Effect of acute tool-angles on equal channel angular extrusion/pressing

Acute tool-angles in equal channel angular extrusion (ECAE) can increase the strain induced in the material within minimum number of passes. Such increased strains can yield ultrafine grains and high fraction of high angle grain boundaries, which enhance mechanical and superplastic properties. However, the deformation and punch pressure requirements will be more stringent demanding detailed investigation. In this study, finite element simulations of ECAE were carried with Abaqus/Explicit for die/channel angles of 60° and 75° in comparison to 90°. Outer corner angle of 10° was considered for all simulations. Factual phenomena like strain hardening of material and friction were considered for the simulations. Deformation was found to take place in three steps for acute channel angles ϕ = 60° and 75°, two steps for that of 90°. Corner gap, which is often the major drawback in the case of 90° channel angle, was not a factor for the acute channel angles. Punch pressure requirements were also found to be high with acute tool-angles.