ECAP process improvement based on the design of rational inclined punch shapes for the acute-angled Segal 2θ-dies: CFD 2-D description of dead zone reduction

Abstract

Abstract. This article is focused on a 2-D fluid dynamics description of punch shape geometry improvement for Equal Channel Angular Extrusion (ECAE) or Equal Channel Angular Pressing (ECAP) of viscous incompressible continuum through acute-angled Segal 2θ -dies with 2θ < 90 • . It has been shown both experimentally with physical simulation and theoretically with computational fluid dynamics that for the best efficiency under the stated conditions, the geometric condition required is for the taper angle 2θ 0 of the inclined oblique punch to be equal to the 2θ angle between the inlet and outlet channels of the Segal 2θ -die. Experimentally and theoretically determined rational geometric condition for the ECAP punch shape is especially prominent and significant for ECAP through the acute angled Segal 2θ -dies. With the application of Navier-Stokes equations in curl transfer form it has been shown that for the stated conditions, the introduction of an oblique inclined 2θ 0 -punch results in dead zone area downsizing and macroscopic rotation reduction during ECAP of a viscous incompressible continuum. The derived results can be significant when applied to the improvement of ECAP processing of both metal and polymer materials through Segal 2θ -dies.

CFD 2D Description of Local Flow of Polymer Workpiece through a modified U-Shaped Die During Equal Channel Multiple Angular Extrusion

“…Minakowski (2014) has applied CFD-based techniques to a mathematical description of the flow of an aluminum workpiece during Equal Channel Angular Extrusion (ECAE) through a 2-turn angular die with internal and external radii in the channel intersection zones (3) . Perig et al, have solved the Navier-Stokes equations in a curl transfer form for the ECAE problem of workpiece viscous flow (5)(6)(7)(8) . Perig and Golodenko have applied CFD techniques to the numerical solution of the 2D problem for viscous material ECAE through a 2-turn multiple-angle S-shaped die with a movable inlet wall (6) .…”

“…Possible applications for ECMAE worked polymers are associated with aeronautical and chemical industry equipment production (1,(4)(5)(6)(7)(8) . The solution of the above mentioned technological problems is within the aims and scopes of research, conducted by Beloshenko et (5)(6)(7)(8)(9) , and Rejaeian and Aghaiae-Khafri (2014) (10) , and a number of other researchers (2,4,12,13) . The 2-turn, 3-turn, ..., and n-turn ECMAE dies with geometries of S -, U -, T -, X -, W -types could be classified as multiple angle dies (1,3,6,7) .…”

“…Computational Fluid Dynamics (CFD) techniques (3)(4)(5)(6)(7)(8)(9)(10)(11) are finding new and important industrial applications in the materials science related fields of Severe Plastic Deformation (SPD) (1,3,(5)(6)(7)(8)(9)(10) . Minakowski (2014) has applied CFD-based techniques to a mathematical description of the flow of an aluminum workpiece during Equal Channel Angular Extrusion (ECAE) through a 2-turn angular die with internal and external radii in the channel intersection zones (3) .…”

“…At the present time further development of SPD processing schemes during Equal Channel Multiple Angular Extrusion (ECMAE) is grounded on further increases in workpiece length and increases in accumulated shear deformations within the worked material volume by increasing the quantity of deformation zones for every pass of ECMAE (1,6,7) . The principal goal of ECMAE pressure working of polymer materials is focused on the introduction and accumulation of large plastic deformations in the polymer workpiece for further fragmentation of lamellar polymer structure with mechanical properties enhancement while retaining the optical transparency of processed polymer workpiece (1,(4)(5)(6)(7)(8) . Possible applications for ECMAE worked polymers are associated with aeronautical and chemical industry equipment production (1,(4)(5)(6)(7)(8) .…”

“…The principal goal of ECMAE pressure working of polymer materials is focused on the introduction and accumulation of large plastic deformations in the polymer workpiece for further fragmentation of lamellar polymer structure with mechanical properties enhancement while retaining the optical transparency of processed polymer workpiece (1,(4)(5)(6)(7)(8) . Possible applications for ECMAE worked polymers are associated with aeronautical and chemical industry equipment production (1,(4)(5)(6)(7)(8) . The solution of the above mentioned technological problems is within the aims and scopes of research, conducted by Beloshenko et (5)(6)(7)(8)(9) , and Rejaeian and Aghaiae-Khafri (2014) (10) , and a number of other researchers (2,4,12,13) .…”