Grain Boundary Characteristics of Isolated Grains in Conventional Grain Oriented Silicon Steel

Abstract

During the secondary recrystallization of GO, isolated grains are often observed in secondary-recrystallized Goss grains (matrix). In an extraction experiment, the crystallographic relations between single isolated grains and matrix grains respectively were investigated in the case of CGO. Although the S5 grain boundary to the Goss orientation was the most frequent in the primary recrystallization texture, no S5 boundary could be observed at the onset temperature of secondary recrystallization; hence it was concluded that the S5 boundary was most mobile in this case. On the other hand, in the case of HGO, it has already been reported that the S9 is most mobile. The reason why the dominant grain boundary may differ for the same Goss orientation could be the temperature dependency of the grain boundary features, i.e., mobility and/or grain boundary energy. Furthermore, the S3 was more mobile than GGB (general grain boundary) at the higher temperature, which corresponded to the lower temperature range of HGO.KEY WORDS: conventional grain oriented silicon steel; grain boundary; recrystallization texture; CSL; secondary recrystallization.ISIJ International, Vol. 47 (2007), No. 6, pp. 890-897 duction 12) and the main inhibitors were finely dispersed MnS and Cu-S. It was cold-rolled to a thickness of 0.34 mm with a reduction of 54.7 %. Primary Recrystallization TextureThe primary recrystallization textures were measured using the X-ray diffraction method before the extraction experiment and evaluated by the complete {100} pole figures measured at 9 kinds of depths from one surface to another throughout the entire thickness. Figure 1 shows the specimen-preparation for X-ray measurement. The thickness of the specimens was around 60 mm. Nine specimens (p1, p2, … , p9) for one series were taken from each 10 % location: 10.3, 19.1, 29.4, 39.7, 50.0, 60.3, 70.6, 80.9 and 89.7 % respectively and three series were measured in order to improve the precision. The data were averaged at each location and turned down at the central location, i.e., the datum at the central location was the average of 3 data and the data at other locations were the average of 6 data. These data were then three-dimensionally analyzed in crystal orientation using the Vector method.13) The intensity of any coincidence orientation, 14) Si, for a recognized nucleus orientation, is expressed as IcSi, which means the percentage for total intensity. In this study, Goss orientation ({110}͗001͘) and its IcSi (iϭ1-29) were calculated. Extraction ExperimentThe specimens, of which the dimension was 0.34 mm (thickness)ϫ80 mm (width)ϫ220 mm (length), coated with the annealing separator, consisting mainly of MgO, were extracted during secondary-recrystallization annealing, which was performed in a 25 % N 2 and 75 % H 2 atmosphere from room temperature to 1 025°C at a heating rate of 15°C/h. They were extracted at 25°C intervals from 850 to 1 025°C. Secondary Recrystallization BehaviorThe microstructures were optically observed and the magnetic properties, flux de...

Developments in the production of grain-oriented electrical steel

“…In recent years, many investigations on the relationship between the primary and secondary-recrystallization texture have been carried out using the CSL and HE models [15][16][17][18][19][20][21][22][23][24][25]. However, these theories cannot explain all experimental observations on abnormal Goss grain growth.…”

Complete Goss Secondary Recrystallization by Control of the Grain Size and Texture of Primary Recrystallization in Grain-Oriented Silicon Steel

“…For example, {114}<481> and {111}<112> both satisfy the coincident site lattice (CSL, Σ9 grain boundary) and high-energy (HE) (grain boundary misorientation of 20–45°) models with Goss orientation, which is advantageous to the AGG of sharp Goss orientation [ 16 , 17 , 18 , 19 ]. Especially for high magnetic induction grain-oriented silicon steel (known as Hi-B steel), these texture components should be enhanced for the high mobility of Σ9 grain boundary [ 20 ].…”

Secondary Recrystallization Behavior in Fe-3%Si Grain-oriented Silicon Steel Produced by Twin-roll Casting and Simplified Secondary Annealing

“…Additionally, it was also found that some specific coincidence site lattice boundaries (CSL, Σ15 and Σ17b) were formed between the island grains and the secondary recrystallized grains. This seems to contradict the CSL secondary recrystallization theory, which indicates that grain boundaries with higher migration are CSL boundaries rather than HE boundaries [30,31]. In fact, the migration of grain boundaries is determined by grain boundary energy and distribution of inhibitors.…”