The Effect of Annealing Temperature on the High Temperature Deformation Behavior of Ti-5Al-4.2V-0.8 Mo-2Fe α/β Titanium Alloy

This paper aims to analyze the effect of annealing temperature on the microstructural changes and the following deformation behavior of Ti-5Al-4.2V-0.8Mo-2Fe α/β titanium alloy at high temperatures. For this purpose, the hot rolled specimens were mill annealed at 700, 750, and 800 °C for 1 hour. The deformation behavior of the milled annealed alloy was assessed using the hot tensile test at the temperature of 750 °C and the strain rate of 0.005 sec-1. It was found that, by increasing the mill annealing temperature, the layered microstructure changed to the equiaxed one due to static globularization. After the tensile test, the stress-strain curves showed that by decreasing the annealing temperature from 800 to 700 °C, the peak stress decreased and the elongation increased from 362% to 474%. Moreover, the apparent feature of flow curves suggested yield point phenomena as a result of dynamic strain aging. The maximum elongation of 474% was obtained after mill annealing at 700 °C a finding which is correlated with the promoted fine globular α phase with the grain size of 4.5 µm and the 44.5% content of the β phase due to the dynamic globularization.