Magnetic Non-Destructive Evaluation (NDE) techniques for strain measurement in engineering components

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Safety is of the utmost concern for industries which involve large scale infrastructure such as nuclear power plants and oil and gas transmission pipelines. Failure of this infrastructure can have serious environmental effects, inflict costly property damage, and result in loss of human life. Non-destructive evaluation (NDE) techniques have been developed to inspect engineering components (e.g. oil and gas pipelines, nuclear power plant tubing) to ensure they operate safely and efficiently. The proposed research program focuses on magnetic NDE techniques. Since magnetism is stress-sensitive, these techniques can detect high stress levels in engineering components before failure occurs. The proposed NSERC Discovery grant funding will support on-going work that examines how stresses in steel affect the signals when magnetic NDE methods are used to examine engineering components. On a microscopic level, stresses are not uniform, but partition themselves into different directions in the microcrystals - some directions carry very high stresses, while others carry little stress. Such microscopically distributed stresses are called intergranular stresses. Dr. Clapham's earlier work has shown that magnetism itself is sensitive more to intergranular stresses in particular directions, rather than to the overall stress pattern. This early work was conducted primarily on simple laboratory samples, however in order to be directly relevant to industrial NDE it is necessary to examine intergranular stresses in real engineering components and determine how they create a magnetic signature. The proposed study for NSERC Discovery Grant funding involves an examination of the intergranular stresses and magnetic signatures associated with dents and gouges in real pipeline sections. The understanding gained from this fundamental study will be applied to other industrially-funded work in Dr. Clapham's research group, to improve signal interpretation from magnetic NDE techniques and also to develop more effective NDE instruments. No other group in Canada works in this field, thus the students involved in this work gain highly specialized and sought after skills and training.