PNNL

Abstract

To achieve the desired microstructure and minimize the thickness variation in rolled foils it is important to understand the effect foil fabrication process variables on microstructure evolution. In this work we developed an integrated simulation of deformation and recrystallization that employs the Finite Element Method (FEM) and the Kinetic Monte Carlo (KMC) Potts Model, respectively to investigate the microstructure evolution during multiple pass hot rolling and heat treatment in polycrystalline U-10Mo fuel. The scanning electron microscopy (SEM) coupled with electron backscattered diffraction -(EBSD) images of microstructures were directly used as input in FEM calculation of deformation, and the calculated strains were used to determine the driving force of nucleation and growth of recrystallized grain in the KMC Potts Model. Along with it grain structures predicted by the KMC Potts Model were used to update the grain structure and material properties for FEM. An iteration between FEM and KMC Potts Model is performed for simulating the grain structure evolution during multiple rolling and heat treatment. The model parameters were first determined by benchmarking the recrystallization kinetics against the experimental data. Then the model was applied to predict the grain structure evolution during multiple-passes of hot rolling and reheating. The results showed that our model can capture the coupling between deformation and recrystallization, and quantitatively reproduce the observed U-10Mo recrystallization and grain growth kinetics. The simulation results demonstrated that the developed model has the capacity to predict grain structures as a function of initial microstructure and U-10Mo foil fabrication parameters.