Effect of Grain Boundary-Magnetic Domain Interaction on the Magnetization Behavior of Non-Oriented Electrical Steels

Magnetic properties of electrical steels such as magnetic permeability and electrical losses are mainly related to chemical composition, crystallographic orientation, and microstructure. Several models have been proposed to empirically correlate magnetic properties and microstructural parameters. A quantitative model based on physical understanding of the interaction between the magnetic field variables (e.g., domain structure) and local microstructural variables (e.g., grain orientation and misorientation, grain boundary planar inclination) is still missing. To obtain a better understanding of the interaction between grain boundaries and domain walls, the magnitude of free pole density at grain boundaries was taken into account. Experimental results from three-dimensional EBSD experiments were employed to measure the grain boundary orientation for several samples with different chemical composition and grain size. The free pole density was calculated using the relative misorientation between adjacent grains and was included in the model together with grain size, magnetocrystalline anisotropy energy, and silicon equivalent. By comparing modeled and measured values of magnetic induction measured at low, medium, and high magnetic fields, it was shown that the magnetization behavior can be more accurately predicted when the grain boundary characteristics are taken into account.