Characterization of Chemical Information and Morphology In Decarburized Electrical Steel with Glow Discharge Sputtering

Electrical steel is extensively used for transformation and generators, and the need for more efficient electrical steel has been increased due to the global movement of energy saving and environmental protection. The electrical steel is made up 3% silicon and a majority of iron matrix for increasing specific resistance. The surface of electrical steel is covered with a film composed of mainly Mg₂SiO₄, which is a reaction product of internal oxidation precipitates formed during decarburization annealing and MgO affects not only the electrical insulation properties but also the magnetic properties of electrical steel. Therefore, it is very important to know the morphology and chemical properties of the internal oxidation layer for controlling and understanding high temperature oxidation in the manufacture of electrical steel. Although many investigations on the internal oxidation of 3% silicon steel have been conducted, there have seldom been reports on the growth and behavior of internal oxidation depend on the evaluating temperature in electrical steel sheets. In this study, the internal oxidation layers have been investigated as a function of heating temperature, annealing time and oxygen potential in order to survey the growth and formation of internal oxides during decarburization annealing in the electrical steel. The morphology and growth of oxides were observed by SEM, TEM, FT-IR, and GDS.