Modélisation des textures et de l'écrouissage dans le procédé d'extrusion angulaire à section constante :

Abstract : Equal channel angular extrusion (ECAE) causes a very detailed attention these last years. This process has developed by Segal in 1974 to achieve severe plastic deformation without changing the sample dimensions. By this technique the material can be hardened near to its theoretical limit, at the same time, a very fine microstructure develops (consisting of near nano-crystals). A new analytical model is presented by using a flow function to describe the material deformation in ECAE. Validated by finite element calculations, this new approach allows the simulation of crystallographic textures with polycrystalline plasticity approaches (two models were employed: self-coherent and Taylor). Detailed comparisons were made with experimental textures for copper and aluminium for various ways of deformation (route A, B and C, characteristic of the ECAE). It was shown that the new model describes the evolution of the textures better than earlier approaches like the model of discontinuous shearing. The flow line approach is incorporated into a hardening model based on the dislocation cell structure of the metal. In this way strain hardening is modelled in a fully analytic way up to large strains. The evolution of the crystallographic texture was taken into account with the help of Taylor factors obtained from self consistent viscoplastic polycrystalline simulations. The model calculations led to good agreements with the experimental curves for the material considered (OFHC copper).
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Roxane Arruffat-Massion. Modélisation des textures et de l'écrouissage dans le procédé d'extrusion angulaire à section constante :. Autre. Université Paul Verlaine - Metz, 2004. Français. ⟨NNT : 2004METZ030S⟩. ⟨tel-01750050⟩

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