A unified creep life prediction method and fracture mechanism of high-temperature alloys under multiaxial stress.

• Optimized notch acuity ratios can correspond to the notch stress state accurately. • The relationship of notch acuity ratios to skeletal point positions was established. • The predictions of the creep rupture life are in good agreement with the experiment. • The relationship between the void growth rate and the stress triaxiality is revealed. In this paper, a unified creep rupture life prediction method based on continuum damage mechanics under multiaxial stress was proposed. By optimizing the traditional skeletal point stress method, the number of models that need to be computed during the simulation was reduced by 5/6, and the generality of the method for different notch sizes was significantly improved. Creep tests on Ni-based superalloy round bar specimens with different notch sizes, which verify the accuracy of the method, were conducted. Furthermore, creep rupture mechanism analyses were conducted for different notch sizes by combining finite element simulations with experiments, stress and damage were analyzed, and void growth was explained based on triaxial stress states. [ABSTRACT FROM AUTHOR]