Due to their unpredictability, rapid growth and difficulty of detection, localised forms of corrosion represent a threat to human life and the environment. The current empirical and semi-empirical approaches used by engineers to hinder corrosion damage have several disadvantages and limitations. In this regard, numerical approaches can be a valuable complement. However, the majority of the numerical techniques currently available in the literature are based on partial differential equations, which become invalid in the presence of field’s discontinuities such as cracks and sharp concentration gradients. In order to overcome these limitations, a recently introduced continuum theory of mechanics based on integro-differential equations, peridynamics, is used for the first time for the modelling of polycrystalline fracture, stress-corrosion cracking, pitting corrosion and crack propagation from corrosion pits in steels exposed to different corrosive environments. The results are validated against experimental data and other numerical results.It was found that the microstructure can have a significant impact on the fracture behaviour of the material, and that aqueous solutions of sulfuric acid can lead to an embrittlement of high-strength steels so severe that the material can fail at stress intensity factors even four times smaller than the value of the fracture toughness. It was also found that peridynamics can be successfully used to reproduce realistic pit morphologies and to model microstructural effects, such as the presence of clusters of cathodic intermetallic particles, which can channel the propagation of corrosion pits. Finally, it was demonstrated that peridynamics can also be used to simulate crack nucleation and propagation from corrosion pits, without the need for any assumption on the location of crack nucleation, which, in contrast, is needed when using other numerical techniques. In conclusion, the results of this study support the idea that the peridynamic models produced as part of this research can be helpful in failure analysis and in the microstructural design of new fracture-resistant and corrosion-resistant materials.
|Date of Award||12 Dec 2016|
- University Of Strathclyde
|Sponsors||University of Strathclyde|
|Supervisor||Erkan Oterkus (Supervisor) & Atilla Incecik (Supervisor)|