Observations and issues on mechanisms of grain refinement during ECAP process

The equal channel angular pressing route, defined by rotating schemes betwe en adjacent passes, significantly affects effectiveness of grain refinement . It is of interest to study the mechanisms of grain refinement. Previous w ork has considered the accumulative strain and the effects of shear strain plane in the interpretation of certain experimental observations. However, they are not sufficiently general, and contradict each other in some cases. In this paper, we analyze experimental results available in the literature , and investigate the fundamental mechanisms of grain refinement. We believ e that the interaction of shear plane with texture and crystal structure pl ays a primary role in grain refinement, while the accumulative strain plays a secondary role. Our model can explain the experimental results in the li terature very well. Issues on the grain refinement are discussed and furthe r research to solve these issues is suggested. (C) 2000 Elsevier Science S. A. All rights reserved.