Modeling Microstructural Development During Hot Working of Ni-Based Superalloy Alloy 680

In this work, dynamic recrystallization kinetics for a nickel alloy are characterized during hot deformation. Gleeble compression testing within a temperature range from 927 to 1149 degrees C is employed to replicate typical forging conditions with strain rate varying from 0.1 to 10 s(-1). Microstructural and flow stress results were analyzed via the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model that describes the mechanisms triggering recrystallization during forging operations. This model considers the significant variables of hot deformation such as temperature, strain, strain rate, and initial structure. The developed model illustrates the dynamic recrystallization fraction and dynamically recrystallized grain diameter within defined temperature ranges based on the JMAK configuration. Results indicate that deformation above 1093 degrees C yields high dynamic recrystallization. Conversely, at lower temperatures, grain structure is highly dependent on strain and strain rate. Validation tests coupling Gleeble compression tests and FE modeling comparisons covering the forging conditions are included in this study.