Optimal tensile properties of laser powder bed fusion hereditary basket-weave microstructure in additive manufactured Ti6Al4V

Abstract

Post-heat treatments applied to laser powder bed fusion ( L -PBF) additive manufactured (AM) Ti6Al4V components aim to achieve good strength-ductility matching through tailoring microstructures, including microstructural features that span across length scales, such as prior β phase grains, laths and precipitates. The effects of initial prior β microstructure and subsequent solution treatment and aging (STA) on mechanical properties have been investigated. In all cases, the increase of solution temperature and aging treatment improve the strength due to solution-strengthening and precipitation-strengthening. It is confirmed that the L -PBF hereditary basket-weave microstructure possesses better tensile properties than other microstructures, with an ultimate tensile strength of 1185 ± 6 MPa and an elongation of 15.3 ± 0.3%. The optimal tensile properties stem from the fine structured primary α and transformed β phases in the retained L -PBF prior β grains, which are both beneficial to improving the work-hardening capacity, as well as enhancing the resistance to crack initiation and propagation. This finding can guide the optimization of mechanical properties for the L -PBF additive manufactured Ti6Al4V components. • Multi-heat treatments in single-phase region and dual-phase region are performed. • Retained L -PBF characteristics possess optimal tensile properties. • Fine structures contribute to good performance in the work hardening. • Fine structures enhance the resistance to crack initiation and propagation.