Microstructural Investigation of CuZn40Pb2 Brass: Effects of the Isothermal Heat Treatment

Hot forming process involves the plastic deformation of metal alloys such as steel and copper to produce pieces. The influence of holding time and isothermal temperature on the microstructure and the hardness of CuZn40Pb2 brass were performed through quenching tests using a thermomechanical simulator Gleeble-3500 that allows water cooling without moving the specimen. The tests were carried out at different temperatures (650 ℃, 750 ℃ and 850 ℃) and holding times (30 s, 60 s and 90 s). Microstructure analysis using Electron BackScatter Diffraction and grain size measures were performed, as well as Vickers hardness tests in the transverse and longitudinal directions. The results showed that the hardness increases with increasing the temperature and the holding time. Up to a holding time of 60 s, the hardness was almost constant in both transverse and longitudinal directions. Therefore, in terms of the microstructure evolution, the average grain size of the non-treated specimen was 27 µm, while the isothermal temperature and the holding time significantly affected the average grain size of the treated specimen. Grain growth was obtained when the holding time and/or the isothermal temperature increase. At a holding time of 60s, the average grain sizes increased from 31 µm to 55 µm with temperatures of 650 ℃ and 850 ℃, respectively.