Modelling Creep Lifetime of Grade 91 Steel Based on Grain Boundary Cavitation

The creep rupture model developed based on creep cavitation is a physically based method for predicting creep life. By combining creep damage mechanisms with experimental data to establish a creep rupture criterion, this approach provides greater confidence in applications across a wide range of stress level (especially low stress long-term creep) and for extrapolation. This study reported the creep lifetime prediction of a creep rupture model based on creep cavitation for Grade 91 steel over a wide range of stress level. A temperature-dependent function was introduced to creep rupture model to assess the accuracy and reliability across multi-temperatures. The results show that the creep rupture model developed based on creep cavitation achieves high accuracy over a wide range of stress level (1MPa to 450MPa) and temperature. The trend of lifetime prediction curves has a good agreement with experimental data, shows great extrapolation potential. More reliable for long-term low-stress creep life prediction.