Fatigue-induced damage and crack growth of Cu processed by ECAP

Abstract

The fatigue-induced damage and crack growth behavior were studied on the ultrafine grained copper processed by equal channel angular pressing (ECAP). At high stresses, fatigue cracks were initiated at the shear bands (SBs) formed along the shear plane of the final ECAP. At low stresses, the grain coarsening occurred due to dynamic recrystallization. The slip bands were then formed inside these grains and subsequently served as an initiation sites for cracks. The direction of crack growth, either 45. or perpendicular to the loading axis, varied depending on the stress. The formation and growth mechanisms of fatigue crack are discussed based on the micrographic observation of surface damage.