Oxygen-free copper was processed by equal channel angular pressing with different numbers of ECAP process cycles, NP. Tensile tests were performed to clarify the effect of NP on tensile strength and elongation. Tensile strength was increased with an increase in NP, but it tended to saturate after NP =4. Conversely, elongation was dramatically decreased by first pressing followed by salutation trend up to NP=3. However, it tended to increase after NP=4. In addition to this, specimens processed with NP=4 and 8 were fatigued at three constant stress amplitudes ; σa240, 120 and 80 MPa. The change in surface morphologies during fatigue process was monitored by OM and SEM. At the same time, change in surface hardness during fatigue was measured. Significant decrease in surface hardness due to cyclic stresses was measured. To discuss the physical basis of particular tensile properties and fatigue characteristics, TEM observation and measurement of heat-flow values by DSC have been carried out.
