Small-angle neutron scattering study of the wet and dry high-temperature oxidation of alumina- and chromia-forming stainless steels

Foils of T347 and an alumina-forming austenitic (AFA) stainless steel were oxidized at 800 °C in dry air, air with 10% H2O, and air with 10% D2O. Significant changes in the small angle neutron scattering (SANS) signal were observed for the T347 stainless steel as a function of oxidation time in dry air whereas the AFA alloy showed no significant scattering changes resulting from oxidation. For both alloys, similar scattering was observed in dry and wet air (H2O and D2O) exposure, indicating that watervapour did not result in significant H/D retention or induce significant morphological changes in the oxide scales.

► SANS data was obtained for oxidized alumina- and chromia-forming stainless steels.
► SANS scattering increased with dry air oxidation time for T347.
► Oxidation of AFA stainless steel did not result in significant SANS scattering.
► SANS scattering from oxidation was not significantly modified by watervapour exposure.
► SANS results indicate watervapour did not alter nanoscale oxide porosity.