INTEGRATED MODELING OF STRESS CORROSION CRACKING IN SUPERALLOYS
Gustavo CastelluccioGrand Ballroom C
The reliability of turbine blades is strongly dependent on the humidity, contamination, stress, and temperature to which they are exposed during operation. In many cases, cracks initiate simultaneously at multiple locations, which can result in crack arrest (shielding) or (coalescence). This presentation will explore an integrated computational and experimental approach that evaluates crack interaction in CMSX-4 superalloy using C-Ring tests with a layer of contaminant salt exposed to 550C. A phase-field model calculates the diffusion of species and reduces the material critical energy release rate accordingly. The model, which is parameterised to enable cracking above a threshold stress, predicts the critical crack spacing that results in shielding or coalescence. In addition, the integration of X-Ray microscopy (XRM) characterisation with FEM modelling demonstrates univocally the role of crack interaction in stress corrosion cracking. We conclude discussing the value of integrating models and experiments to understand complex failure mechanisms.