Influences of Composition on the Transformation -Controlled {100} Textures in High Silicon Electrical Steels Prepared by Mn-Removal Vacuum Annealing

Laboratory experiments demonstrate that the magnetic-beneficial {100} texture can be strongly produced using the so-called surface effect transformation treatment either in low-grade electrical steels or in high-grade 3%Si steels. In the latter case, the solid-phase transformation is introduced into Si steels by adding carbon and manganese elements. In addition, vacuum annealing and subsequent wet hydrogen decarburization are needed. Although such treatment differs remarkably from conventional industry production facilities, its superiority of producing extremely sharp {100} texture, immensely high magnetic induction, and low core loss keeps the method attractive for environmental friendly and high efficiency rotating machines. Our previous results indicated that the heavy rolling reduction favors the rotated cube texture {100}< 011 > formation; however, the cube texture {100}< 001 > is expected due to the easiness of sheet cutting for iron core production in the industry. In this study, the influences of compositions on the formation of the cube texture, 25-rotated cube texture, and rotated cube texture were investigated. The phase diagram features of the alloy consisting of strong cube texture were also examined. The aim is to establish the theoretical bases for quantitative control of the alloy composition suitable for cube texture in 3%Si electrical steels. Four steel compositions are designed using different combinations of carbon and manganese contents. Thus, the transformation temperatures, ferrite grain sizes, and pearlite volume fractions will be different, leading to distinct growth rates of {100} oriented grains during vacuum annealing at a constant temperature. They were cold-rolled by 50% reduction, which is beneficial for the cube texture formation. The results of experimental determination and calculated phase diagrams indicate that the alloy with lower carbon and Mn contents in the investigated four steel compositions shows a faster and stronger cube texture in the Mn-removal surface layer. The area fraction of the {100} texture in the Mn-removal layer of the alloy after vacuum annealing at 1100 C for 30 min reaches 77.3%. In addition, the suitable decarburization temperature after the formation of the Mn-removal surface layer is discussed and suggested based on the calculated phase diagrams.