A Review of the Anomalies in Directed Energy Deposition (DED) Processes & Potential Solutions - Part Quality & Defects

Directed Energy Deposition (DED) processes allow additive manufacturing and repair of metallic components with generatively-designed complex geometries, and excellent compositional control. However, its applicability and adoption have been limited when compared to powder bed fusion (PBF) because several issues and anomalies innate to the process are yet to be suitably understood and resolved. This work catalogues and delineates these anomalies in the DED process along with their causes and solutions, based on a state-of-the-art literature review. This work also serves to enumerate and associate the underlying causes to the detrimental effects which manifest as undesirable part/process outcomes. These DED-specific anomalies are categorized under groups related to the part, process, material, productivity, safety, repair, and composition; this paper will specifically report on the first group - part quality and defects, which is further sub-classified into geometrical, morphological and microstructural anomalies. Altogether, this primer acts as a guide to best prepare for and mitigate the problems that are encountered in DED, and also to lay the groundwork to inspire novel solutions to further advance DED into mainstream manufacturing.