Additive manufacturing (AM), particularly Metal Laser Powder Bed Fusion (PBF-LB/M), has enabled the production of complex, high-performance components for safety-critical applications such as turbo-engines. However, the qualification of AM materials, especially those exposed to loading conditions at high temperature, presents significant challenges due to the unique nature of AM processes. These materials, such as the Ni-based alloys IN738LC or IN718, often exhibit variations in microstructure depending on parameters like build orientation, geometry, and post-processing steps. To test and assess their long-term performance under service conditions with standard practices would result in time and cost invensive experimental campaigns.

This talk presents an overview of advanced materials testing approaches aimed at addressing these challenges, with a focus on components subject to both creep and fatigue loading at high temperatures. The development of a Specimen Extraction Cube (SEC) for extracting samples from different build orientations, allowing for comprehensive mechanical testing and the correlation of material properties with heat-treated microstructures is showcased. This method enables insights into the effects of build orientation and component design features on properties such as creep strength and creep deformation rates.

Further, the qualification of PBF-LB/M materials for high cycle fatigue loading, based on fracture-mechanics based approaches rather than intensive S-N-curve data acquisition is presented. To assess life of such components, especially under high-cycle fatigue loading, the behavior of short cracks below the long crack threshold ΔK is of paramount importance. The talk highlights a model approach based on cyclic R-curves that addresses the transition between short and long crack growth and improves the prediction of crack propagation in complex, high-temperature conditions. Additionally, we will explore the role of crack closure mechanisms, such as plasticity, roughness, and oxide-induced closure, in arresting crack growth and their impact on material performance. This model is demonstrated for IN718 alloy at 650°C, using cyclic crack growth tests under varying load ratios and environmental conditions, including air and vacuum.

By combining these testing techniques with microstructural investigations, NDT inspection techniques and in-situ monitoring during build processes, the findings from this research contribute to the development of more reliable methods for qualifying additively manufactured components for high-temperature service, ultimately reducing time-to-market for new designs while ensuring their long-term performance in demanding applications.