Elevated temperature fatigue behavior of notched specimens produced by L-PBF in Inconel 718

The elevated temperature fatigue behavior and notch sensitivity of the Inconel 718 produced via Laser-Powder Bed Fusion (L-PBF) were investigated. A smooth specimen and three geometries of 90° V-notched specimens were employed. The material was printed by employing a set of process parameters aimed at producing a full-dense material and was post-processed adopting a conventional solution and aging heat treatment. Three V-notch geometries were defined through FEM analyses to obtain theoretical stress concentration factors ranging from 1.5 to 3.5. Isothermal HCF tests were carried out at a temperature of 650°C and a load ratio R of 0.1. Fractographic investigations pointed out the features of the crack onset site for the different geometries. Metallographic analyses were employed to assess the effective notch geometry produced by the L-PBF process, as well as the material microstructure.