Influence of discontinuities on additively manufactured material performance

A considerable amount of research has been conducted around the globe on effects of defects, which demonstrates that the anomalies produced in metallic additive manufacturing (AM) can be detrimental to the strength and fatigue performance of the resulting material. This topic is of particular concern in aviation, where reliability of material behavior to support safe flight is critical. One response that is most sensitive to these anomalies is fatigue, particularly in the high cycle regime. Fatigue is sensitive to both the type of anomaly as well as the size, aspect ratio, and density within the material. A complicating factor is that different AM processes, machine parameters, and post-processing including heat treatment can affect both the sensitivity of the material to anomalies and the anomaly population itself. This paper will provides examples where fatigue performance is affected not only as a function of the anomaly size, but also different processing which results in different microstructures.