Heterogeneity and anisotropy in microstructure and mechanical properties of pure copper processed by equal channel angular pressing

Pure copper (99.98%wt) square bars (32x32 mm) were processed by equal channel angular pressing (ECAP) Microstructure evolution was characterized by microscopy. Room temperature mechanical properties were obtained by tensile and micro-hardness tests. With increasing number of ECAP passes and cold rolling reductions, the initial coarse grained structure in the as-received material was transformed gradually into an ultrafine grained microstructure with an average grain size of 0.2 similar to 0.3 mu m. Subsequent rolling resulted deformation twining in this ultrafine grained microstructure, which gives further strengthening in addition to the strengthening obtained by ECAP. Property anisotropy in three orthogonal directions of samples processed by ECAP was characterized by tensile testing.