Microstructure of TC21 Titanium Alloy after Superplastic Deformation and Heat Treatment

Abstract

The isothermal constant strain rate tensile tests of the TC21 titanium alloy were conducted by SSAN-CMT4104 electronic tensile testing machine at different temperature. After superplastic deformation, the alloy was treated with double annealing heat treatment, and microstructure of the alloy was analyzed. The results show that dynamically recrystallization occurs during the superplastic tensile deformation. The primary α-grains aggregated and merged to form new crystal grains with irregular grain boundaries. The amount and morphology of primary α phase change gradually with the increasing of temperature. The alloy has duplex microstructure composed of primary α phase and different forms of β-transformed structure after superplastic deformation and double annealing. At deformation temperature of 930°C, the basket weave structure with equiaxed α phase appears.