Abstract
X-ray sterss measurement is an excellent way to trace non-destructively the process of stress generation at the oxide/steel interface and its relation to the structural and compositional changes of the oxide and steel during high temperature oxidation.
Mild steel (1.16wt% Mn, 0.2wt% C) was oxidized in air over the temperature range of 250°C-500°C, the stress and the lattice constants of steel and oxide were measured by X-ray stress measurement with Cr-Kα characteristic X-ray.
A gradual decrease of lattice constants was obsvered in steel over 100hrs oxidation at 500°C, while those of pure iron, and of steel measured by Co-Kα X-ray, under the same oxidation conditions, were nearly constant. The oxidation stresses of steel measured by Cr-Kα X-ray were found compressive after prolonged time oxidation in air at 500°C, but those of pure iron, and of steel measured by Co-Kα X-ray, remained tensile. The differences may be attributed to the compositional changes of minor constituents in steel near oxide/steel interface.
