Özet:

Two types of leaded brass alloys (CuZn40Pb2 and CuZn39Pb3) as extruded rods, which use to produce pressurized gas valves were produced by a vertical semi-continuous casting, hot extrusion, cold drawing, hot forging and machining processes. The effect of lead element on machinability of these alloys was explained. The common defects of the mentioned leaded brass rods, the causes and its remedies were explained. Many defects during productions stages of leaded brass rods were occurred, such as cavities, non-metallic contaminates, lead clustering, surface cracks and zinc segregation into foundry process. In addition, surface crack, hot tearing and back defect through hot extrusion, chevron and chemical composition cracks into cold drawing with hot bursts and lap during hot forging were appeared. The machining process and in-service processes were also involved some other defects. All these defects were occurred due to no care during manufacturing process stages and using improper technological parameters and bad casting product design. To remedying the above-mentioned defects, the proper and improving technological parameters with optimal product design must be used. The current technical review of all types of defects in leaded brass alloys, have been found that, these defects can be appear and increasing in sub-sequence applications and in-service stages.

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