Additive manufacturing processes for metals and effects of defects on mechanical strength: a review

Abstract Additive manufacturing (AM) technologies are appreciated all over the world for their great versatility, including the possibility to realize very complex shapes in one step, increasing the design freedom and significantly lowering the production costs. There are different AM processes and the criterion used to classify them is not unique; however, the most common AM technologies for metals can be broadly classified into two categories: Powder Bed Fusion (PBF) and Directed Energy Deposition (DED). Both induce defectiveness in the component, such as concentrated residual stresses, surface roughness, delamination, porosity, and Lack of Fusion (LOF) defects that decrease mechanical resistance and lead to poor fatigue life behavior. The aim of this work is to provide a full overview of AM defects with the associated damage mechanism. The work is completed with a description of the process parameters optimization to minimize the induced defects.