Microstructure-Based Creep Strain Modeling of Steel 316LN at 140–275 MPa/600–650°C

In this work, microstructural variables reliant creep model was used to simulate the creep curves of steel 316LN. Model variables include densities of mobile and forest dislocations and average dislocation glide distance. The model assimilated hardening, recovery, precipitate growth, and cavitation damage to address the creep behaviour. As an output, model is capable of delivering the creep strain, as well as the evolution of each microstructure dependent variables. Theoretical creep curves are compared with the experimental creep data and reasonable agreement was obtained. The model predicts the important parameters that affect the creep behaviour, such as densities of mobile and forest dislocations, average dislocation glide distance, internal stress, effective stress, dislocation velocity and mobility. Furthermore, the evolution of aforementioned parameters with ongoing creep parameters is discussed meticulously. It can be deduced that the synergistic effect of an increase in dislocation number density leads to pile-ups at coarse particles resulting in the formation of cavities, and the coarsening of precipitates leads to failure of this steel.