Microstructure and tensile properties of additive manufactured Ti-6Al-4V with refined prior-β grain structure obtained by rapid heat treatment

Heat treatments tailored for additive manufactured Ti-6Al-4V can be used to attain desirable microstructures associated with superior mechanical properties. Rapid heat treatments, for example, can be used to recrystallise the microstructure of laser powder bed fusion (L-PBF) Ti-6Al-4V to obtain refined and quasi-equiaxed prior-β grains. In this study, we discuss the interplay between refined microstructures and the tensile properties of Ti-6Al-4V specimens. The influence of individual microstructural constituents on the tensile properties are examined in detail and directly compared to those found in specimens subject to conventional annealing treatments. It was found that rapid heat treatments into the β phase field can significantly refine the size of the prior-β grains found in as-built L-PBF Ti-6Al-4V, as well as alter the size and morphological arrangement of the resulting α laths. The proposed new heat treatments are clearly shown to have strengthened the alloy with no apparent detriment to the ductility of the material.