Coupling crystal plasticity and continuum damage mechanics for creep assessment in Cr-based power-plant steel

Abstract

To improve the design and safety of power plant components, long-term high-temperature creep behaviour of a power-plant material, such as Cr-based alloy, should be assessed. Prior studies indicate that power-plant components undergo material degradation and premature failure by nucleation, growth and coalescence of microvoids as a result of creep damage. In classical crystal-plasticity-based models, a flow rule and a hardening law do not account for global stiffness degradation of materials due to evolving microvoids, having a significant influence on material behaviour, especially under large deformations. In this study, a crystal-plasticity scheme coupled with an appropriate continuum damage model is developed to capture the anisotropic creep-damage effect on the overall deformation behaviour of Cr-based power-plant steel. Numerical simulations show that the developed approach can characterize creep deformation of the material exposed to a range of stress levels and temperatures under consideration of stiffness degradation under large deformation.