Effect of shear state on fracture of refined grain pure copper

In recent decades, the industrial applications of refined grained pure copper and its alloys have been expanded. The properties such as high strength, high density, and low deformability make these alloys more attractive. Hence, investigating the fracture mechanism of refined grained copper is of great significance. In this study, the fracture analysis of copper is investigated using the equal channel angular pressing process. Experimental results on metal alloys demonstrate that stress states should be incorporated in the constitutive equations. Therefore, the fracture process is analyzed by focusing on its relationship with the Lode angle variable. To prepare the equal channel angular processed specimens, a die set is manufactured, and tensile strength tests are carried out on dog-bone and notched flat plate specimens up to fracture. In addition, the mean value of grain sizes of the copper specimens is evaluated. The results demonstrate that the grain refining process profoundly enhances the load-carrying capacity of copper specimens. Moreover, the dog-bone tensile tests clearly show that the peak value of the strain hardening in refined grained copper occurs up to two passes, and after two passes the strain hardening drops. Furthermore, the results reveal that the Lode anglel variable has a significant influence on the failure of the refined grained copper specimens.

Keywords:

Equal Channel Angular Pressing , Copper , Ductile fracture , Lode angle , Stress triaxiality