Quantification of the phase fraction in steel using an electromagnetic sensor

The effect of ferrite fraction, in 0.17-0.8 wt% C steels with ferrite-pearlite microstructures, on multi-frequency electromagnetic (EM) sensor readings has been studied. The measured initial relative permeability values agreed well with finite element microstructure model predictions. The EM sensor low frequency inductance value is sensitive to changes in relative permeability and the sensor can measure ferrite fraction in dual-phase steels. Therefore, EM sensors could be used to assess dual-phase (ferrite+pearlite/bainite/martensite) steel microstructures in a non-contact, non-destructive manner.