抄録
Ultrafine grained (UFG) copper was processed by equal channel angular pressing. After the processing, some samples were annealed at 160℃(3min). Materials with and without annealing are referred to UFG-A and UFG, respectively. Although the tensile strength of UFG-A was about 20% less than that of UFG, fatigue strength in the long-life field in excess of 10^7 cycles was higher in UFG-A than in UFG. The change in surface damage was monitored successively, showing the difference in formation behavior of surface damage between UFG and UFG-A. The surface hardness of both materials was severely decreased with stressing. The decreasing trend of hardness was closely related with the formation process of surface damage.
