Effects of Laser Cutting on Microstructure and Magnetic Properties of Non-Orientation Electrical Steel Laminations

Non-oriented electrical steel (NOES) is commonly used as a core material in electric machines. These laminations are cut into the desired core shape that modifies the material properties near the cut edge, which consequently changes the magnetic performance of the core lamination. Magnetic property deterioration due to cutting has been reported in the literature but less attention has been given to the microstructural changes due to cutting and its relation to the magnetic properties. The present research focuses on the effects of laser cutting on microstructure and magnetic properties of NOES laminations. A number of lamination steel samples were laser-cut using an identical procedure to that expected on an industrial scale. Property measurements showed that the magnetic permeability of the samples decreased while the core losses increased. The core loss increase was significant, about 22% at 50 Hz and 1.5 T. This was attributed to the change in the micromagnetic characteristics of the sample due to cutting. The change in micromagnetics was investigated using magnetic domain imaging and distorted domain structure was observed near the laser-cut edge. Backscattered electron imaging and nanoindentation measurements were also used for further investigation of micromagnetic properties of the material.