Grain Boundary Penetration by Lancet Domains in Fe-3%Si Grain-Oriented Steel

We studied the influence of the grain boundary characteristics on the configuration and behavior of domains in the vicinity of a grain boundary in grain-oriented (GO) electrical steel. We evaluated the boundary misorientation and microstructure with electron backscatter diffraction and transmission electron microscopy. We used magneto-optic Kerr microscopy to investigate the magnetic domain structure and the domain wall motion at the grain boundary at various external field strengths. We found that the grain boundary geometry has a pronounced influence on the ability of domain walls to penetrate the grain boundary during the magnetization process. The results show that different external field strengths are required for the magnetic saturation of the regions within GO steel having grain boundaries with different characteristics. A tilted grain boundary with a boundary plane normal making an angle less than 10° to the rolling direction allowed for the easy penetration of the lancet domains during magnetization, suggesting that this type of grain boundary affects the properties of GO electrical steels less negatively.