Hot Deformation Behavior of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe Alloy in α + β Field

The deformation behavior of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe high strength beta titanium alloy is systematically investigated by isothermal compression in alpha + beta field with the deformation temperatures ranging from 1003 K to 1078 K, the strain rates ranging from 0.001 s(-1) to 1 s(-1) and the height reduction is around 50%. Essentially, the flow stress-strain curve of isothermal compression in alpha + beta field exhibits a flow softening feature when the strain rate is higher than 0.1 s(-1) as while it exhibits a steady-state feature as the strain rate is lower than 0.1 s(-1). The peak stress increases with a decrease in deformation temperature and the increase of strain rate. The activation energy for deformation in alpha + beta field was calculated and the average activation energy of 271.1 kJ/mol. The microstructure observation reveals that the isothermal deformation in the alpha + beta field of the alloy is mainly controlled by the dynamic recovery mechanism accompanied with the secondary dynamic recrystallizitation of beta phase. The alpha phase shows an obvious pinning effect for the movement of dislocations. During deformation, the alpha phase was elongated and fragmented.