Notched fatigue of additive manufactured metals under axial and multiaxial loadings, Part I: Effects of surface roughness and HIP and comparisons with their wrought alloys

Abstract Additive manufacturing (AM) technology has grown significantly in recent years, as an alternative manufacturing technique to conventional fabrication methods. However, fatigue behavior of AM metals is still not well understood, limiting their applications for critical load carrying components. This is particularly true when component-like features such as geometrical stress concentrations such as notches exist, or complex service loading conditions such as shear or multiaxial stresses are present. In this work notched fatigue behavior of AM metals under axial, torsion, and combined axial-torsion loadings are investigated and contrasted with their wrought counterparts, using two common AM metals, Ti-6Al-4V and 17-4 PH stainless steel. Different post fabrication heat treatments and surface roughness conditions were included. Part I of this two-part publication presents the fatigue test results and comparative analyses. In Part II, both crack initiation (i.e. critical plane-based method) and crack growth (i.e. fracture mechanics-based method) approaches to life predictions are used for predictive analysis and comparisons with the experimental results presented in part I.