The chemical composition, organization and performance of brass
2020 05/08
Brass is Cu-zN alloy, and its structure is (a + 8) two-phase structure. Zn can dissolve into Cu to form a solid solution. Above 456 ℃, its solubility increases with the temperature drop; at 456 ℃, the solubility of Zn in a solid solution is greater at 39%; The solubility in solid solution decreases with decreasing temperature. Brass with Zn content <39%, through recrystallization annealing and slow cooling, can obtain a single solid solution structure, that is, single-phase brass (face-centered cubic lattice), excellent plasticity, both in hot and cold Very good formability; when the zinc content is 39% -46%, at 456-458 ℃ above is a + 8 two-phase structure, that is, two-phase brass, 8 phase is an electronic compound Cu-Zn-based solid solution, body center Cubic lattice; when the temperature drops to 456 ~ 458 ℃, an ordered transformation occurs, forming an ordered solid solution 13 'phase. 8-phase plastic has good plasticity, high strength and hardness, and 13 'phase is hard and brittle, and phase should be avoided during heat treatment. Therefore, dual-phase brass is suitable for hot working, that is, processing in a + B dual-phase state, but not suitable for cold working in a + I 3 state. Two-phase brass has high strength and good corrosion resistance, and is widely used in the manufacturing industry. However, when the zinc content is greater than 46%, the brass structure is all brittle I 3 phase, the plasticity is very poor, no practical value.