Residual stresses in high temperature corrosion of pure zirconium using elasto-viscoplastic model: Application to the deflection test in monofacial oxidation

摘要

The paper is devoted to modeling residual stresses and strains in an oxide film formed during high temperature oxidation. It describes the deflection test in isothermal high-temperature monofacial oxidation (DTMO) of pure zirconium. The model incorporates kinetics and mechanism of oxidation and takes into account elastic, viscoplastic, growth and chemical strains. Different growth strains models are considered, namely, isotropic growth strains given by Pilling-Bedworth ratio, anisotropic growth strains defined by Parise and co-authors and physically based model for growth strain proposed by Clarke. Creep mechanisms based on dislocation slip and core diffusion, are used. A mechanism responsible for through thickness normal stress gradient in the oxide film is proposed. The material parameters are identified using deflection tests under 400 degrees C, 500 degrees C and 600 degrees C. The effect of temperature on creep and stress relaxation is analyzed. Numerical sensitivity study of the DTMO experiment is proposed in order to investigate the effects of the initial foil thickness and platinum coating on the deflection curves. (C) 2015 Elsevier B.V. All rights reserved.