Change in Structure of 60/40 Brass due to Cold-rolling and Annealing

The structure of 60/40 brass, consisting of α- and β-phase, is remarkably influenced by the condition of heat-treatment. However, almost no attention to control the structure for practical applications has been paid.The present work was carried out in order to know the changes in structure of commercial 60/40 brass due to the process of the 1st annealing, intermediate cold-rolling and 2nd annealing. The 1st annealing structures could be divided into four types by the shape and distribution of the phases, namely, martensitic, mixed, granular and elongated structures. Those structures are changed by the subsequent cold-rolling and 2nd annealing. The tendency of the structure change was ascertained in relation to the annealing temperature and cold-rolling reduction. Fine and uniform distribution of β-particles is obtainable, if the specimen was subjected to the 1st annealing at the temperature of the β-phase region, followed by the cold-rolling with high-reduction and the 2nd annealing at the two-phases region. The changes in proportion of the β-phase area and in hardness were also investigated.