Fatigue damage generation in ECAPed oxygen free copper

Abstract

In order to understand the fatigue damage generation of ultra-fine grained copper, rotating bending fatigue tests were carried out. After the 4 and 8 pass of ECAP (equal channel angular pressing) with B-c route, grains with about 300 mm diameter were formed. The damage profile of fatigued surfaces between annealed pure copper and ECAPed one had substantial difference in morphology was observed. To clarify the formation process of surface damage, morphological change in surface caused by cyclic stresses was monitored successively by using optical microscope. It was found that the surface damages for the ECAPed copper propagated along the projected direction of shear plane in ECAP process. (C) 2008 Elsevier B.V. All rights reserved.