Notch-defect interaction in additively manufactured Inconel 718

Powder bed fusion based additively manufactured components are known to have poor surface quality, especially when building downward facing surfaces, These surfaces can contain defects, from which fatigue cracks can be initiated. In this work the notched fatigue behaviour of Inconel 718 specimens produced by selective laser melting is investigated. The main focus is set on the interaction between notch geometries and local defects due to the amount of overhang in the notch region. Four different geometries are considered, with different amount of notch acuities and degree of downward facing surfaces. A variation in failure sites, with respect to the notch bisector line, was fond in the specimens, and the position was found to be dependent on the amount of overhang and notch acuity. The fatigue life was found to be dependent on the size of surface defects measured in fracture surfaces. Further, the use of average strain energy density as a failure criteria in additively manufactured metals is discussed.