A slip system-based kinematic hardening model application to in situ neutron diffraction of cyclic deformation of austenitic stainless steel

Accurate prediction of the Bauschinger effect is considered a litmus test for the validity of strengthening theories. The effect is known to arise from 'backstresses' having intergranular and intragranular sources. Polycrystal plasticity models inherently capture intergranular effects but typically neglect intragranular (dislocation-based) sources of backstress. The negative impact of this omission is made apparent by comparisons of model predictions with in situ neutron diffraction measurements of the hystereses and internal stresses within a sample subjected to fully-reversed tension-compression cyclic deformation. An elasto-plastic self-consistent (EPSC) model is modified to include a Voce-type non-linear kinematic hardening rule, similar to the phenomenological Armstrong-Frederick-Chaboche model, but implemented at the slip system level. This additional physically-based hardening evolution enables the polycrystal model to account for hardening due to reversible, geometrically necessary dislocation structures, such as pile-ups, as well as the more isotropic hardening effect due to forest dislocations. The model accurately predicts the macroscopic hysteresis loops and internal strains observed during the aforementioned in situ low cycle fatigue tests. (C) 2011 Elsevier Ltd. All rights reserved.