A comparison of warm and combined warm and low‐temperature processing routes for the equal‐channel angular pressing of pure titanium

Two different processing routes are used to investigate the microstructure and strength of commercial purity (CP) titanium of grade 4 processed by equal‐channel angular pressing (ECAP). In the combined temperature (CT) route, the specimens are pressed at 723 K in the first pass and at 373 K in the second pass, but in the warm temperature (WT) route, the specimens are pressed through two passes at 723 K. Both routes lead to an inhomogeneous microstructure with an average grain size of ≈1.5 and ≈1.7 μm after the CT and WT routes, respectively. Both routes give improved strengthening and higher hardness, but the CT route with a lower temperature step gives the highest ultimate tensile strength of ≈790 MPa. The inclusion of a lower temperature processing step may be important for optimizing the strength of CP Ti for the use in medical implants