Stress-defect-life interactions of fatigued additively manufactured alloy 718

Abstract

Defects in additively manufactured alloys commonly reduce fatigue life, and traditional S-N portrayals of the data provide little insight into failure mechanisms. Closer observation of failure-inducing defects show, however, that the debit is directly related to the defect size and location. In this work, scatter in both literature and experimental S-N data is reduced using Murakami’s stress intensity factor equation, and El-Haddad’s fatigue limit framework is leveraged to predict finite life of components. Scatter in S-N fatigue data becomes highly predictable, and relationships between pore size, applied stress, and fatigue life are clearly defined for defect tolerant design efforts.