Effect of Cold Rolling and Annealing on Microstructures and Hardness of Cu-32Zn-0.5Al-0.15Mn Alloy

Abstract The Brass commonly used in pipe industry, radiator, screw, and firearm’s cartridge case because their mechanical properties combination such as strength, ductility, corrosion resistance and good drawability. Deep drawing process are used to make cartridge case. In deep drawing process, the materials with high drawability are needed. In some case, drawability of metal can increased with adding alloying element, cold working, and heat treatment. In this research, the influence of addition 0.5 wt. % Al and 0.15 wt. % Mn on microstructure and hardness of Cu-32Zn alloy are investigated. The sample of Cu-32Zn-0.5Al-0.15Mn will be cold rolled with variation deformation levels of 20, 40 and 70%. Further, sample are annealed at temperature of 300, 400, 500 and 600 °C for 30 minutes. The result showed that the as-cast samples of Cu-32Zn-0.5Al-0.15Mn have the hardness of 72.4 VHN. Further, the as-homogenized showed the hardness of 70.66 VHN. Sample with 70 % deformation level showed the structure of shear band and have the highest hardness number of 236.6 VHN. On the other hand, sample with 20% deformation level and follow up by annealing process at 600 °C showed the lowest hardness of 135.94 VHN. The optimum hardness are reached on sample with 70 % deformation level and annealing temperature at 300 °C. This research conclude that the increase of deformation level follow up by the increase of sample hardness. Further, annealing process tend to decrease the sample hardness due to the grain growth.