Influence of lift off on Barkhausen noise parameters of construction steel

The magnetic Barkhausen noise (MBN) measurement technique is a popular magnetic method used for non destructive detection of microstructural changes in ferromagnetic materials. The MBN parameters depend on the gap between the excitation yoke and measured object. To suppress the negative influence of lift off, we tried to find a parameter of the MBN, which could be independent of lift off changing in a practical range. The lift off effect was analysed experimentally on construction steel samples with various levels of carbon content. We found that the amplitude distribution is a promising parameter of MBN in this regard. Measurement results showed that the slope of amplitude distribution was roughly independent of lift off.