Exceptional fatigue life and ductility of new liquid healing hot isostatic pressing especially tailored for additive manufactured aluminum alloys

Abstract

Porosity and hot cracking still hinder the introduction of new additive manufactured alloys on the market, which requires high reliability. Hot Isostatic Pressing (HIP) is thus commonly applied to close these defects. Although HIP showed promising results as post-treatment on steel and titanium alloys, it is detrimental on aluminum alloys. Liquid assisted healing is thus applied during HIP to not only compress the pores, leading to stress concentration defects but to completely heal them. An Al-Mg alloy was manufactured as a proof-of-concept and X-ray nano-holo-tomography highlighted the healing of almost all the defects, even a 80 µm diameter pore, during liquid assisted HIP. This leads to the substantial increase of the fracture strain by a factor 3 without strength loss and an exceptional increase in fatigue life up to a factor 100. This healing HIP treatment is promising for post-treatment of other Al alloys but also as in-service healing treatment.