The influence of additive manufacturing processing parameters on surface roughness and fatigue life

Abstract Additive manufacturing (AM) is used to create metal components with complex geometries where the internal surfaces cannot easily be post machined. Fatigue behavior in additively manufactured metals is largely driven by defects in the material such as porosity and surface roughness. This work investigates the processing-structure-property-performance (PSPP) relationship for varied contour processing parameters, and the resulting surface roughness features for alloy 718 fabricated using the laser powder bed fusion AM process. Two nondestructive characterization methods are used to determine the relationships between contour parameters and surface roughness characteristics. The benefits of each characterization technique and metrics required for an accurate representation of the additively manufactured surfaces are discussed. Axial fatigue testing is performed to connect the entire PSPP relationship. An understanding of the PSPP relationship with respect to surface roughness features and fatigue life can be used to guide future process parameter optimization and to inform the qualification strategy for AM components.