Comparison of the Electric Properties and ESCA Result of Oxide Films Formed on AISI 316L Steel in Simulated BWR Conditions during SSRT
A possible approach to describe the role of the environment in the phenomena behind crack initiation and crack propagation in stress corrosion cracking (SCC) is to assume that the transport of species through the oxide film on the material surface is one of the rate-controlling factors. The transport rates of ionic and electronic defects through the oxide film are, in addition to the environment, also affected by the stress and strain applied to the bulk material. In this paper, the surface oxide film formed on AISI 316L steel in slow strain rate tests (SSRT) in simulated BWR condition has been analyzed by using Electron Spectroscopy for Chemical Analysis (ESCA). The obtained film composition and structure have been combined with in-situ contact electric resistance (CER) measurements in order to evaluate the changes in oxide film electric properties during straining in the above environment. The results show that oxide film resistance of the strained part exhibits a maximum at around 2% of strain, which seems to correlate with a maximum in the Cr(III) concentration in the inner layer of the oxide. The implications of these results to SCC are discussed based on Mixed-Conduction Model (MCM).
Kikuo Kishimoto, Masanori Kikuchi, Tetsuo Shoji and Masumi Saka
Y. Takeda et al., "Comparison of the Electric Properties and ESCA Result of Oxide Films Formed on AISI 316L Steel in Simulated BWR Conditions during SSRT", Key Engineering Materials, Vols. 261-263, pp. 925-930, 2004