Omar Fernandes Aly and Miguel Mattar Neto Pages 27 - 32 ( 6 )
Background: Stress Corrosion Cracking (SCC) is a sudden and difficult-to-predict severe degradation mode of failure of nuclear, petrochemical, and other industries. This is a review of a development proposal for methodological software for modeling SCC based on: the failure propensity plus a kinetic model link which better describes its evolution.
Methods: The basic issues of this methodology are: a) A fixed combination of material-environmental condition is plotted on a potential-pH (Pourbaix) diagram marked with corrosion submodes – which can be originated from literature and/or experimental data. This forms a Knowledge Base (KB) for SCC-Propensity. Fuzzy Logic- a form of multiple valued logic where uncertainties can be considered - can be used to determine the SCC-Propensity zones; b) When the actual corrosion submode of the concerning material-environment is marked, based on new experiments, a feedback should be sent to the KB with the purpose to check the original submode border; c) Over the determined point (or region) in a SCC submode, a proper kinetic model should be chosen (departing for example from a kinetic library model-KB) to adjust the experimental data from the concerning material-environment. Alternatively a new empiric or numeric model can be adjusted; d) The regression quality of the model adjusted should be properly and statistically evaluated, and a feedback should be “fuzzylogically” retrofit its adequacy.
Results: The main result is prediction with an adequate statistical regression.
Conclusion: In this article the methodology is reviewed with an improving concerning the Pourbaix diagram construction for multielement systems, and at high temperatures.
Light water nuclear reactors, modeling software, Pourbaix diagram, stress corrosion prediction.
IPEN/CNEN-USP – Energy and Nuclear Research Institute, Av. Lineu Prestes 2.242-USP Campus- 05508-900 São Paulo, SP, Brasil.