Factors influencing the shearing patterns in equal-channel angular pressing

The shearing patterns are calculated for equal-channel angular pressing (ECAP) under three different conditions: (i) rotation of a sample around the X-axis when using a die angle of 90degrees. (ii) rotation around the X-axis when using a die angle of 120degrees and (iii) rotation around the Y- and Z-axes when using plate samples with a die angle of 90degrees. Separate sets of shearing patterns are constructed for the four standard processing routes: route A with no rotation of the sample between consecutive passes, routes B-A and B-C with rotations of 90degrees in alternate directions or the same direction between each pass, and route C with a rotation of 180degrees between passes. It is concluded that the development of a uniform microstructure of equiaxed grains, separated by high-angle grain boundaries, is favored using route B-C because (i) shearing occurs over large angular ranges on the three orthogonal planes within the sample, (ii) there is a regular and periodic restoration of an equiaxed structure during consecutive pressings and (iii) deformation occurs on each orthogonal plane. (C) 2002 Elsevier Science B.V. All rights reserved.