Structural characterization and detecting processes of defects in leaded brass alloy used for gas valves production

Abstract

The structure of leaded brass alloy used for gas valves production is studied. Some scientific knowledge and facts about this subject are introduced. The melting and casting of leaded brass billets, hot extrusion with cold drawing of rods and hot forging of gas valves are performed. Some changes in production parameters are performed and 30% of pure materials added to improve the final products and minimize the defects. The structure of alloy is studied using optical and SEM/EDS devices for inspections. Radiographic and ultrasonic tests are used to detect the cracks and other defects in final products. The results indicated that the structures, phase distribution and the quality of leaded brass alloys differ slightly during casting, extrusion and hot forging processes. Also, most of samples consist of α and β phases with lead particles distributed on the grain boundaries or inside these phases. Very small crack is appeared in one sample of the forged gas valve, while the other valves are free. Improving the production parameters and also using of pure materials in charge elements are contributed by result improvement. SEM/EDS investigation results confirm the microstructure results of optical microscope for sample element distribution. Keywords: Leaded brass, Defects, Microstructure, Investigation, SEM