a b s t r a c tA physically-based two-site mean field model has been developed to describe the microstructural evolution due to recrystallization during and after deformation. The model has been applied to predict the recrystallized fraction, recrystallized grain size, and flow stress of 304L austenitic stainless steel during discontinuous dynamic recrystallization (DDRX), post-dynamic recrystallization (PDRX) and grain growth (GG). The model parameters vary with temperature and strain rate but do not depend on grain size. In PDRX and GG regime, the parameters only depend on temperature. The model responds well to conditions with different temperatures, strain rates, strains and/or annealing times. Particular attention is paid to the occurrence of two-stage growth in the recrystallized grain size plots when PDRX occurs. There is a good quantitative agreement between model predictions and experimental results obtained in the different recrystallization regimes, opening the possibility of modeling multi-pass operations compatible with industrial applications.

Abstract. This work is focused on the evolution of the microstructure of Inconel 718 during multi-pass forging processes. During the forming process, the material is subjected to several physical phenomena such as workhardening, recovery, recrystallization and grain growth. In this work, transformation kinetics are modeled in the δ-Supersolvus domain (T>Tsolvus) where the alloy is single-phase, all the alloying elements being dissolved into the FCC matrix. Torsion tests were used to simulate the forging process and recrystallization kinetics was modeled using a discontinuous dynamic recrystallization (DDRX) two-site mean field model. The microstructure evolution under hot forging conditions is predicted in both dynamic and post-dynamic regimes based on the initial distribution of grain size and the evolution of dislocation density distribution during each step of the process. The model predicts recrystallization kinetics, recrystallized grain size distribution and stress-strain curve for different thermo-mechanical conditions and makes the connection between dynamic and post-dynamic regimes.