Influence of Contouring and depth of machining on tensile properties of Inconel 625 made by Electron Beam Melting

This research is to evaluate the manufacturability and to characterize the performance of Inconel 625 (IN625) by electron beam melting (EBM). After further modifying the commercial EBM parameters for Inconel 718, such as speed function for hatching and the line offset for both hatching and multi-beam contouring, nearly full dense samples (over 99.7% of the wrought material) are produced. It is shown that no contouring strategy generates a relatively rougher surface (approximately 29% in average) compared to the samples printed with contour, requiring even a further post-process machining. Furthermore, the microhardness after EBM is comparable to as-rolled and annealed IN625 material. The samples machined from bulk specimens exhibit good tensile properties regardless of the contouring strategy due to the high depth of machining (5.5mm). However, for the near-net shaped specimens with only 2.1 mm machining of the surfaces, elongation is significantly affected by the contouring strategy. This is in such a manner that the contoured near-net shape parts show relatively 32% less elongation compared to the samples without any contour. Accordingly, multi-beam contouring is better to be avoided to reach tensile properties comparable to the wrought material after a shallow machining, despite the fact that it can lead to a relative smoother surface finish after EBM.QC 20200204