Slip line solutions, deformation mode and loading history during equal channel angular extrusion

Equal channel angular extrusion (ECAE) is analyzed by the slip line method. Full solutions are considered in function of contact friction, backpressure and tool design. It is shown that variations in boundary conditions have a moderate effect on equivalent strains but the strain distribution depends noticeably on friction uniformity and the channel geometry. The characteristic deformation mode corresponds to single shear or to sequence of shears along slip lines. The processing mechanics plays an especially important role in the loading history of material elements. During one pass, monotonic loading is realized only in the cases of zero and maximum friction. For intermediate friction, the deformation history is composed by cross loading into three divergent directions. Multi pass ECAE via different routes is linked with a grain refinement mechanism under severe plastic deformation.