Inhomogeneous Distribution of Second Phase Particles in Grain Oriented Electrical Steels

The second phase particles were observed during the whole manufacturing process of conventional grain oriented electrical steels, exhibiting that the areal density of particles in the center was obviously higher than that on the surface at each manufacturing stage. After hot rolling, the approximately equiaxed grains formed upon recrystallization were present on the sheet surface while the deformation structures were retained in the central part. Thus, the dislocation density on the surface was evidently lower than that in the center and this trend became more noticeable after the first cold rolling. Since new precipitates were mainly nucleated at dislocations during both hot rolling and annealing following cold deformation, the difference in dislocation density resulted in the inhomogeneous distribution of particles through the thickness of sheet. According to this, Goss grains, which were usually found near the surface, tended to grow up more easily during the secondary recrystallization treatment.