The Effects of the Multi-pass Parallel Tubular Channel Angular Pressing on the Microstructure and Mechanical Properties of the Cu–Zn Tubes

In this study, ultra-fine grained (UFG) Cu–Zn tubes were produced by parallel tubular channel angular pressing (PTCAP) process and the effects of the number of passes on the microstructure, mechanical properties and fracture behavior were investigated. The results showed that the yield and the ultimate strengths of the processed UFG tube increased about four and two folds compared to the coarse grain counterparts due to grains refinement. The notable increase in the strength achieved after the first pass of the PTCAP process and further passes of the process only have a minor effect on the tube properties which may be due to the grain size saturation. However, the tube ductility reduced drastically after the PTCAP processing. Hardness of the PTCAP processed tube was increased compared to the annealed one according to Hall–Petch relationship which reports the hardness in terms of grain size. The strength, hardness and ductility were decreased after two passes PTCAP as a result of the formation of microvoids during the further straining through three passes. Microstructural investigations show a notable decrease in the grain size.