Microstructure, Hardness, and Corrosion Resistant Characteristics of Cu-28Zn-1Sn Alloy Under Cold Rolling and Annealing Treatments Imam Basori, Dimas Hadi Prahasto, Ferry Budhi Susetyo
Department of Mechanical Engineering, Universitas Negeri Jakarta, Indonesia
Abstract
This study aims to investigate the effects of cold rolling and annealing processes on the microstructure, hardness, and corrosion resistance of Cu-28Zn-1Sn brass alloy. The brass specimens were subjected to cold rolling with thickness reductions of 20, 40, and 70 percent, followed by annealing treatments at temperatures of 300 C, 400 C, 500 C, and 600 C for 30 minutes. Microstructural analysis was conducted using optical microscopy, hardness was evaluated using the Vickers hardness method, and corrosion resistance was assessed through a weight loss test in an H₂-SO₄- corrosive medium. The results indicate that cold rolling increased the hardness of the alloy due to strain hardening, which was accompanied by improved corrosion resistance. The hardness values increased with increasing plastic deformation during cold rolling, reaching 185.4 VHN, 247.2 VHN, and 254.8 VHN for 20, 40, and 70 percent reductions, respectively. Corrosion resistance also improved with increasing deformation, as indicated by the reduction in corrosion rate from 0.119 mmpy at 20 percent reduction to 0.112 mmpy at 40 percent reduction and 0.077 mmpy at 70 percent reduction. In contrast, the annealing treatment significantly reduced hardness at all deformation levels, particularly at 70 percent deformation, where the hardness decreased from 243.3 VHN at 300 C to 89.9 VHN at 600 C. Annealing also reduced the corrosion rate, with the lowest corrosion rate observed at 600 C annealing and the highest at 300 C for all deformation levels. The annealing process was proven to restore corrosion resistance and improve the microstructure through recrystallization mechanisms.
