Laser-based additive manufacturing (AM) of metallic materials produces high-quality parts with high mechanical strength, but it often requires a long processing time. Shortening the processing time by increasing scanning speed or hatch distance results in greater porosity. Post-densification through hot isostatic pressing (HIP) can reduce porosity and enhance fatigue strength by homogenizing the microstructure. However, HIP cannot completely eliminate argon porosity introduced during the AM process due to its insolubility in metallic materials.
This study investigates the influence of initial porosity on the fatigue strength of IN718 specimens after HIP and different heat treatments, focusing on the impact of argon porosity. Fatigue strength tests were conducted on samples with varying initial porosities introduced by increasing hatch distance. Despite high initial porosity and residual argon content, HIP significantly improved fatigue strength. Samples with lower initial porosity showed no difference in fatigue behavior between aging with or without pressure, while those with higher initial porosity exhibited a significant difference in fatigue strength based on aging conditions.
