Inhomogeneity and anisotropy of microstructure and mechanical properties in severe plastic deformation processed pure copper
(School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China)
Abstract: Pure copper (99.95%) square bars (32 mm×32 mm) were subjected to equal channel angular pressings (ECAP) for 4 passes at room temperature, using 90？ die by route C. Optical microscopy (OM) was used to examine microstructure evolution. Small tensile specimens were sectioned by wire cutting and the mechanical properties were tested at room temperature and under the as-processed condition. The results show that significant inhomogeneity and anisotropy of microstructure and mechanical properties exist in the ECAPed material. The nearer the sample to the surface, the more inhomogeneous the microstructure is. In mechanical properties, inhomogeneity and anisotropy are ECAP pass dependent. With the higher accumulated strain resulted from high ECAP passes, the inhomogeneity and anisotropy decrease. The inhomogeneity and anisotropy can be considered to be resulted from the distributions of the strain inhomogeneity.
Key words: equal channel angular pressing; microstructure; mechanical property; inhomogeneity; anisotropy; pure copper