PROPOSITION OF THEORETICAL IMPROVEMENT ON MODELS OF PRIMARY WATER STRESS CORROSION CRACKING

摘要

One proposes a theoretical improvement of two existing models for initiation on primary water stress corrosion cracking of Nickel Alloys in nuclear pressure water reactors. These models are the semi-empiric-probabilistic and the slip dissolution/ film rupture. The first includes an equation rated with stress and with thermal-activation. Some authors were showed that the initiation depends mainly on strain or strain rate rather than stress: one departs from Ramberg - Osgood equation and from relationships between stress and strain for Nickel Alloy 600 obtained from slow strain rate tests and constant load tests by Boursier et al., to propose an improvement suggestion which shall be validated. The second one was first formulated by Ford and Andresen and developed by GE laboratories for austenitic stainless steel. One departs from the oxidation film rupture activated by sliding bands and dislocations and which is enhanced through electrochemical Faraday law. It's a well accepted model, but was received critical appointments of authors like Gutman and Hall Jr.: one departs from the own's Gutman theory of mechanochemical interactions to propose a new mathematical equation for this model.