Stress-assisted grain boundary oxidation (SAGBO) is one potential mechanism accounting for the detrimental effect of oxygen on dwell fatigue crack growth behaviour. This mechanism is assumed to weaken the grain boundaries by formation of oxide intrusion along the grain boundary ahead of the crack tip. In this thesis, finite element analyses of oxide formation along grain boundary ahead of a stationary crack have been carried out to study the stress-assisted oxidation behaviour and the corresponding evolution of stress state near the crack tip during oxide formation. A coupled stress-reaction model was established, of which the mechanical constitutive behaviour was represented by a microstructure-explicit constitutive model and the oxide formation by multicomponent diffusion and thermodynamics. Two microstructures with different particle distribution were involved in the simulations to study the effect of microstructure on the oxide formation. A criterion for oxide fracture was proposed. In combination with finite element simulations, it was used for prediction of crack growth rate during dwell period. The predicted results were in the same order of magnitude as experimental data and indicates a same trend of the influence of microstructure on crack growth rate as what was observed in literature.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:760397 |
| Date | January 2018 |
| Creators | Fang, Chizhou |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/8518/ |
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