Non-destructive Eddy current (EC) technique has long been used to detect discontinuities in materials. Recently, its application has been extended to characterize materials microstructure. In order to identify different microstructures, four plain carbon steel bars with different chemical compositions (AISI 1015, 1035, 1045 and1080) were used in annealed condition. The pearlite percentage, carbon content and estimated hardness were determined according to responses of the samples to eddy current. They include primary and secondary voltages and normalized impedance. These data were compared with those obtained from conventional metallographic method and hardness measurements. The results show the high precision of the non-destructive eddy current method in determining the pearlite percentage, hardness and carbon content of mild carbon steels.

Keywords