In-situ dynamic monitoring of phase transformation in steels using a multi-frequency electromagnetic sensor

An industrial-scale electromagnetic (EM) sensor is employed to non-destructively and dynamically monitor the microstructural phase transformation for mild steel samples with different thicknesses (3 mm, 6 mm, and 10 mm), high carbon steel (0.76 wt% C) and 2.25Cr–1Mo steel plates. The continuous cooling process of these samples in ambient air (cooling rate of 0.99–7.53 °C/s) on a run-out table is examined. To determine the phase fractions based on the EM sensor signal and measured temperature, a finite element (FE) model for the EM sensor is utilised. The obtained phase fractions are further validated by conducting dilatometry measurements independently, confirming the accuracy of the transformation behaviour and phase fraction determination derived from the EM sensor readings.