This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE TRANSACTIONS ON MAGNETICS 1 Evaluation of Local Anisotropy of Magnetic Response From Non-Oriented Electrical Steel by Magnetic Barkhausen Noise Youliang He 1 , Mehdi Mehdi 1,2 , Erik J. Hilinski 3 , Afsaneh Edrisy 2 , Shruthi Mukundan 4 , Aida Mollaeian 4 , and Narayan C. Kar 4 1 CanmetMATERIALS, Natural Resources Canada, Hamilton, ON L8P 0A5, Canada 2 Department of Mechanical, Automotive, and Materials Engineering, University of Windsor, Windsor, ON N9B 3P4, Canada 3 Tempel Steel Co., Chicago, IL 60640-1020 USA 4 Department of Electrical and Computer Engineering, University of Windsor, ON N9B 3P4, Canada 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. Index Terms— Anisotropy, electrical steel, magnetic Barkhausen noise (MBN), magnetic properties, texture. I. I NTRODUCTION N ON-ORIENTED electrical steel sheets used in electric motors are usually produced from cast ingots through a series of thermomechanical processing steps such as hot rolling, annealing, cold rolling, and final annealing. The thin sheets are then punched and stacked to form a magnetic core, which is subsequently wound with wires around the radial teeth. To maximize the magnetic flux density and reduce the core loss, it is desired that the easy axes of the crystals (h100i for iron) be aligned to the magnetization directions, i.e., along all the teeth in the magnetic core [1]. This requires that the magnetic properties in all the directions of the sheets be opti- mal and uniform. However, during thermomechanical process- ing, anisotropy is inevitably induced, while the magnetic properties of non-oriented electrical steel are usually measured by the Epstein frame method [2] in the rolling and transverse directions only. For better design of motors, the magnetic properties of the sheets in all the directions should be known. Currently, there is lack of such a device that can conveniently measure the local magnetic properties in all the directions although some magnetic methods do exist [3]–[9]. In this paper, a relatively new technique, i.e., magnetic Barkhausen noise (MBN) analysis [10], [11], is utilized to characterize the local magnetic response of electrical steel sheet in various directions of the sheet plane. The measured MBN is then Manuscript received March 16, 2018; revised May 12, 2018; accepted May 28, 2018. Corresponding author: A. Mollaeian (e-mail: mollaei@uwindsor.ca). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TMAG.2018.2844738 correlated with the crystallographic texture, which is one of the main factors that affect the anisotropy of the material. II. MATERIAL AND EXPERIMENTAL PROCEDURE The material used in this paper is a non-oriented electrical steel containing 0.9 wt% Si. The steel was cast, hot rolled, annealed, and cold rolled to sheets of ∼0.5 mm in thick- ness [12]. The thin sheets were then annealed at different temperatures (600 °C, 650 °C, 700 °C, and 750 °C) for 30 s to produce microstructures containing various fractions of recrystallized grains. The texture and microstructure of the steel were characterized by electron backscatter diffraction (EBSD) on the normal direction–rolling direction (RD) cross sections. MBN was measured on the sheet surface using a Rollscan 350 MBN analyzer [13], [14], with the sensor aligned at different angles (0°–360°, 30° interval, plus 45°, 135°, 225°, and 315°) to the RD (Fig. 1). The frequency used for the MBN measurements was 125 Hz, and the peak voltage for magne- tization was 5 V (default values of the Rollscan 350 system). The MBN measurements are very sensitive to the sensor geometry as well as to the contact condition between the sensor and the sample. Thus, a general purpose sensor was used in this research, and a sample platform with precise rotation, tilting, and translation controls was built to ensure repeatable measuring conditions between the sensor and the sample surface. Surface magnetic permeability may also be used to mitigate the uncertainty [9]. Since MBN is a surface measuring technology, the information obtained is essentially only from the near surface region of the sample. The depth of penetration is dependent on the magnetization frequency 0018-9464 © 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.