The Effect of Annealing and Cryogenic Treatment on the Microstructure and Mechanical Properties of Ti-6Al-4V Alloy

In this work, a new method of annealing and cryogenic treatment was proposed to enhance the plasticity while maintaining the strength of the Ti-6Al-4V titanium alloy. The microstructure evolution and the variations of properties were also investigated. The experiment results show that the ultimate tensile strength is increased with the increase of the annealing temperature. After cryogenic treatment, the ultimate tensile strength of the samples first increased and then decreased with the extension of the cryogenic treatment time. The maximum ultimate tensile strength was obtained when the cryogenic treatment time was 12 h. The evolution of the elongation shows a reversed trend with the ultimate tensile strength. It can be observed from the microstructures that the volume fraction of the β phase gradually decreases with the extension of cryogenic treatment time. Comprehensively, the elongation of the samples after annealing and cryogenic treatment was significantly improved, with an average increase of 19.7% compared with the initial sample. The ultimate tensile strength of the samples decreased slightly, with an average decrease of about 0.046%.