Papers by Keyword: Electron Beam Selective Melting

Abstract: Modeling and simulation in meso-scale have been used to investigate the complicated physics involving powder behaviors during the forming process in electron beam selective melting. But it is difficult to quantitatively predict the forming quality of parts due to the huge calculation amount for multi-layer and multi-pass cases. In this paper, we presented a novel frame for investigating the side surface roughness of fabricated components based on single-track simulation. An integrated model of selective beam melting with considering the random distribution powder particles was developed. The surface morphologies of simulated tracks were used to calculated the surface roughness, and the calculated results were validated by experiment data from independent literature. The effects of heat input were discussed in detail. It reveals that the side roughness increases with a lower heat input. The mechanism behind is the fluctuation of tracks induced by the asymmetry of molten pool, which is related to the coalescence of melting particles and unevenness of powder distribution.

Abstract: In titanium alloys it is known that in bulk sections the solidification conditions in ALM commonly lead to undesirable, coarse, columnar β grain structures. Here, we have investigated the effect of build geometry on the grain structure and associated texture in Ti-6Al-4V ALM components produced by Selective Electron Beam Melting (SEBM). Through reconstruction of the primary β-phase, it has been confirmed that in thick sections large columnar β grains grow with a strong <001>_β fibre texture, although there is a significant skin effect. In contrast, in thin walls nucleation off the surrounding powder and growth inwards dominates. Local heterogeneities are also observed within section transitions. It is shown that the weaker α transformation texture arises from a random distribution across the possible habit variants.