investigation into the effect of Heat Treatment Base Metal on the microstructure of Friction Stir Processed Brass

Copper has been widely applied in many areas for its high electrical and thermal conductivities, favorable combinations of strength and ductility, and excellent resistance to corrosion. However, it’s difficult to join commercial pure copper by conventional fusion welding processes due to the influence of oxygen, hydrogen, impurity and high thermal conductivity. To overcome these difficulties, in this study, we used a friction stir processing procedure and annealed and quenched raw materials. Grain sizes in base metal and stir zone were calculated by using the Digimaizer and also the phase percent was calculated by Clemex. Results show that there was no zinc evaporation happened and due to the finer microstructure of 63BA, the higher microhardness was obtained. Due to the presence of zinc element as an alloying element, α phase in single phase and α and β phase in dual phases matrix, and also the hardness of α phase in stir zones, there are many preferred places to nucleate which formed during plastic deformation and obtained fine grain microstructure. The stir zone has the dynamic crystallized grains including two phases microstructure, α, and β where the amount of α phase is 58 % and β phase is 42 % which with considering the base metal structure, the amount of β is reduced and the amount of α phase is increased.