ANALYSIS ON THE CONSTITUTIVE RELATIONSHIP OF TC18 TITANIUM ALLOY BASED ON THE SOFTENING MECHANISM

Abstract

The true stresstrue strain curves have been attained through the isothermal compression experiment of TC18 titanium alloy. The influence of deformation parameters on the shape of stress-strain curves and peak stress has been analyzed through the working-hardening and dynamic softening effects. The true stress-true strain curves show the similar characteristics under different deformation conditions. However, the peak stress is sensitive to the changes of deformation parameters. The type of dynamic softening mechanisms in hot deformation under certain conditions can be obtained through Poliak-Jonas criterion. The dynamic recrystallization process tends to take place during the deformation with lower strain rates. And the choice of the dynamic softening mechanisms is not sensitive to deformation temperatures. The suitable constitutive models under different softening mechanisms have been constructed based on the traditional Arrhenius equations. With the identification of the dynamic softening mechanisms in hot deformation of TC18 alloy with different conditions, the response of true stress, at strain of 0.7, to the deformation temperatures and strain rates can be described through the proposed models. And the sensitivity coefficient of strain rates and deformation activation energy, of the process with the dynamic recrystallization as the major softening mechanism, are much larger than the ones of process with dynamic recovery.