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Title: Electromagnetic techniques for on-line inspection of steel microstructure
Author: Zhu, Wenqian
ISNI:       0000 0004 2740 1453
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2013
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This thesis covers two main topics- the development of Electromagnetic (EM) on-line microstructure inspection system for steel under controlled cooling and the investigation of using EM sensor to measure rail decarburisation depth off-line.First, through extensive Finite Element Modelling (FEM) the link between EM sensor output and steel microstructure has been found. Both zero-crossing frequency for real inductance and the peak- frequency for imaginary inductance are linearly proportional to magnetic permeability of steel which is an indicative for microstructure. Furthermore, the response of the complex H-shaped ferrite core sensor is found can be described by a simple analytical model of an air core sensor after normalization. In addition, the factors that might affect sensor performance are been investigated, including lift-off, rollers and industrial housing.Second, experiments were carried out both in the lab and at the service line of Tata Steel to check the sensor performance. Test results show the Multi-frequency Impedance Analyser (MFIA) system works very stable in real industrial setup with good performance in signal to noise ratio. It can successfully distinguish samples with different magnetic properties (paramagnetic and ferromagnetic).After that, the possibility to apply EM sensor in off-line rail decarburisation depth test is investigated. Both FEM simulation and experiment results show the decarburisation depth has a linear relationship with inductance. Also the EM sensor output has a good agreement with the predicted decarburisation depth (Fick’s law) and measured results from other methods (micro-hardness and visual test).
Supervisor: Peyton, Anthony Sponsor: TATA Steel
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available