EBM Development on Inconel 718 for Use in Aerospace Components

The Electron Beam Melting (EBM) additive manufacturing process builds complex parts out of metal powders within a high temperature and vacuum environment. EBM has been used in final production for many years, and more than 40,000 EBM devices have been implanted for the medical industry.  In recent years EBM has started to gain momentum in the aerospace industry to manufacture production components.  In order to expand the EBM market, new materials such as Inconel 718 have been developed and characterized in the EBM technology. Inconel 718 is a nickel-chromium based super alloy ideal for high temperature and corrosive environments, with excellent mechanical properties at high temperatures.  Several Inconel 718 powders, exhibiting different morphologies and derived from different manufacturing routes, were tested to see which powder would provide the best results in the EBM process. Build themes were developed and evaluated to produce fully dense parts with minimized build time.  In order to enhance the Inconel 718 properties, the as-built material has to be hot isostatic pressed to dissolve precipitates and then solution annealed to precipitate harden strong, metastable gamma double-prime structure. A post processing treatment was developed to optimize the mechanical properties, which includes hot isostatic pressing, solution treating, and an aging cycle. The build components were characterized by optical microscopy, micro hardness, and mechanical testing.