Characterisation of IN718 Nickel Superalloy - Powder Bed Fusion Laser Additive Manufacturing

The proposed research investigates additively manufactured Ni-based superalloy Inconel 718 subjected to two distinct post-processing routes: Ageing heat treatment and Hot Isostatic Pressing (HIP). A comprehensive characterization was carried out using optical microscopy, SEM imaging, EDS analysis, porosity quantification, grain size measurements, NbC volume fraction analysis, and Vickers hardness testing. The study aims to establish correlations between processing pathways, resulting microstructures, and their influence on mechanical performance, with particular focus on hardness and fatigue behavior. Since the fatigue reliability of LPBF-produced Inconel 718 is strongly limited by microstructural character, the results highlight that lower porosity, moderate grain size, and a controlled NbC distribution contribute to enhanced hardness and fatigue life. Among the examined conditions, sample C3 (Heat treatment and HIP) exhibited the most favorable fatigue performance, while sample B7 (Heat treated) had the lowest fatigue life.