The effect of ECAP die shape on nano-structure of materials

A general flow line model is developed to investigate the deformation behavior of Cu and Al through Bc route of Equal Channel Angular Pressing process at curved and sharp dies. Considering the Taylor theory, the obtained strain and strain rate from the flow line model and also using a modified version of ETMB model, the evolutions of nano-structure in the processed Cu and Al are predicted. Comparison between the modeling results and experimental data is carried out and a reasonable agreement is achieved. The results show that the deformation in the sharp die occurs in a narrow zone with higher strain rate than that in the curved die. Also, the cell size of the processed Cu is smaller than that of the processed Al. Moreover, the cell size of the materials processed in the sharp die is finer than that in the curved die. It should be mentioned that in a specific range of strain the difference between the achieved cell sizes in the curved and sharp dies is small.