Effects of strip thickness and silicon content on Magnetic Barkhausen Noise of non-oriented electrical steel at 50∼Hz

Abstract

Magnetic Barkhausen Noise (MBN) can be used for non-destructive evaluation of structural properties of ferromagnetic materials. An EMF due to Barkhausen noise is induced in a coil near the surface or encircling a ferromagnetic material which is subjected to an alternating external magnetic field. MBN measurements were carried out on samples of Non Grain-Oriented (NG0) steel to determine the variation with thickness and silicon content. The results show that the rms value of Barkhausen Noise (BN) amplitude increases with decreasing sample thickness and increasing silicon content. This is explained in terms of eddy current effects which increase with increasing sample thickness and reduce with increasing silicon content. Moving domain walls induce eddy currents in the sample which give rise to effective retarding pressures on the walls which in turn leads to reduced magnetic Barkhausen noise amplitude.