Cyclic plastic behavior of additively manufactured Ti-6Al-4V under uniaxial and multiaxial non-proportional loading

•Four varieties of additively manufactured Ti-6Al-4V have been tested under strain controlled uniaxial and multiaxial non-proportional low cycle fatigue to investigate the cyclic plastic deformation. Influence of layer orientation and heat-treatment on cyclic plastic behavior, softening behavior and fatigue life is discussed.•Failure life was found to be similar regardless of heat treatment or layer orientation for both uniaxial and non-proportional loading.•Initial rapid softening occurred for the majority of the samples which was not found in the wrought material. A correlation between final crack propagation and layer orientation could be observed from the hardening softening curves.•Additional hardening occurring in heat-treated samples was observed. This behavior was not observed in wrought specimens. Cyclic plastic behavior of additively manufactured Ti-6Al-4V titanium alloy was experimentally investigated under non-proportional multiaxial cyclic loading. Four cylindrical hollow specimen types were fabricated using laser powder bed fusion (L-PBF). The typology of each specimen was defined by the orientation of the layers and application of a stress-relief heat treatment post production. Then, the specimens’ microstructures were analyzed. Stress–strain cyclic testing in the specimens’ plastic region resulted in near-equivalent curves for each fabricated specimen type. Fatigue tests evidenced that the fatigue life was similar regardless of heat-treatment and layer orientation. Hysteresis loops showed a higher energy absorption for the heat-treated components. Drastic softening has been detected in the majority of the tests and cracks initiating from internal voids, internal defects and surface could be observed.