Application of a physically-based dislocation creep model to P92 for constructing TTR diagrams

Abstract

To raise the efficiency of thermal power plants, operation temperature and pressure must be increased by improving the creep performance of materials such as martensitic Cr-steels. To understand the underlying mechanisms of degradation, physical creep modelling provides a detailed and profound insight into microstructural processes. For such a physically based dislocation creep model, it is demonstrated that based on a parameter set found for one experimental creep curve, numerous creep curves on different stress levels can be simulated without any additional experimental data. These simulation results are then used for constructing a TTR diagram of P92. We succeeded in extrapolating rupture times for variations in both applied stress and temperature. In all cases, microstructural evolution of the simulated material is considered, including dislocation density, subgrain size and precipitates. The obtained rupture times in the simulated TTR diagram are compared to reference data, achieving good agreement.