Microstructure And Mechanical Properties Of Ultra-Fine Grained Copper Produced By Equal Channel Angular Pressing

With the developments of society, reqirements of structural materials are increasing, but resource is limited in earth. It is the only way to resolve the problem that researching and developing a new generation of structural materials that have higher strength and toughness. Ultra fine-grained (UFG) materials with sub micrometer-order grain size exhibit excellent mechanical properties compared with conventional materials.Equal channel angular pressing (ECAP) is a processing procedure in which a material is subjected to intense plastic straining but without the introduction of any change in the cross-sectional dimensions of the sample. It is a deformation route of serve pure shear. ECAP is successfully applied in the production of submicrometer grain materials (SGM).ECAP of copper was successfully carried out at room temperature, using 90° tooling with route C in which the sample is rotated 180° along its longitudinal axis in this study, obtaining a total equivalent true strain ~4. Equiaxed grain with clarity boundaries and average grain size of 0.2μm formed after four passes.Three-dimensional macro scale UFG pure copper was firstly produced by ECAP.The microstructure evolution of copper in ECAP was investigated by means of optical microscopy (OM) and transmission electron microscopy (TEM). The OM and TEM pictures exhibited considerable inhomogeneity in microstructure after each pass. Tensile specimens were sectioned by electrodischarge machining, and tested in the as-processed condiction. The ECAP-processed copper was anisotropic,with the strengthin tenslie the X, Y, Z directions.