Fatigue Performance of Additively Manufactured Ti‐6Al‐4V: Impact of Different Kinds of Porosities, Surface, and Heat Treatments in Laser Powder Bed Fusion Productivity Parameters

In this article, the influence of lack of fusion (LoF) and keyhole (KH) porosity on static and cyclic mechanical properties in parts with as‐build and machined surfaces is analyzed using tensile testing and rotational bending fatigue testing. Three different printing parameters are selected to produce parts with intentional LoF and KH‐type defects and compared with fully dense parts. All samples are heat treated to relieve stress and eliminate the brittle martensite phase in Ti‐6Al‐4 V, and the effect of hot‐isostatic‐pressing (HIP) is also investigated to determine if it can restore cyclic mechanical properties of the parts with LoF and KH defects to the level of fully dense parts. The fatigue performance of as‐printed and machined parts is assessed using a rotating bending machine for cyclic loading. It is found that the surface roughness of the as‐built parts, even after HIP, resulted in a strong degradation of the fatigue limit compared to machined parts. Hot‐isostatic pressing of parts with either LoF or KH porosity resulted in similar or even higher fatigue performance than fully dense parts without HIP treatment.