Sensitivity analysis of the ECAE process via 2k experiments design

Abstract

In this work the theoretical solutions based upon the upper-bound theorem recently proposed by Pérez and Luri [Mech. Mater. 40 (2008) 617] for the equal channel angular extrusion process (ECAE) are analyzed by performing a 25 central composite factorial analysis. The uniaxial mechanical properties of commercial pure aluminium are considered by assuming isotropic nonlinear work-hardening combined to von Mises and Drucker isotropic yield criteria to predict the ECAE load and the effective plastic strain. From the proposed 25 factorial analysis, the main parameters affecting the ECAE pressure may be ranked as: (1) Friction factor, (2) die channels intersection angle, (3) outer and (4) inner die corners fillet radii and lastly, (5) plunger velocity. Alternatively, the effective plastic strain is mainly controlled by the die channels intersection angle and, in a less extent, by the outer and inner die corners fillet radii.

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

“…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.…”

“…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.…”

“…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). …”

“…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 . All previous research [1][2][3][4][5][6][7][8][9][10][12][13][14][15]19,22,24,27 has not fully addressed the complex geometry of the dead metal zone CEDF (Figures 3-6) nor the influence of complex dead zone geometry CEDF (Figures 3-6) on the character of metal flow during workpiece ECAE through a Segal 2θ-die applying a two-parameter UBM in the form of a two-parameter RBM with trial DVF. This insufficient analysis of energy-power parameters during ECAE with an introduction of the two-parameter UBM with DVF was the stimulus, which resulted in the research reported in the present article.…”

2D upper bound analysis of ECAE through 2θ-dies for a range of channel angles

“…The mechanics of Equal Channel Angular Extrusion (ECAE) attracts a lot of research efforts from different fields of theoretical, experimental and industrial science . Many contributions have been focused on the introduction of slip line fields 11,30,31 , Upper Bound Method (UBM) with continuous trial velocity fields [1][2][3][4][5][6][12][13][14][15][16][17][18][19]29,32 , Navier-Stokes equations 22,27,28 , fractal geometry techniques, discrete elements, FEM computational methods 2,12,14,15,20,[23][24][25] etc. The main computational approach in [3][4][5] has been grounded on the introduction of cylindrical coordinate systems with the center a symmetrical plastic deformation zone, deriving a kinematically admissible velocity field, computation of the only non-zero strain rate field component UBM for 1 DOF) with a trial DVF to the study of ECAE of an ideally plastic and strain-hardening metal workpiece through a die with channel intersection angle 2θ=90°, where the optimization parameter is the dead zone height 11 .…”