The Effect of Strain Rate and Initial Grain Size on Deformation Behavior of OFHC Copper at Elevated Temperatures

Understanding of plastic deformation mechanisms and/or microstructural changes of metals and alloys at elevated temperatures makes possible to control their hot working behavior and final mechanical properties. The aim of the present work is to optimize the conditions to achieve maximum ductility in terms of initial grain size, process temperature and deformation rate. In this study, the OFHC (oxygen-free high conductivity) copper samples of different initial grain sizes (25, 50, 100 and 150 μm) were subjected to tensile tests at temperatures 300, 405, 500 and 700 °C (0.42 - 0.75 Tm) and cross-head speeds of 1, 2, 5, 10, 20 and 50 mm/min (strain rates of 5.6x10-4 - 2.8x10-2 s-1). Experimental results indicated that particular conditions (initial grain size of 50 µm; 700 °C of working temperature and 5.6x10-3 s-1 of strain rate) should be provided in terms of process temperature and deformation rate depending upon initial grain size for dynamic recrystallization and also maximum ductility.