Processing of commercial purity titanium by ECAP using a 90 degrees die at room temperature

摘要

Experiments were conducted to determine whether it is feasible to process commercial purity (CP) titanium (grade 1) by equal-channel angular pressing (ECAP) at room temperature with a die having an internal angle of 90°. Billets were successfully processed through up to 4 passes using a pressing speed of 3.5mm s~(-1). These results appear to represent the first successful processing of CP-Ti at room temperature using a 90° die. Processing by ECAP through 4 passes reduced the grain size from an initial value of ～25 μm in the unprocessed condition to an equiaxed grain size of ～150 nm. The results show that the hardness and tensile strength are increased significantly after ECAP and the material exhibits excellent elongations up to ～45% to 48% in tensile testing at room temperature. The success in processing CP-Ti at room temperature with a 90° die provides opportunities for incorporating additional processing steps in order to gain further grain refinement and strength enhancement.