Mechanism of size effects in microcylindrical compression of pure copper considering grain orientation distribution

Abstract

In microscale deformation, the magnitudes of specimen and grain sizes are usually identical, and size-dependent phenomena of deformation behavior occur, namely, size effects. In this study, size effects in microcylindrical compression were investigated experimentally. It was found that, with the increase of grain size and decrease of specimen size, flow stress decreases and inhomogeneous material flow increases. These size effects tend to be more distinct with miniaturization. Thereafter, a modified model considering orientation distribution of surface grains and continuity between surface grains and inner grains is developed to model size effects in microforming. Through finite element simulation, the effects of specimen size, grain size, and orientation of surface grains on the flow stress and inhomogeneous deformation were analyzed. There is a good agreement between experimental and simulation results. The deformation behavior in micro compression of pure copper has been investigated by a modified surface model considering orientation distribution of surface grains and continuity between surface grains and inner grains.