Modelling of the Mechanical Behaviour of a Chromia Forming Alloy Under Thermal Loading

When metals or alloys are oxidized at high temperature, an oxide film generally develops. Stress induced by oxide growth may influence the structure and the protective properties of the oxide scales. Classical models (taking into account elasticity and/or viscoplasticity and/or thermal mismatches) are able to predict some stress evolution. Moreover, the origin of that stress for isothermal condition must be sought-after in a growth strain related to the formation of the oxide above the substrate. In the present work, details are given on the modelling of stress under thermal loadings. The study is performed considering different thermomechanical behaviours and upgraded taking into account the origin of the different thermal couplings (weak and strong ones). Therefore, comparison with experimental results performed at ESRF allows extracting thermomechanical parameters with numerical values for different configurations (isothermal or with thermal evolution). This allows also investigating different mechanisms occurring at high temperature in chromia.