The Origins of the Goss Orientation in Non‐Oriented Electrical Steel and the Evolution of the Goss Texture during Thermomechanical Processing

Abstract

During the manufacturing of non-oriented electrical steel laminations for electric motor or generator applications, the Goss ({110}<001>) texture frequently appears in several stages of the processing. To understand the origin and the evolution of this texture, a non-oriented electrical steel (2.8 wt% Si) is processed through hot rolling, hot band annealing, cold rolling and final annealing, and the origins of the Goss orientation and the evolution of the Goss texture in these processes are investigated by electron backscatter diffraction (EBSD) techniques. It is seen that hot rolling results in a high volume fraction (%30%) of the Goss grains near the surfaces of the rolled plate, but the subsequent hot band annealing significantly reduces it to less than 10%. After cold rolling, the Goss volume fraction further decreases to only about 1%. Three locations of the Goss grains are observed in the coldrolled matrix, that is, those within the shear bands of two symmetrically equivalent {111}<112> grains, those embedded in the microbands of one of the {111}<112> grains, and those at the grain boundaries between the {111}<112> and {113}<361> grains. The formation mechanisms of these three types of Goss grains are explained using a transition band model and a rigid inclusion model.

Recrystallization Behavior of Warm Rolling and Cold Rolling Cr-Ti-B Steel during Annealing

“…Goss subgrains appeared preferentially within striated structures, such as shear bands, in Figure 5a, which resulted in the formation of Goss recrystallization textures at shear bands during annealing. The misorientation between Goss and {111}<112> recrystallized grains was <110>30 • , indicating that the grain boundaries between Goss and {111}<112> recrystallized grains had the highest migration rate [23]. Goss recrystallization could increase by swallowing the surrounding {111} deformed matrix at the initial stage of recrystallization.…”

Recrystallization Behavior of Hot‐Rolled Microstructure with Texture Gradient and Texture of Final Sheet in Thin‐Gauge Electrical Steel

“…At the same time, it is also accompanied by the change of microstructure and texture different from that of conventional thickness. The essential difference between a hot-rolled sheet and a cold-rolled sheet is that there is a significant texture and microstructure gradient along the thickness direction of the hot-rolled sheet (or named texture and microstructure inhomogeneity), [1][2][3][4][5] which is manifested by the presence of the strong shear texture in the surface caused by the friction between rolls and sheet surface at high temperature and typical deformed α-fiber grains in the central layer. The shear microstructure shows that the fine equiaxed grains are dominated by dynamic recrystallization, or mixed structures of equiaxed grains and deformed grains, while the shear textures contain Goss texture {110}<001>, Brass texture {110}<112>, and Copper texture {112}<111> with different intensities.…”

“…The microstructure and texture gradient along the thickness direction of the hot-rolled sheet is affected by not only Si contents and other alloy elements, [4,5,7,9,10] but also by hot-rolled heating temperature, hot rolling finishing temperature, and coiling temperature. [11][12][13][14][15] The thickness of the fine-grained zone with shear orientation on the surface of the hot-rolled sheet varies, [1][2][3][4][5] which affects the competition between the surface layer and the central layer with different recrystallization behaviors during normalization and the normalization temperature or time required to achieve uniform grain size. In short, depending on the extent of microstructure and texture gradients in a hot-rolled sheet, the normalization temperature or holding time to achieve a uniform and coarse-grained microstructure before cold rolling will be different.…”

“…Early studies show this texture as an unfavorable texture in interstitial-free steel or low-carbon steel for deep drawing, [16] which usually forms within coarse initial grain structures after cold rolling with high rolling reduction and annealing. [17][18][19] The formation of {114}<481> texture during cold rolling and recrystallization under the conditions of (112) [1][2][3][4][5][6][7][8][9][10] single crystal, [20] {100} <110> single crystal and Bi crystal, [21] cross rolling, [22] and the initial columnar-grained slab [23,24] has been studied. The results demonstrate that it mainly comes from the vicinity of the grain boundary of {112} <110> deformed grains and also from the uneven deformed region in other-oriented deformed grains with α-fiber orientations.…”

The Effects of Deformation Conditions and Microstructural Features on Typical Textures of a Non-oriented Electrical Steel in Electrically Assisted Forming

“…Numerous investigations showed that deformation conditions such as temperature and strain have great influences on typical textures in non-oriented electrical steel. [12][13][14][15][16][17][18][19][20] The typical textures concerned are desired textures such as Cube ({001} h100i) texture, Goss ({011} h100i) texture, rotated cube ({001} h110i) texture, and h-fiber (h100i//ND) as they have h100i axes which are the direction of easy magnetization and undesired c-fiber (h111i//ND, normal direction). [21][22][23][24] A great deal of experimental effort has been made to produce cube-textured electrical steels.…”