Cyclic deformation behavior of ultra-fine grained copper processed by accumulative roll-bonding

The cyclic deformation behavior of ultra fine grained copper after 7 cycles of accumulative roll bonding (ARB) have been systematically investigated under both load controlled and total strain controlled tests. The composite microstructure found in the as-ARBed samples has lead to unique behavior of this material. Cyclic softening as well as cyclic creep has been observed in asymmetrical cyclic tests. Grain coarsening was observed under both load controlled and total strain controlled tests. Cyclic softening behavior has been attributed to the grain coarsening phenomenon in the material. Surface damage due to shear banding was found to be the major failure mechanism. In addition, the coarsened grains have been detected to locate near and along the pre existent shear bands. The coarse grains already formed during the ARB-processing were shown to accommodate cyclic plastic strain by the formation of slip bands in their interior.