Comparison of life prediction methods for net-shape IN718 manufactured by L-PBF

The aerospace industry is increasingly considering metal additive manufacturing (AM) technology to produce optimized components that offer high design flexibility, complex geometries, and reduced weight. However, the surface quality and orientation of printed components remain critical factors influencing their fatigue life. This research aims to assess the impact of different surface qualities, including orientation and post-processing treatments, on the fatigue behaviour of a nickel-chromium alloy (Inconel 718) manufactured via laser powder bed fusion (L-PBF). The study examines key surface related variables that affect the fatigue strength of L-PBF parts, i.e., surface roughness and sub/near-surface anomalies, identifying the anomalies that predominantly contribute to failure across various surface qualities. A life prediction model is developed to accurately estimate fatigue life by integrating the influence of anomaly characteristics associated with specific surface treatments and orientations.