Barkhausen noise as a function of grain size in non-oriented FeSi steel

The Barkhausen noise was measured in non-oriented steel with different grain size. The change of the grain size was achieved by application of respective thermo-mechanical treatments to the investigated steel. The measurement results of the Barkhausen noise parameters for the sine magnetic flux density is presented and the influence of grain size on the Barkhausen noise is discussed. We explored the noise upon the whole hysteresis loop and not only the average statistical properties of the noise. To clarify different measurement results shown in literature, we explained the influence of the grain size on the Barkhausen noise using two different processes – change of the mean correlation domain volume and change of the number of domains. These two effects can be distinguished by each other by calculating the root mean square value of the Barkhausen noise only for the second half of the magnetizing process and considering only the high frequency spectrum of the noise.

► The mean correlation domain volume rises with grain size.
► The number of domains decreases with grain size.
► Dependence of BN on grain size is not monotonous.
► Measuring conditions change the dependence between BN and grain size.