Comparative Study of Creep Behavior in 9Cr-1Mo Steel With Different Prediction Methods

Over the range of variables (temperature and stress) normally encountered in service applications, creep behaviors of 9Cr-1Mo steel were investigated with various models, such as Wilshire model, combination of exponential form and omega (CEO) model, and continuum damage mechanics (CDM) model. First, a series of short-term creep data was prepared to evaluate the material parameters occurring in these models. Then, creep curve, minimum creep rate, and long-term creep life of present 9Cr-1Mo steel were extrapolated with these estimated models. Based on the analysis of obtained results in detail, it suggested that both CDM model and CEO model can give reliable minimum creep rate predictions. However, the most reliable values of long-term creep life are obtained by the CDM model, followed by the Wilshire model and then the CEO model. In particular, the physically based CDM model can provide useful insights into the underlying creep mechanisms. Therefore, the CDM model has promising potential to study the long-term creep behaviors of 9Cr-1Mo steels.