Ductile fracture analysis of annealed and ECAPed pure copper

•Modified Xue fracture model suggested for copper based on the grain size parameter.•Hydrostatic pressure and Lode angle effects on ductile fracture were analyzed.•Tensile tests were performed on the cylindrical and doubly-grooved flat samples.•Stress triaxiality has a remarkable effect on ductile fracture of copper specimens.•Accuracy of model to predict annealed and ECAPed copper fracture was confirmed. In this paper, the ductile fracture of ultra-fine grained copper, purity 99.7%, processed by equal channel angular pressing (ECAP) is considered. To simulate the ductile fracture, a phenomenological ductile fracture model is developed by incorporating the effect of the grain size refinement during ECAP process. The implemented damage plasticity theory is assumed to be a function of the stress triaxiality, the Lode angle and the equivalent plastic strain. For verification and evaluation of the damage-plasticity model, a series of experimental tests are conducted on the ECAPed specimens. In order to manufacture the ECAPed specimens, the associated die set is designed and manufactured. The experimental tests are performed by pulling smooth and notched round bar as well as doubly grooved flat samples up to failure. Simultaneously, finite element simulations are performed to numerically simulate the fracture process. In the end, the numerical simulations are compared with the experimental ones. The results demonstrate the accuracy and efficiency of the suggested model in the prediction of the annealed and ECAPed copper fracture.