Microstructure and Mechanical Properties of CP-Ti Processed by 2 ECAP Passes Using a 90° Die at Room Temperature

Equal channel angular pressing (ECAP) deformation for commercial pure titanium (CP-Ti) was successfully conducted using a conventional die with an angle of 90 degrees between the channels at room temperature via route B, in which the billet was rotated 90 degrees along its longitudinal axis between adjacent passes. Each billet was processed for two passes using a ram speed of 26mms(-1). The microstructures and mechanical properties of these CP-Ti billets with an initial grain size of similar to 23 mu m processed by ECAP were investigated. Experiment results show thin parallel shear bands with a width of 0.3 similar to 0.4 mu m are generated after one ECAP pass, which are composed of large number of dislocation cell blocks. After the two ECAP passes, some various directional bands are generated and the equiaxed and smaller-than-average CBs in local areas begin to appear. In addition, the ultimate strength and microhardness are significantly enhanced to similar to 725MPa and similar to 2283MPa, respectively. Meanwhile good elongation of 18.0% to failure is still remained.