NON-LINEAR DYNAMICS OF THE MORPHOLOGY AT THE OXIDE /METAL INTERFACE OF AUSTENITIC STEELS IN SIMULATED LIGHTWATER REACTOR ENVIRONMENTS AND ITS IMPLICATIONS FORSCC INITIATION

摘要

Initiation process of stress corrosion cracking (SCC) usually takes long precursor and incubation periods. It can be assumed that SCC initiation is a form of localized oxidation or oxide penetration into the metal substrate. In this investigation, apart from fundamental mechanistic studies, the oxide / metal interface morphology after the oxidation of austenitic steels were analyzed. Oxidation tests were performed using circumferential notched round bar specimens in order to study the oxidation under a high stress state. Based on the oxide / metal interface profiles obtained from cross-sectional images of the specimens, characteristic curves for oxidation localization were drawn and parameters that describe the features of oxidation localization in laboratory specimens were obtained. The trends in these localized parameters with oxidation time are compared with samples removed from operated components and a correlation to SCC initiation is discussed.