Jivkov, Andrey P

English

The paper presents the results for crack propagation in the 3D microstructure model for a series of experimentally observed fractions of resistant boundaries. Results demonstrate the formation of bridging ligaments by the resistant boundaries and their influence on the crack driving force. It is shown that increasing the fraction of resistant grain boundaries increased the degree of crack tip shielding developed. The crack tip shielding is expected to reduce the crack propagation rate, hence to increase the material resistance to intergranular cracking. The 2D microstructure model is used for simulations with random distribution of boundaries and a series of susceptible and resistant boundaries failure strengths. The influence of stress on crack path and the influence of the susceptible and resistant boundaries failure strengths on crack behaviour are demonstrated. The effects of crack bridging and crack branching are quantified. It is concluded that the fraction and the failure characteristics of the resistant boundaries are the parameters controlling the shielding effect of bridges

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Modelling intergranular crack propagation to aid microstructure engineering. Part II: Results

A comprehensive account of new 2D and 3D mechanical models for studying intergranular environment assisted crack propagation in polycrystalline materials is presented in this first part of the work. The models are developed to eliminate the limitations of the percolation models, used previously to assess resistance of materials to intergranular cracking. The percolation models do not account for the mechanical crack driving force, which limits their applicability. The new models are based on a regular discrete representation of the microstructure of the materials and a binary selection of grain boundaries’ properties, where the grain boundaries are assumed to be either resistant or susceptible to cracking depending on the grain boundary character. The problems solved and methods of analysis of the results presented in the second part of the work are also described

Modelling intergranular crack propagation to aid microstructure engineering. Part I: Models

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Modelling intergranular crack propagation to aid microstructure engineering. Part I: Models

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The University of Manchester - Institutional Repository

The University of Manchester - Institutional Repository