The potential for scaling ECAP: effect of sample size on grain refinement and mechanical properties

The potential for scaling equal-channel angular pressing (ECAP) for use with large samples was investigated by conducting tests on an aluminum alloy using cylinders having diameters from 6-40 mm. The results show the refinement of the microstructure and the subsequent mechanical properties after pressing are independent of the initial size of the sample and, for the largest sample with a diameter of 40 mm, independent of the location within the sample at least to a distance of similar to 5 mm from the sample edge. By making direct measurements of the imposed load during ECAP, it is shown that the applied load is determined by the sample strength rather than frictional effects between the sample and the die walls. The results demonstrate the feasibility of scaling ECAP to large sizes for use in industrial applications. (C) 2001 Elsevier Science B.V. All rights reserved.