The influence of finish machining depth and hot isostatic pressing on defect distribution and fatigue behaviour of selective electron beam melted Ti-6Al-4V

Abstract

Porosity related defects within metal additive manufactured components has made it challenging to certify their use in fatigue critical applications. In this study, the fatigue behaviour of selective electron beam melted (SEBM) Ti-6Al-4V specimens following hot isostatic pressing (HIP’ing) and finish machining has been investigated. Employing a sufficient material removal depth during machining was shown to significantly improve fatigue performance. This was attributed to be a direct result of removing material rich in lack-of-fusion defects, concentrated in the sub-surface. HIP’ing was shown to enhance fatigue performance to a lesser degree, as the treatment was only effective at reducing gas porosity.