Correlation of mechanical properties to microstructure in Inconel 718 fabricated by Direct Metal Laser Sintering

Several Additive Manufacturing (AM) techniques have been developed to produce a wide variety of parts out of several materials. Inconel 718 is of particular interest due to its extensive use in various components in the aerospace, energy and power generation industries. In order to implement parts created from AM, their properties must be adequate to stand up to the demands of service. In this study, the mechanical properties of Metal Laser Sintered (MLS) Inconel 718 were measured and compared to other AM techniques and conventional methods of producing this material and the effects of precipitate phases on the properties of the alloy are discussed. Four different conditions were compared: 1) Solution and Double Aging (HT), 2) Hot Isostatic Pressing (HIP) + HT, 3) HT + Shot Peening (SP), and 4) HIP + HT + SP. The original anisotropic properties arising from the building process are reduced by the thermal treatments. The HT process produced the highest hardness and mechanical properties while the HIP + HT condition produced similar tensile and elongation values but a much lower hardness and yield stress.