A magnetic Barkhausen noise testing method for corrosion-thinning defects of ferromagnetic components

To address the issue of low precision and complicated signal processing in magnetic Barkhausen noise (MBN) testing, a corrosion-thinning defects testing method for ferromagnetic components based on MBN principle was proposed in this paper. First, the mechanism of MBN variation caused by thinning defects of ferromagnetic components under AC magnetisation was analysed in detail by establishing the theoretical model. Second, the eddy current modulation method for MBN was investigated, along with the influence of thinning defect depths on the signal amplitude. Finally, the detection system was built, and the experiments for thinning defects of ferromagnetic components were carried out. The experimental results indicate that the modulated MBN signals exhibit a strong linear relationship with defect depths, and the detection precision of thinning defects on the backside of the steel plate is 0.5 mm. The peak-to-peak value of the detection signal decreases with the increase in defect width and wall thickness. The method proposed in this paper allows for high-precision measurement of thinning defect depths and provides a novel approach for measuring other parameters based on MBN principle.