Research on the hot deformation behavior of Ti40 alloy using processing map

The deformation behavior of a Ti40 titanium alloy was investigated with compression tests at different temperatures and strain rates to evaluate the activation energy and to establish the constitutive equation, which reveals the dependence of the flow stress on strain, strain rate and deformation temperature. The tests were carried out in the temperature range between 900 and 1100°C and at strain rates between 0.01 and 10s^-1. Hot deformation activation energy of the Ti40 alloy was calculated to be about 372.96kJ/mol. In order to demonstrate the workability of Ti40 alloy further, the processing maps at strain of 0.5 and 0.6 were generated respectively based on the dynamic materials model. It is found that the dynamic recrystallization of Ti40 alloy occurs at the temperatures of 1050-1100°C and strain rates of 0.01-0.1s^-1, with peak efficiency of power dissipation of 64% occurring at about 1050°C and 0.01s^-1, indicating that this domain is optimum processing window for hot working. Flow instability domains were noticed at higher stain rate (≥1s^-1) and stain (≥0.6), which located at the upper part of the processing maps. The evidence of deformation in these domains has been identified by the microstructure observations of Ti40 titanium alloy.