An extended mean field approach for modelling realistic grain size distribution evolutions during Discontinuous Dynamic RX and Post-Dynamic RX

Abstract : Mean-field models for Discontinuous DRX (DDRX) have demonstrated for years their ability to reproduce stress and grain size evolutions during hot deformation. However most of them fail to predict grain size distributions, which is necessary to couple DDRX models with Post-Dynamic RX models. Such failure is a consequence of mean field assumptions that prescribe grains to follow the same path in the diameter dislocation-density space. In this paper, an alternative model based on a stochastic approach which permits to deal with the main advantages of mean field models without this limitation is proposed. Results of this new model are successfully compared with experimental data of DDRX and PDRX obtained on a home-made AISI304 deformed up to large strains by hot torsion tests within the range 950 °C – 1150 °C. A comparison with a level-set based full field method of PDRX run on a simplified case is also discussed.