Data for: Creep damage assessment of ex-service 12 % Cr power plant steel using digital image correlation and quantitative microstructural evaluation
The following data is in support of a hypothesis that creep damage between different service exposed X20 piping steels can be effectively deduced from a deformation-based test as well as microstructural-based feature characterisation. Such steels were originally characterised for damage using cavity density. The deformation-based test involves applying a non-uniform temperature profile to an X20 sample using a Gleeble thermomechanical simulator and using Digital Image Correlation to calculate multiple creep strain curves from a single sample. Notably, similar creep rates were found between a low damage material and a medium damage material state, suggesting a similar remnant life between the two despite the latter having a higher cavity density. From this data, threshold stresses, activation energy and stress exponents can be calculated and summarised into a Zener-Hollomn parameter that shows a clear difference between the low/medium damage X20 and the high damage X20. Further investigation into microstructural features using electron microscopy and image analysis software, shows differences in some features between the various ex-service states. Most notably, Laves phase and M23C6 particles play a large role in explaining the observed deformation behaviour. A high M23C6 density in the medium material explains the deformation resistance of this material in relation to the other material states, whilst higher Laves phase densities were found in the medium and high damage materials.