Vibration‐based bending fatigue of additively manufactured alloy 718 with varied surface conditions

Abstract Surface roughness is a dominating factor in the fatigue failure of structural components. This is especially true in additive manufacturing (AM), wherein as‐printed surfaces are particularly rough. This work uses a vibration bending fatigue method, which determines the fatigue life of metals at resonant frequencies. The fatigue behavior of AM nickel superalloy 718 fabricated using laser powder bed fusion is investigated with varying surface conditions, processing parameters, and an internal channel. The results indicate that as‐printed surface roughness does not strongly affect vibration bending fatigue life when compared to polished specimens. Fracture surface analysis is performed to determine crack initiation locations, highlighting that most failures initiated from the corners of the rectangular specimens. The outcome of this work is an enhanced understanding of fatigue failure in AM parts with as‐printed surfaces, which is an important step in increasing the efficiency and reliability of AM for applications involving fatigue loading conditions.