Flow softening and dynamic recrystallization behavior of BT9 titanium alloy: A study using process map development

In the present study, uniaxial compression tests were employed between 1000 and 1100 degrees C under the strain rates of 10(-3), 10(-2) and 10(-1) s(-1) to investigate the hot deformation behavior of BT9 titanium alloy. Work hardening behavior interpretation and analytical investigations including calculation of deformation activation energy, and developing process maps were used to establish a numerical correlation between microstructural evolution and the flow behavior of the alloy. The results showed that dynamic recrystallization takes place at severe condition (T = 1000 degrees C and (epsilon) over dot = 0.1 s(-1)), while dynamic recovery is the major microstructural mechanism at other condition. According to dynamic material model and Prasad's instability criterion, the maximum power dissipation of 52% and 46% occur at 1000 degrees C/0.1 s(-1) and 1150 degrees C/0.001 s(-1), respectively. Electron backscattered diffraction images and high resolution optical images also revealed that continuous dynamic recrystallization is the governing mechanism at these deformation conditions resulting in a significant grain refinement. Considering the calculated deformation activation energies, power efficiency domains and the microstructural observations, 1000 degrees C/ 0.1 s(-1) was determined as the optimum deformation condition. (C) 2016 Published by Elsevier B.V.