On the evaluation of the Bauschinger effect in an austenitic stainless steel—The role of multiscale residual stresses

In this work, a physically based self-consistent model is developed and employed to examine themicroscopic lattice response of pre-strained Type 316H polycrystalline austenitic stainless steelsubjected to uniaxial tensile and compressive loading. The model is also used to explain theBauschinger effect observed at the macroscopic length-scale. Formulated in a crystal based plasticityframework, the model incorporates detailed strengthening effects associated with differentmicrostructural elements such as forest dislocation junctions, solute atoms and precipitates onindividual crystallographic slip planes of each individual grain within the polycrystal. Theelastoplastic response of the bulk polycrystal is obtained by homogenizing the response of all theconstituent grains using a self-consistent approach. Micro-plasticity mechanisms and how theseinfluence the Bauschinger effect are illustrated in terms of the role of residual stresses at differentlength-scales. Overall, predictions are in good agreement with experimental data of the Bauschingereffect and the corresponding meso-scale lattice response of the material, with the latter measured byneutron diffraction. The results demonstrate that transient softening of the material is related toresidual stresses at different length scales. In addition, the (Type III) residual stress at the micro-scaleslip system level extends the strain range over which the tensile and compressive reloading curves ofthe pre-strained material merge.