Optimum groove pressing die design to achieve desirable severely plastic deformed sheets

In this paper, considering the problems of common finite element (FE) codes that consider simple constitutive equations, a developed FE code that considers a new constitutive model is used to simulate the behavior of copper sheets under severe plastic deformation (SPD). The new proposed constitutive model, that considers dislocation densities in cell interiors and cell walls of material as true internal state variables, can investigate all stages of flow stress evolution of material during large plastic deformations and also can explain the effects of strain rate magnitude on the mechanical response of material, during room temperature SPD. The proposed FE analysis is used to investigate the effects of die design on the property of SPDed sheets by groove pressing (GP) processes. To do so, the GP processes through existent designations of dies are simulated and a good agreement between the modeling results and experimental data is obtained. In addition, a new die design is proposed that can eliminate the problems of the existent designations of dies and can produce the sheets with higher strength and more uniform hardness.