Influence of ultrafine-grained structure produced by equal-channel angular pressing on the dynamic response of pure copper

Metallic materials with a nanocrystalline or ultrafine-grained (UFG) structure can exhibit increased strength, albeit with reduced ductility. The behaviour of such materials under high-speed and impact loads has been insufficiently explored. This work presents experimental results on the dynamic response of UFG pure copper (99.95%) processed by equal-channel angular pressing (ECAP) in comparison with its initial coarse-grained (CG) structure. The yield strength in the case of compression tests of cylindrical samples and the energy consumed for deformation and fracture in the case of a three-point bending of a beam with a V-notch are considered. The UFG copper has higher yield strength in compression tests, but its sensitivity to the loading rate is significantly less than that of the CG initial material and depends on the number of ECAP passes. The UFG material shows higher impact toughness KCV and energy consumption for the entire process of deformation and fracture under impact three-point bending.