Modelling and experimental study of magnetic induction spectroscopy for rail decarburisation measurement

This paper presents a modeling and experimental study, based on a magnetic induction spectroscopy (MIS) technique, for non-destructive evaluation of rail decarburization. The inductive sensor contained an H-shaped ferrite core, which was excited with a multi-frequency waveform over the range of approximately 1 kHz to 100 kHz. Finite-element (FE) simulation was carried out to understand the link between EM sensor output and the level of decarburization. Rail samples with different levels of decarburisation, due to different bloom reheat times (85 min-412 min) were tested in the lab. It was found that the zero-crossing frequency in the MIS response is linearly proportional to the decarburisation level of the rails by FE simulation, theoretic analysis and experiment. This finding is helpful in understanding the response of the EM sensor to rail decarburisation and may lead to a non-contact, non destructive method for use during rail manufacturing.