On the Hybrid Modeling of Phenomenological Damage Evolution in Low Carbon Steels During Equal Channel Angular Extrusion Process

Low carbon steel is widely used in industry due to its excellent elastoplastic behavior with the mechanism of damage accumulation during severe plastic deformation processes which lead to increase strength resistance. In this study, the strain locus of the failure is predicted based on the stress triaxiality and Lode angle-dependent damage model by considering damage evolution during the process. Therefore, by performing various tests for several stress states and modeling the load paths related to damage accumulations, the coefficients of the modified Mohr–Coulomb damage model and Johnson–Cook are determined. According to results achieved among the test with good accuracy, the predictor locus of the failure strain is illustrated. Then, using the determined coefficients, the steel damage evolution is investigated during the process of Equal Channel Angular Extrusion (ECAE). It is shown that the damage accumulation during the ECAE process in a die with respectively internal and external angles of 90 and 30 degrees grows from the region closer to the internal angle as reaches a maximum value in central regions. Also, the amount of damage in vicinity of the outer angle is extremely reduced. According to experiments, the steel does resist fracture events after the ECAE process.