Modelling the creep curves of RAFM steel employing a dislocation density reliant model

Abstract

The microstructure based creep modelling is one of the important tools to elucidate the creep deformation behavior with ongoing substructure evolution. Present research work embodied the development of hybrid creep model that combines a microstructure based creep model and continuum damage mechanics (CDM) approach for addressing the creep behavior of reduced activation ferritic-martensitic (RAFM) steel. By addition of these two methods, the model is capable to address the creep curves up to a large portion of tertiary creep regime. The model is capable of demonstrating the evolution of the microstructure based variables that are important to understand the microstructural degradation mechanisms during creep. The evolution of dislocation densities (mobile, dipole and boundary), glide velocity, dislocation mobility, mobile dislocation spacing and subgrain boundary energy/unit volume, with ongoing creep is discussed and the magnitude lies in the range of 6.37 × 1012-–1.19 × 1014 m−2, 4.66 × 109 – 4.38 × 1011 m−2, 5.91 × 1013 –2.86 × 1014 m−2, 3.34 × 10-12 − 3.99 × 10-12 m/s, 5.69 × 10-21-7.148 × 10-21 mPa-1s−1, 91.2–395 nm and 2.07 × 1015 - 2.42 × 1017 Jm−5, respectively, at the end of simulation. The simulated creep curves have shown a reasonable match with the experimental ones.