A Meso-Scale Model to Describe the Creep Response and Microstructure Evolution of Superalloy IN-718

Abstract

Creep response of Inconel®718 alloy depends on the stress, temperature and its microstructural ingredients. The meso-scale creep models developed for Inconel®718 are usually less focused on the microstructure evolution. Therefore, a physically based creep model is presented that considers the amount and size of strengthening precipitates. The internal variables of the model are the densities of mobile and immobile dislocations, and the mean free path. The developed model addresses the primary and secondary regime of creep and reproduces the creep curves that resemble the experimental ones, along with the evolution of internal variables. Additionally, model outputs are validated using electron backscattered diffraction (EBSD) investigations. It was shown that the immobile dislocation density has the same order of magnitude as the estimated boundary dislocation density from the EBSD analysis. Furthermore, the model suggests that both the dislocation densities, internal stress and climb stress increase over the period of creep. © The Indian Institute of Metals - IIM 2025.