEM) task to predict and compensate shrinkage. The aim is to determine whether a shell-core PBF-EB strategy can shorten build time while producing preforms suitable for HIP consolidation, and to establish an initial method for compensating predictable shrinkage. The scope is sized for one 30-credit master thesis: one material, simple coupon geometries, a few iterative test prints, 1-2 HIP cycles, basic sample characterization, FEM shrinkage modelling, and printing a more complex shape to evaluate the developed model and process parameters. Full constitutive model development, extensive mechanical qu