A numerical approach to determine creep constants for Time-Temperature Parametric methods

This study dealt with how to mathematically obtain creep constants of C, Q/2.3R, T _a and t _a used in Time-Temperature Parametric (TTP) methods. A number of creep rupture data from 550 °C to 800 °C for Type 316LN stainless steel were collected through a worldwide literature survey and experimental data produced at KAERI. It was found that the creep rupture data revealed a linear relationship when the data were plotted by the semilogarithmic coordinates of log (t _r ) versus stress. On the basis of this linear relationship, the creep constants of C, Q/2.3R, T _a and t _a used in the Larson-Miller (LM), the Orr-Sherby-Dorn (OSD), and the Manson-Haferd (MH) methods were obtained by a new numerical method. This approach can be utilized as a useful method to predict the long-term creep life of Type 316 stainless steel.