The Effect of Location and Post-treatment on the Microstructure of EBM-Built Alloy 718

摘要: Additive manufacturing (AM) of Ni-based superalloys such as Alloy 718 may obviate the need for difficult machining and welding operations associated with geometrically intricate parts, thus potentially expanding design possibilities facilitating cost-effective manufacture complex components. However, processing AM builds completely free from defects, which impair mechanical properties fatigue ductility, is challenging. Anisotropic properties, microstructural heterogeneities local formation undesired phases are additional concerns that have motivated post-treatment builds. This work investigates changes specimens produced by Electron Beam Melting (EBM) as-built microstructures at 3 build heights: near base plate, in middle top build. Two different conditions, hot isostatic pressing (HIP) alone a combined HIP solutionising two-step aging were examined compared to results condition. The influence various post-treatments on minor phase distributions (δ, γ″, carbides), overall porosity, longitudinal grain widths Vickers microhardness was considered. treatment led significant reduction porosity dissolution δ phase, appreciable growth both conditions. variation hardness noted function height eliminated after post-treatment. Overall, found decrease increase full HIP, treatment, attributed γ″ during its re-precipitation subsequent heat steps.