The microstructure of Fe-3 mass% Si alloys before secondary recrystallization has been
characterized by analyzing precipitates and grain boundary segregated elements. The samples used
were mainly sheets of Fe-3%Si alloys containing manganese, sulfur, aluminum, nitrogen and tin,
which were decarburized and annealed up to secondary recrystallization. Grain boundary segregation
in primarily recrystallized samples was studied using Auger electron spectroscopy (AES), and
precipitates were analyzed using transmission electron microscopy (TEM) with an energy dispersive
X-ray spectrometer (EDX). AES spectra showed that tin and nitrogen were enriched on grain
boundaries in the Fe-3 mass% Si alloys. TEM/EDX analysis showed that the morphology and
distribution of the fine precipitates such as manganese sulfide and aluminum nitride were influenced
by addition of tin. The characteristic structure formed by secondary recrystallization of grain oriented
silicon steel is considered to be influenced by the fine precipitates and segregation of a small amount
of elements, as the abnormal motion of grain boundaries of the silicon steel was correlated with the
precipitation and segregation of the alloying elements.