A Diffusion–Reaction Continuum Damage Model for the Oxidation Behaviors of High-Cr Steels in Supercritical Water

• Published in: High temperature corrosion of materials Vol. 94; no. 1-2; pp. 5 - 25
• Main Authors: Li, Zhanfeng, Wang, Jiong
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2020; Springer Nature B.V
• Subjects: Behavior; Boundary conditions; CAD; Chemistry and Materials Science; Chromium steels; Computer aided design; Computer simulation; Corrosion and Coatings; Damage assessment; Diffusion effects; Finite element method; Heat resistant steels; High strength steels; Inorganic Chemistry; Materials Science; Mathematical models; Metallic Materials; Original Paper; Oxidation; Partial differential equations; Process parameters; Reaction-diffusion equations; Service life assessment; Steel; Three dimensional models; Tribology; High-Cr steels; Oxidation behavior; Numerical simulation; Supercritical water; Diffusion–reaction model
• ISSN: 0030-770X; 2731-8397; 1573-4889; 2731-8400
• DOI: 10.1007/s11085-020-09975-6

In this paper, a diffusion–reaction continuum damage model is proposed to study the oxidation behavior of high-Cr steels in supercritical water. The model is formulated based on a three-dimensional (3-D) setting. By considering the diffusion and reaction effects of free oxygen in a domain of solid material, a partial differential equation named as the diffusion–reaction equation is derived, which contains an oxidation damage variable representing the fraction of the oxidized metal at a local material point. The evolution equation of the oxidation damage variable can also be derived, which together with the diffusion–reaction equation formulates the governing system of the model. To show the efficiency of the model, a 1-D problem is first studied. By taking P92 steel as an example, the values of the parameters in the governing system are determined. Based on the numerical solutions to the governing system, some key features of the oxidation behavior of high-Cr steel sample are analyzed. The influences of the parameters on the oxidation process have also been discussed. The model is further implemented into the ANSYS UserMatTh subroutine. Then, some typical examples of FEM simulations are introduced. It can be seen that our current model is suitable to simulate the global oxidation behaviors of high-Cr steel specimens with different geometrical shapes and subject to different boundary conditions. Therefore, the model would be helpful for the design and residual lifetime evaluation of high-Cr steel components in practical applications. Graphic Abstract