The evolution of cube ({001}) texture in non-oriented electrical steel

Abstract

Due to the alignment of two easy 〈100〉 axes in the sheet plane, the cube orientation ({001}<100>) is an ideal texture for non-oriented electrical steel sheets used as core lamination for electric motors. However, this magnetically favorable texture was rarely able to be produced using conventional rolling and annealing routes in non-oriented electrical steels. In this research, inclined cold rolling − a simple rolling scheme to alter the initial texture before cold rolling − was applied to a 2.8 wt% Si non-oriented electrical steel, in order to intentionally “create” a rotated Goss ({110}<110>) texture before cold rolling, which was not commonly observed in hot-rolled electrical steels. Plane-strain compression (rolling) of the rotated Goss was able to produce cube crystallites within the matrix, at the grain boundaries and within the shear bands of the deformed rotated Goss grains. The cube crystallites within the shear bands had lower stored energy than their surroundings, and served as the initial seeds for nucleation. Upon annealing, the cube crystallites preferentially nucleated from the shear bands and competitively grew out of the surrounding substructure, forming a strong cube texture in the final sheet. The formation of the initial cube crystallites within the shear bands of the deformed microstructure was believed to be necessary for the development of a final cube texture in the annealed electrical steel sheet. Although inclined rolling may be difficult to be implemented in industrial production, its unique capability to produce uncommon initial texture before cold rolling provides an interesting technique for the study of texture involution during thermomechanical processing.