In situ and ex situ characterisation of oxide films formed on strained stainless steel surfaces in high-temperature water

Yoichi Takeda, Tetsuo Shoji, Martin Bojinov, Petri Kinnunen, Timo Saario

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

A possible approach in describing the role of the environment in the phenomena behind initiation and propagation of a stress corrosion crack is to assume that the transport of matter and charge through the oxide film on the material is one of the rate-controlling factors. Straining of the bulk material may affect the transport rates of ionic defects, such as vacancies and interstitials, through the oxide film. The aim of the present work has been to verify the applicability of combined slow strain rate tests (SSRT) and contact electric resistance (CER) measurements to assess the influence of strain on the electric properties of oxide films on AISI 316L stainless steel with or without prior cold work in simulated boiling water reactor (BWR) coolant conditions. The SSRT-CER measurements have been combined with ex situ characterisation of the oxide films after experiments using electron spectroscopy for chemical analysis (ESCA) and scanning electron microscopy (SEM). The results suggest that the effect of strain on the resistance of the oxide films seems to correlate with the effect of the same parameter on the Cr(III) concentration in the inner layer of the oxide. In addition, important differences between the concentration of Ni and Fe in the outer layer formed on stressed and unstressed surface have been observed. Based on the mixed-conduction model for oxide films, an attempt is made to evaluate the effect of straining on the electric properties of the oxide films and to correlate these effects with the changes in film composition and structure.

Original languageEnglish
Pages (from-to)8580-8588
Number of pages9
JournalApplied Surface Science
Volume252
Issue number24
DOIs
Publication statusPublished - 2006 Oct 15

Keywords

  • Contact electric resistance
  • Kinetic model
  • Oxide film
  • Simulated nuclear reactor coolant
  • Slow strain rate test
  • Stainless steel

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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