Raman spectroscopy has been used by various workers to provide a measure of the stresses within
the oxides grown on metal substrates at high temperatures. In this paper, we consider thermally
grown oxides produced on a Type 316 austenitic stainless steel and an iron 3% silicon ferritic steel.
The oxides were grown in air at temperatures of 950oC and 650oC respectively over a range of
times. These oxides have been characterised by producing cross-sections using focused ion beam
milling. The variation of the Raman spectra wave number (He, Ne laser; λ = 633nm) for the oxides
produced on the polycrystalline austenitic stainless steel and the ferritic steel were measured as a
function of oxide thickness. This shift in wave number was a function of stress. For a fixed oxide
thickness on the stainless steel substrate the specimen has been subject to a bending force. A back
face strain gauge fixed to the metal substrate provided a measure of the applied strain. The peak
wave number varied with applied strain. The results are discussed with respect to the potential to
characterise the stresses produced in thermally grown oxides and as a tool to monitor applied stress.
Effect of thermally grown oxides on colour development of stainless steel