Analysis of equal channel angular extrusion by upper bound method and rigid blocks model

Abstract

In present paper the Equal Channel Angular Extrusion (ECAE) through a rectangular die was firstly physically simulated using plasticine and then theoretically analyzed by upper bound method. Physical simulation was used to identify the deformation zone and as a background for the following theoretical ECAE analysis by rigid block model. The plane strain deformation mode and ideal plasticity of an extruded material were assumed. The dependencies of ECAE pressure, accumulated shear and dimension of a "dead zone" upon friction factor were analytically determined. The rise in ECAE pressure, accumulated shear and size of a "dead zone" with the increase in friction was predicted. The obtained results were compared with the slip line based solution and a good agreement between them was found. Finally the results of upper bound analysis were discussed together with the results of experimental investigations and finite element analysis of ECAE mechanics published elsewhere.

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

“…Physical simulation techniques using plasticine workpiece models are often used in material forming practice (Chijiwa et al, 1981;Han et al, 2008;Laptev et al, 2014;Perig et al, 2010Perig et al, , 2013aPerig et al, , b, 2015Perig and Laptev, 2014;Perig and Golodenko, 2014a, b;Perig, 2014;Sofuoglu and Rasty, 2000;Wu and Baker, 1997). In order to estimate the character of viscous flow during ECAP through a 2θ acute-angled angular die of Segal geometry ABC-abc under the action of a classical rectangular punch and a novel modified 2θ 0 -inclined or 2θ 0 -beveled punch shapes we have utilized physical simulation techniques in Figs The main experimental visualization technique in Figs.…”

“…For the last 20 years a number of research efforts in materials science related fields have been focused on wider development, implementation, commercialization and improvement of new material forming methods known as Severe Plastic Deformation (SPD) schemes (Boulahia et al, 2009;Haghighi et al, 2012;Han et al, 2008;Laptev et al, 2014;Minakowski, 2014;Nagasekhar et al, 2006;Nejadseyfi et al, 2015;Perig et al, 2013aPerig et al, , b, 2015Perig and Laptev, 2014;Perig, 2014;Rejaeian and Aghaie-Khafri, 2014). The classical SPD processing method is Segal's Equal Channel Angular Extrusion (ECAE) or Equal Channel Angular Pressing (ECAP) material forming technique (Segal, 2004).…”

“…1b. It is very important to note that known approaches in published articles (Boulahia et al, 2009;Haghighi et al, 2012;Han et al, 2008;Laptev et al, 2014;Minakowski, 2014;Nagasekhar et al, 2006;Nejadseyfi et al, 2015;Perig et al, 2013a, b;Perig and Laptev, 2014;Perig, 2014;Rejaeian and AghaieKhafri, 2014;Segal, 2004;Wu and Baker, 1997) have never addressed the possibility of changing the standard rectangular punch shape AD-ad in Fig. 1b for material ECAP through acute-angled Segal dies with 2θ < 90 • .…”

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.…”

“…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.…”