CP-Ti Processed for Multiple Passes by ECAP at Room Temperature

A series of experiments were conducted to evaluate the feasibility that commercially pure titanium (CP-Ti) was pressed for multiple passes by equal channel angular pressing (ECAP) at room temperature. Samples of CP-Ti were processed at room temperature using the dies with channel angles of 90 degrees and 120 degrees, respectively. First, each billet was processed 4 passes by ECAP using a die with an angle of 120 degrees and a ram speed of 0.5mm s(-1). And in order to eliminate residual stress, immediate annealing at 473 K for an hour was conducted between two adjacent passes. Second, CP-Ti was successfully processed by ECAP for up to 8 passes using the same die and a ram speed of 2 mm s(-1) by controlling the flow of metal. Finally, CP-Ti was successfully achieved using a conventional die with an angle of 90 between the channels at room temperature. Each billet was processed for two passes with a ram speed of 26 mm s(-1). These experiments show that CP-Ti may be processed by ECAP at room temperature and special attention was paid on improvements in the yield stress, ultimate strength and micro-hardness of ECAPed-Ti that are slightly higher than the improvements attained after pressing at elevated temperatures.