Comparative Study of Continuous and Batch Heat Treatment in the Manufacturing Process of Cu-30Zn Brass Cup

Cu-30Zn brass cups are used as raw materials for small-caliber ammunition casings, which must meet strict standards. One crucial process to achieve the desired characteristics is heat treatment. This study compares two heat treatment methods, continuous and batch, at temperatures of 600 °C, 635 °C, and 670 °C for 32 minutes. After the heat treatment process, the samples were cooled to room temperature and washed. Characterization included measuring eccentricity, observing microstructure using an optical microscope, and testing hardness using the Brinell method. Microstructural observations showed that samples treated in a continuous furnace tended to have smaller and more uniform grain sizes compared to batch heat-treated samples. The grain size after continuous heat treatment at 600 °C, 635 °C, and 670 °C was 0.067 mm, 0.085 mm, and 0.097 mm, respectively, while for batch treatment, they were 0.107 mm, 0.123 mm, and 0.143 mm. Hardness increased as grain size decreased, with continuous heat treatment showing 60 BHN, 59 BHN, and 57 BHN. Based on the hardness, microstructure, and eccentricity data, continuous heat treatment at 600 °C to 650 °C for 32 to 45 minutes is recommended, while batch heat treatment does not meet standard specifications.