Analysis of oxide layers on stainless steel (304, and 316) by conversion electron Mössbauer spectrometry

Abstract

Stainless steels of type SUS304 and SUS316 were chemically treated and heated at various temperatures, and the oxide films formed on the surface were analysed by Auger electron spectrometry and conversion electron Mössbauer spectrometry. The outermost oxide layers of stainless steels were enriched with iron and chromium after heat treatment below 600° C and above 700° C, respectively. It was found that at least two magnetic components of iron species were present in the oxide layers of stainless steel heated below 600° C and that the fine particles of iron oxide are produced in the inner oxide layers of the samples prepared by heating at temperatures higher than 700° C. Only paramagnetic iron species were detected in the oxide layers of the stainless steel prepared by chemical treatment. The structures of the oxide layers produced by those heat and chemical treatments are proposed.