Finite-element creep damage analyses of P91 pipes

In this paper, uniaxial and notched bar creep test data are used to establish the material behaviour models for two P91 steels of differing strength. The two steels are denoted here as Bar 257 steel, tested at 650 °C and A-369 steel, tested at 625 °C. Single-state variable and three-state variable creep damage constitutive models were used in the investigation. Methods for determining the material properties in the two sets of equations are briefly described. Finite-element analyses are performed using these material properties for a P91 pipe, subjected to internal pressure and end loading. The failure lives of the pipe were obtained, and on this basis, a preliminary assessment of using the two different sets of constitutive equations for failure predictions of high-temperature components under creep damage conditions can be made.