ABSTRACT
In this chapter, a deformation-mechanism based true-stress (DMTS) creep model is first developed and later extended to include the oxidation effect. Coupled with physics-based failure criteria in terms of the grain ductility limit and critical GBS level, the DMTS model describes the entire creep curve behavior including the primary, secondary and tertiary stages, and predicts the creep life with specified failure mode, i.e. transgranular or intergranular fracture. Furthermore, with consideration of oxidation, it is shown that the DMTS model can truly predicts long-term creep life (> 104 hours) based on short-term creep tests (< 104 hours), as warranted by the physical mechanisms. Demonstrations are shown in comparison with experimental data on Waspaloy, Mar-M 509 and modified 9Cr1Mo steels, which prove that the DMTS model has a huge advantage over the Larson-Miller parameter method that requires a massive amount of creep testing to construct the correlation curve for extrapolation.
