Effect of Heat Treatment Procedure on Mechanical Properties of Ti-15V-3Al-3Sn-3Cr Metastable β Titanium Alloy

In this study, the effects of various heat treatment procedures on the mechanical properties of the Ti-15V-3Al-3Sn-3Cr metastable β titanium alloy were investigated. Single-step and duplex aging treatments were applied to the alloy at low and high aging temperatures. Duplex aging treatments were carried out by selecting two different pre-aging times and temperatures: 10 h at 300 °C and 24 h at 250 °C. Thus, the effects of pre-aging on the mechanical properties of the alloy were examined. Optimum tensile properties were obtained in the duplex-aged samples, which was aged at 550 °C for 20 h after being pre-aged at 250 °C for 24 h. While fine, high volume fraction and uniformly dispersed α phases increased the tensile strength and % elongation of the alloy in the aging treatment, the fatigue crack propagation rate also increased. Also, it was observed that the threshold stress intensity factor range (ΔK_th) increased with the aging treatment. While the lowest ΔK_th value was obtained at the solution-treated sample, the highest ΔK_th value was obtained in the sample to which duplex aging treatment was applied depending on precipitation of fine and high volume fraction of α phases.