Evolution of microstructure and ordering in rolling process of Fe-6.5 mass% Si alloy

Abstract

Fe-6.5 mass% Si alloy is an excellent soft magnetic material with good application prospects. After rolling, the structure of the sheet is likely to be heterogeneous along the normal direction. The microstructure and ordering evolution in the thickness range of the sheets during hot-warm rolling process was studied by means of optical microscope and transmission electron microscope. The results show that dynamic recrystallization occurs in the surface parts during the hot and warm rolling processes, where the grains are equiaxed but have high density of dislocations due to the large deformation. The grains in the center part are elongated along the rolling direction. It is also found that in the hot rolled sheet, the center part has lower density of dislocations because of dynamic recovery. Meanwhile, this part has higher ordering content compared with the surface part, indicating that the high density of dislocations can inhibit the formation of ordering in the air cooling process after hot rolling. In the warm rolling process, both of the parts are deformed heavily. Large deformation destroys ordered phases and induces disordering. The ordering content is low in the whole warm rolled sheet.