EXPERIMENTAL AND COMPUTATIONAL SIMULATION OF PRODUCING ULTRA-FINE GRAIN STRUCTURE PROCESSED BY CGP

In this research the constrained groove pressing (CGP) process as a severe plastic deformation (SPD) method was applied on commercially pure aluminum plates. According to the principle of CGP, a material is subjected to repetitive shear deformation by utilizing asymmetrically grooved dies and flat dies which are constrained by a channel. Each complete groove pressing pass consists of four pressing operation steps. Considering the geometry of the die, in each complete pass, a large amount of strain is induced into the specimen. In the present research the effects of the deformation passes on the mechanical properties of the specimens were tested by micro hardness tests. In addition, in order to investigate the material flow along the grooves in the CGP process, the finite element simulations were carried for one of the process. Our approach involves computational simulation of the entire synthesis process for the optimization. Results show that the flow stress of the material and its hardness are affected by the number of passes. Post process of the finite element analysis showed that the real state of the CGP process is a combination of plane stress and plane strain conditions.