Creep Rupture Assessment of New Heat-Resistant Sanicro 25 Steel Using Different Life Prediction Approaches

摘要

The paper deals with creep life and creep strength estimations of Sanicro 25 steel through various continuum damage models and modified extrapolation methods. Four different continuum damage models, i.e., modified K-R model, Dyson model, W-T model and modified W-T model considering the stress-dependent failure strain, were incorporated into numerical simulations using user subroutines so as to analyze the creep strain behavior and the creep rupture time. In the case of 700 degrees C, the predicted creep rupture lifetimes determined from modified K-R model, Dyson model, W-T model and modified W-T model all matched with the experimental data, where the modified W-T model provided the best prediction. However, at 750 degrees C, only the predictions using W-T model and modified K-R model matched with the experimental data. The Dyson model and modified W-T model underestimated the creep rupture lifetime. Besides the creep damage approaches, a modified extrapolation method developed by Wilshire (based on the stress-dependent creep activation energy) was also tested and verified to make predictions of creep lifetime under various stress conditions more easily than the creep damage models. A general comparison of the analyses made with different life prediction methods in Sanicro 25 steel was presented in this paper.