Effects of build orientation and inclined features on physical, microstructural and mechanical properties of powder bed fusion additively manufactured metallic parts

In Additive Manufacturing (AM), parts are normally fabricated along the direction perpendicular to the build plate. However, the main axis of the part may differ from this direction, leading to the concept of "build orientation" that is an essential aspect in Design for AM (DfAM). Build orientation defines the required support structures, that in turn affects build time, material waste, and part's surface and mechanical properties. The present paper reviews the literature, focusing on the most utilized Powder Bed Fusion (PBF) techniques in metal AM. The findings are categorized based on properties affected by build orientation. First, manufacturability, geometrical accuracy, surface roughness, and porosity are reviewed. Then microstructural analysis, mechanical properties such as hardness, tensile strength, fatigue strength and fracture toughness are explored, followed by wear and corrosion properties. Consistent attention is given to studies describing the effects of build orientation on efficiency and applicability of post-processing techniques. Critical discussion of results highlights build orientation as a major factor to be considered in design and evaluation of PBF. In addition, prospects for the field are outlined, including the necessity of creating DfAM guidelines regarding build orientation, for which the current work is intended to serve as a starting point.