In-situ stress analyses during high temperature oxidation of mild steel and grey cast iron

For a protective effect of oxide layers their density and their adherence to the substrate are essential. These are determined by the phase composition, the morphology and the strains in the substrate and the oxide layer. In order to determine the development of the phase composition and the strain in oxide layers in-situ X-ray investigations are performed. In addition to the in-situ experiments the layer composition, morphology and texture are investigated ex-situ after the oxidation process. The results of the experiments on a mild steel and grey cast iron reveal that the oxide layers develop fibre textures. Epitaxial strains influence the growth strains in the oxide layers. The strains and stresses present in the oxide layers after cooling to room temperature are dominated by the strain development caused by the misfit in the thermal expansion coefficient of the substrate and the different oxide sub-layers.