strength improvement of nano-structured titanium processed by parallel tubular channel angular pressing

Parallel tubular channel angular pressing (ptcap), as a process of severe plastic deformation (spd), was employed for improving the strength of commercially pure titanium (grade 2). in the present research, the tubular samples of pure titanium were severely deformed by one and two passes of ptcap at the temperature of 450°c. it was found by the results of tensile tests that the yield and ultimate strengths increased by 24% and 29% after applying the second pass of ptcap, respectively. it was also showed that the vickers microhardness increased by 46%. moreover, the micrographs illustrated that the average grain size decreased from ∼21 μm in the unprocessed condition to ∼143 nm after applying two ptcap passes. therefore, applying the technique of ptcap was successful to produce the nano-structured titanium.