The finite element analysis of equal channel angular pressing (ECAP) considering the strain path dependence of the work hardening of metals

It is widely known that extreme grain refinement of metals can be attained through multiple passes of equal channel angular pressing (ECAP). Such processing can follow various strain paths, which correspond to different work hardening behaviors of the material being deformed. The available finite element analyses (FEA) of multiple pass ECAP do not consider this strain path effect, and employ a single stress–effective strain curve of the material for all passes. The present paper presents a FEA of a two pass ECAP processing of copper following route C. This processing route involves the shearing of the material in the same plane as in the first pass, but in a reversed shear direction. The experimental stress–strain curve of the material, considering this strain path change, was determined through reversed torsion at various strain levels associated with the strain heterogeneity in the material caused by the first ECAP pass. The consideration of the strain path effects changed the final strain distribution in the material and led to a lower punch force in the second pass, in comparison with the results from the analysis considering a single stress–strain curve for all passes.