In this work, microstructural and mechanical properties of a cold rolled and annealed Cu-35Zn were investigated through the control of recovery and recrystallization kinetics. The main objective of this research was optimization of thermomechanical condition to achieve the maximum toughness by taking advantage of the bimodal microstructure as well as partial recrystallization concepts. For this purpose, two approaches were considered. In the first, the annealed brass samples were cold rolled to reductions of 60, 75 and 90% and were subsequently annealed in electrical furnace at temperatures from 300°C to 550°C. Results revealed that in the partial recrystallization temperature range, high strength due to non-recrystallized portion, whereas in the full recrystallization temperature range, high ductility due to recrystallized portion were achieved. In the second approach, the 90 % cold rolled samples were annealed in a salt bath furnace for 10 minutes. Due to higher heat transformation in the salt bath as compared to the electrical furnace, different mechanical properties were achieved. Selected samples were annealed in recovery and recrystallization temperatures, 250°C and 450°C, respectively. In order to investigate the competition between the above processes, samples were annealed at both temperatures for various holding times. The tensile test indicated that the ductility of samples that annealed in recovery temperature range were improved, mainly due to decreasing of dislocation density in the presence of mechanical twins. Also, strength and ductility were improved for samples annealed in recrystallization temperature range (for 1 and 5 minutes) because of partial recrystallization and for the samples annealed for 10 minutes due to the bimodal grain size distribution. On the other hand, in samples annealed in both the recovery and recrystallization temperature range, the recovery consumed low proportion of stored energy and by increasing the proportion of recovery than recrystallization, ultimate tensile strength and yield stress were increased due to the partial recrystallization, while the ductility was decreased. Comparison of the results in the two approaches indicated that the toughness of the samples processed in the salt bath furnace was about 220MJ/m 3 to 245MJ/m 3 , while for the ones annealed in the electrical furnace the maximum of toughness was 220MJ/m 3 . Keywords: Cu-35Zn brass , Cold rolling, Recovery and recrystallization, Microstructure, Strength and ductility
