Notch-defect interaction in additively manufactured Inconel 718. (May 2019)

• Record Type: Journal Article
• Authors: Solberg, K.; Berto, F.
• Is Part Of: International journal of fatigue. Volume 122(2019)
• Page Start: 35
• Page End: 45
• Publication Date: 2019-05
• Subjects: Fatigue -- Additive manufacturing -- Fracture -- Defect -- Surface; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2018.12.021
• Languages: English
• ISSNs: 0142-1123

Abstract

Graphical abstract: Highlights: Specimens fail from defects in surfaces build facing downwards. Size of measurable defects in fracture surface is related to the fatigue life. A diagram relating the position of failure initiation site to the notch acuity is proposed. Average strain energy density failure criteria is able to predict fatigue life for sharp notches. Abstract: 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.