Tensile Properties of Inconel 718 Produced by LMD-Wire

Abstract

The anisotropyAnisotropy in tensile propertiesTensile properties of Wire Laser Metal Deposited Inconel 718Inconel 718 (LMD-w)LMD-w has been investigated from room temperature up to 750 °C at a strain rate of 5.0 10–4 s−1. These properties have been investigated along, at 45° and perpendicular to the building direction. Moreover, different heat treatmentsHeat treatment have been used: as-built, solution heat treated to dissolve Laves phasesLaves phases, solution treated + aged to trigger γ′/γ″ precipitationPrecipitation and direct-aged. According to this extensive characterization of tensile propertiesTensile properties, complemented by SEM and EBSD characterizations, it is shown that, whatever the temperature, Yield stress and tensile resistance have a very weak anisotropyAnisotropy and that tensile propertiesTensile properties are mostly dependent to the prior heat treatmentHeat treatment state. The anisotropyAnisotropy is mostly observed on elastic properties, due to a pronounced crystallographic texture inherited from the directional thermal gradient during the building process. Moreover, Laves phasesLaves phases do not seem to have a strong impact on tensile propertiesTensile properties for this coarse grain material. Tensile strength in such an LMD-processed Inconel 718Inconel 718 is mostly controlled by the γ′/γ″ precipitationPrecipitation and stored “processing” dislocations. A loss of tensile ductility has been evidenced at 750 °C, due to grain boundary oxidation.