Modeling Stress Corrosion Cracking Growth Rates Based Upon the Effect of Stress/Strain on Crack Tip Interface Degradation and Oxidation Reaction Kinetics

Abstract

Quantitative prediction of environmentally assisted cracking such as stress corrosion cracking is one of the greatest concerns in lifetime management and consequent lifetime extension of light water reactors. Continuum mechanics has been applied to quantify the effect of crack tip mechanics on crack tip film degradation and its physical interaction with the oxidation kinetics. Besides such an effect, it has been realized that crack tip stress/strain can significantly affect the oxidation kinetics by a physical-chemical mode. The present paper focuses on optimizing crack tip asymptotic fields, oxidation kinetics laws, and their interaction modes for modeling stress corrosion cracking growth rates. Meanwhile, the physical-chemical effect of stress/strain on solid state oxidation kinetics at the stress corrosion crack tip is emphasized. The criteria for formulating stress corrosion cracking and optimizing input parameters are also discussed.

Comparative molecular dynamics study of fcc-Ni nanoplate stress corrosion in water

“…Furthermore, since the pre-oxidized structures were equilibrated before applying the deformation, we suggest that the reduction of dislocation barriers for the structures in water can be also ascribed to insufficient time for the formation of a stable surface film due to the applied strain rate. This would be consistent with the rupture-slip dissolution mechanism [10,11], since rupture, as indicated by the increased initial dislocation emission barriers, is likely to occur with the pre-oxidized structures in vacuum, whereas dissolution and constant oxidation processes with low-barrier slip increments are applicable to the structures in water. The effects of elevated temperature at 600K can be distinguished most clearly by reduction in dislocation nucleation barriers after transition to the necking failure mechanism (Figure 6a), which occurs earlier than for the analogous system at 300K.…”

“…A more general discussion of solid materials brittleness and crack healing probability, based on a comparison of the electronic bonding structure from DFT calculations on Al and Al 2 O 3 , can be found in [9]. Moreover, analytical models, based on the combination of crack tip mechanics and oxidation kinetics in alloys, have been developed [10][11][12]. The models refer to consecutive stage mechanisms of open surface dissolution, oxidized film formation and thickening, solid state oxidation during steady state passivation and strain facilitated rupture, which produces new open surfaces.…”

Current understanding of radiation-induced degradation in light water reactor structural materials

“…The surface oxide is a double-layer structure: an inner Cr-rich spinel layer and an outer Fe-and Ni-rich spinel layer in PWR water conditions, and an inner Fe-Cr-Ni spinel layer and an outer hematite layer in BWR water conditions. There are proposed IGSCC mechanisms of austenitic SSs in LWR water conditions such as slip dissolution or slip oxidation [207,318], creep and GB sliding [319], and hydrogen embrittlement [320]. In these mechanisms, oxidation plays essential roles for not only the oxidation itself, but also as a source of vacancies and hydrogen atoms.…”

“…Mechanism-based modes for IASCC CGR have been proposed based on slip dissolution or slip oxidation mechanisms of IGSCC, in which CGR is modeled by the oxide rupture rate due to crack tip strain [207,318]. Assuming that IASCC and non-irradiated IGSCC are controlled by the same slip oxidation processes, the models have been applied to IASCC CGR by considering radiation-induced changes, that is, the increase of yield strength for crack tip strain and RIS for oxidation or repassivation rate.…”