Influence of Magnetizing and Filtering Frequencies on Barkhausen Noise Response

This paper is devoted to frequency issues of the Barkhausen noise (BN) measurements, namely, to investigation of influence of magnetizing and filtering frequencies on the BN response. The measurements were performed for typical industrial steels at controllable magnetizing conditions: fixed induction or field waveforms. A vertically mounted array of three Hall sensors was used for direct determination of the sample magnetic field. The BN signal was detected locally by a surface-mounted pancake coil. In ac magnetizing frequency range, the BN quantities were observed to follow a nearly square root dependence on the frequency, provoking the classical discussion about possible correlation between the magnetic hysteresis and the BN effects. Influence of the filtering frequencies on the BN parameters (reading depth adjustment) was studied on a decarburized spring steel with surface ferrite layers of different thicknesses.