A New Configuration for Equal Channel Angular Extrusion Dies

Abstract

Equal channel angular extrusion or pressing (ECAE or ECAP) is a process used in order to impart severe plastic deformations to processed materials with the aim of improving their mechanical properties by reducing the grain size. The grain size reduction leads to mechanical properties improvement. In the present study, a new die configuration is proposed for the ECAE process. The advantage of this die geometry is that it allows us to obtain higher plastic strain in each ECAE passage than traditional ECAE dies. It is important to optimize the die geometry, as the main aim of the ECAE process is to impart severe plastic deformations to the processed materials. Consequently, the higher the deformation, the better the improvement on the mechanical properties of the processed materials. In order to determine how variations on geometry affect the plastic strain of the processed materials finite element modeling (FEM) is used. Both analytical and FEM methods will allow us to affirm that by using this new die configuration it is possible to achieve higher deformation values per ECAE passage.

Two-parameter Rigid Block Approach to Upper Bound Analysis of Equal Channel Angular Extrusion Through a Segal 2θ-die

“…Simple physical simulation experiments for analysis of ECAE flow through a non-rectangular Segal 2θ-die in Figures 3-6 show the complex structure of the dead metal zone CEDF (Figures 3-6), which has not been adequately addressed in previous known publications [1][2][3][4][5][6][7][8][9][10][12][13][14][15]19,22,24,27,28 . Moreover, the two-parameter rigid block approach to the two-parameter UBM of metal flow during ECAE with trial Discontinuous Velocity Field (DVF) introduction and accounting for the complex geometry of dead zone CEDF (Figures 3-6) for metal flow through a Segal 2θ-die has not been addressed in proper way in previous known publications [1][2][3][4][5][6][7][8][9][10][12][13][14][15]19,22,24,27 .…”

“…Tóth et al 28 have proposed a novel analytic approach to ECAE copper flow with the introduction of a flow line model. Milind 4,5 , Faraji et al 6 , Laptev et al 7 , Luri et al 8 , Luri & Luis 9 , Medeiros et al 10 , Narooei & Karimi Taheri [12][13][14] , Paydar et al 15 , Perig & Laptev 19 , Perig 22 , Reihanian et al 24 , Talebanpour & Ebrahimi 27 and others. Altan et al 3 have addressed the Upper Bound Method (UBM) with continuous trial velocity fields for description of metal ECAE motion through the Segal die.…”

“…The mechanics of metal flow during Equal Channel Angular Extrusion (ECAE) or Equal Channel Angular Pressing (ECAP) through the 2θ-dies of simple Segal geometry attracts a lot of research contributions from different fields of theoretical , experimental [28][29][30][31][32] and industrial 8,25,33 science. ECAE assumes one or several extrusion passes of a lubricated billet in a 2θ-die of Segal geometry with two intersecting channels of equal cross-section in Figures 1-2.…”

“…Berta et al 29 outline comparable experimental ECAE data on the structure of the treated metal blanks at various channel angles 2θ=90° and 2θ=120° [ 29] . It is necessary to note that many analytical computational approaches [1][2][3][4][5][6][8][9][10][12][13][14][15]24,27 initially determine the shape of the dead metal zone CED in an angular Segal 2θ-die (Figures 3-6). …”

“…Many contributions have been focused on the introduction of slip line fields 25,26 , Upper Bound Method (UBM) with continuous trial velocity fields [1][2][3][4][5][6][8][9][10][12][13][14][15]24,27 , kinematically admissible analytical approaches 11,28 , FEM computational techniques 2,8,9,11,17,18,23 , Navier-Stokes equations 16,20,21 etc. Segal 25,26 has grounded his analytic approach to ECAE metal flow with the introduction of slip line fields.…”