Analytical modelling of intragranular backstresses due to deformation induced dislocation microstructures

M. Sauzay (1)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)

Deformation induced dislocation microstructures appear in Face-Centred Cubic metals and alloys if applying large enough tensile/cyclic strain. These microstructures are composed of a soft phase with a low dislocation density (cell interiors, channels.. .) and a hard phase with a high dislo-cation density (walls). It is well known that these dislocation microstructures induce backstresses, which give kinematic hardening at the macroscopic scale. A simple two-phase localization rule is applied for computing these intragranular backstresses. This is based on Eshelby's inclusion problem and the Berveiller-Zaoui approach. It takes into account an accommodation factor. Close-form for-mulae are given and permit the straightforward computation of reasonable backstress values even for large plastic strains. Predicted backstress values are compared to a number of backstress experimental measurements on single crystals. The agreement of the model with experiments is encouraging. This physical intragranular kinematic hardening model can easily be implemented in a polycrystalline homogenization code or in a crystalline finite element code. Finally, the model is discussed with respect to the possible plastic glide in walls and the use of enhanced three phase localization models.

Keywords: Crystal plasticity; Backstress; Metallic material; Microstructures; Dislocations

Domains: Nuclear Experiment [nucl-ex]

M. Sauzay. Analytical modelling of intragranular backstresses due to deformation induced dislocation microstructures. International Journal of Plasticity, 2008, 24 (5), pp.727-745. ⟨10.1016/j.ijplas.2007.07.004⟩. ⟨cea-02515130⟩