Evaluation of Local Anisotropy of Magnetic Response From Non-Oriented Electrical Steel by Magnetic Barkhausen Noise

Non-oriented electrical steels are indispensable materials for use in electric motors as magnetic cores. It is desired that the magnetic properties of the steel sheets be optimal and uniform in all the directions in the sheet plane. Thus, knowing the magnetic properties of the steel sheets in all the directions is crucial for the design of the motors. However, the magnetic properties of non-oriented electrical steels are usually measured by the standard Epstein frame method, which normally only gives the overall magnetic properties in the rolling and transverse directions and those in other directions are usually unknown. In this paper, magnetic Barkhausen noise (MBN) analysis is utilized to characterize the local magnetic response of non-oriented electrical steel. By aligning the MBN sensor to all the directions in the sheet plane, angular magnetic response is obtained. The measured MBN is then directly compared to the texture factor evaluated in the same direction. In this way, the local magnetic response of the steel is correlated with the crystallographic texture. It was found that MBN technique was able to detect the difference in magnetic response induced by magnetocrystalline anisotropy if the effect of the residual stress can be eliminated. This would provide a potential technique for the characterization of magnetic properties of non-oriented electrical steel.