Additive manufacturing of fatigue resistant austenitic stainless steels by understanding process-structure?property relationships

The limited understanding of additive manufacturing process-structure?property inter-relationships raises some concerns regarding the structural reliability, which limits the adoption of this emerging technology. In this study, laser beam-powder bed fusion is leveraged to fabricate an austenitic stainless steel with a microstructure containing minimal known crack initiation features. Ex-situ microstructural observations of the crack initiation features and mechanisms are carried out for interrupted fatigue tests via electron backscatter diffraction mapping of the micro-cracks. Results show that the additive manufactured stainless steel alloy has improved fatigue resistance compared to its wrought counterpart as a result of the unique microstructural features. Impact statement Using an experimental ex-situ microstructural investigation, the fatigue resistance of additive manufactured 304L stainless steel was shown to be superior to the wrought counterpart by avoiding the typical failure mechanisms.