Enhancement of grain refinement and mechanical properties of cross-roll rolled pure copper

Abstract

The aim of this work was to evaluate the effects of strain rate on the microstructural evolution of 5-mm-thick pure copper (99.99%) sheets subjected to conventional rolling (CR) and cross-roll rolling (CRR). The sheets were cold-rolled with a reduction ratio of 90% and then annealed at 400°C for 30 min to obtain the fully recrystallized microstructures. The resulting cold-rolled and annealed sheets had considerably finer grains than the initial sheets. In particular, the average grain size became smaller by CRR (6.5 μm) than by CR (9.8 μm). The mechanical properties of the sheets, i.e., Vickers microhardness and tensile strength, were more enhanced by CRR than by CR. The microstructural development in these processes was systematically discussed. © 2011 The Japan Institute of Metals.