The study of deformation behavior and microstructure evolution in forged pure tantalum

In this study, the deformation characteristics of as-forged pure tantalum were investigated using a Gleeble-3800 thermal simulation testing machine in the temperature range of room temperature to 350 °C and strain rates ranging from 0.1 to 10 s⁻¹, with a maximum deformation of 60 %. Results show that the deformation resistance increases with decreasing deformation temperature and increasing strain rate before reaching the peak stress. After reaching peak stress, deformation is dominated by dynamic recovery mechanisms. Based on the true stress-strain curves obtained from experiments, the deformation activation energy (Q) and stress exponent (n) of the material were calculated to be 5.133 kJ/mol and 3.1989, respectively. A constitutive equation describing the rheological behavior was established. Utilizing processing maps combined with post-deformation microstructures, optimal processing parameters were determined to be a deformation temperature of room temperature, a strain rate ranging from 3.5 to 10 s⁻¹, and a dissipation rate of 0.12. Under these optimal processing parameters, the material microstructure mainly consisted of dynamically recrystallized grains and deformed grains.