Mechanical Properties and Thermal Stability of CP-Ti Processed by ECAP at Intermediate Temperature

ECAP at intermediate temperature with rout BC was successfully processed to six passes in commercial pure titanium(CP-Ti) using a die with the internal angle Φ of 90° and outer curvature angle Ψ of 20°.The equivalent strain is about 6.3.At the end of the trial after intermediate temperature ECAP,the cold-rolling deformation of the samples was carried out at the reduction of 55%.Meanwhile,the deformation specimens' microstructure performance and the effect of passes and annealing temperature on the microstructure and mechanical properties were investigated.Moreover,the ultimate tensile strength(UTS) of CP-Ti is over 760.5 MPa and its elongation is up to 40%.When the annealing temperature is below 400 ℃,the microhardness slightly decreases,but its microstructure changes little.When the annealing temperature is over 400 ℃,because the dislocation density decreases through recovery and causes re-crystallization,and the microhardness decreases markedly.