Relating porosity to fatigue failure in additively manufactured alloy 718

Additive manufacturing (AM) has the potential to revolutionize the way parts are designed and manufactured; however, AM also produces defects that influence the performance of the components. In order to ensure the quality of the manufactured parts, the processing-structure-property-performance (PSPP) relationship must be understood. In this study, the porosity created during the AM process is investigated, and its influence on performance is quantified with respect to the PSPP framework. Test specimens were fabricated with different processing pedigrees, and the porosity populations within each specimen was characterized. The fatigue life of the specimen was predicted based on the size and location of porosity using a fatigue crack growth approach. Results show that the fatigue life can be successfully predicted, when the appropriate crack growth behavior is used. The insight gained in this study will inform future AM fatigue studies and will lay the groundwork for design and qualification of fracture-critical AM components.