Investigating the evolution of U-10Mo fuel foil microstructures during multi-stage hot rolling using coupled potts model-finite element method simulations

In this work, we study the microstructural evolution of U-10Mo foils over multiple stages of hot-rolling and reheating using our previously validated method coupling the Kinetic Monte Carlo Potts Model with the finite element method. Hot rolling and reheating refine the U-10Mo foil microstructure, but the relationships between the foil microstructure and recrystallization behavior over multiple successive reductions have complex relationships with the rolling schedule that have not yet been well quantified. Simulations were employed to forecast the impact of hot rolling reduction per pass, grain size variations, and uranium carbide (UC) distribution on the Johnson Mehl Avrami Kolmogorov (JMAK) recrystallization kinetics of the U-10Mo alloy, as well as it's post-rolling grain growth kinetics. Initial homogenized grain sizes varying from 100 µm to 1 mm and UC volume fractions ranging from 0 to 2 vol% were parametrically evaluated as a part of this study. While some of our simulation results support the findings of our previous analysis for conditions of single-pass rolling and annealing, our extended analysis shows that the grain size within the as-cast and homogenized foil can lead to significant changes in the in the distribution of strain within the final microstructure, which can slow grain coarsening over the final anneal. The magnitude of the hot rolling reduction per pass had a similarly strong impact on the distribution of strain within the foil microstructure and its subsequent grain growth behavior. The implications of these results on U-10Mo fuel foil fabrication procedures are discussed.