Fig. 1. Optical microstructures of rolled and recrystallized specimens annealed at 220 °C for different times: (a) - (d) representative micrographs at low magnification; (e) - (h) specific areas of interest at high magnification.

Fig. 2. Optical microstructure of the specimen annealed at 220 °C for 7 days: (a) Panoramic image of the whole sample area (10 × 8 mm2) (RD-TD plane); (b) - (d) magnified images of several outlined areas in (a) revealing more details with respect to a few abnormally grown grains with an overwhelming size advantage compared to the rest of the microstructure.

Fig. 3. Optical microstructure of the specimen annealed at 350 °C for 7 days (analogous to Fig. 2): (a) Panoramic image of the whole sample area (10 × 6 mm2) (RD-TD plane); (b) - (d) magnified images of several outlined areas in (a) revealing a more uniform grain size distribution than that in Fig. 2, which is taken as an indication for the absence of AGG at 350 °C.

Fig. 4. Grain boundary misorientation analysis results of the microstructure annealed at 220 °C for 7 days: (a) ND-IPF map of the sampled area containing both very large and small grains (step size: 2 μm, area: 1600 × 1200 μm2, mean MAD: 0.61°). Blue and white boundaries denote high and low angle boundaries (<15°); (b) selected area from (a) with only small grains; (c) and (d) misorientation axis and angle distributions of grain boundaries of very large and small grains, respectively. The color coding denotes the frequency of plotted misorientation axes in the unit triangles.

Fig. 5. Grain orientation analysis results (220 °C / 7 days) for very large grains and small grains in terms of RD-IPF maps (a) and (b) along with the corresponding basal and prismatic pole figures; (c) and (d) pole figures of large and small grains of more than 8000 grains gotten by multi-EBSD measurements; (e) intensity on (11 $\bar{2}$ 0) plane along the outmost circle (α = 90°) with angle β increased. Texture intensity is given in terms of multiples of a random distribution.

Fig. 6. XRD bulk textures of selected specimens: (a) as-recrystallized; (b) annealed at 220 °C for 16 h; (c) annealed at 220 °C for 7 days; (d) annealed at 350 °C for 7 days. Texture intensity is given in terms of multiples of a random distribution.

Fig. 7. Initial microstructure of the recrystallized condition at 200 °C for 1 h prior to grain growth annealing treatments presented in terms of (a) RD-IPF EBSD map (step size: 1.5 μm, area: 1800 × 1500 μm2, mean MAD: 0.68°); (b) GOS map up to 5°. (c) & (d) (0001) <$11\bar{2}0$> and (0001) <$10\bar{1}0$> size distributions of GOS <1° grains depicted in terms of grain number and area fractions.

Fig. 8. Schematic illustration of the solid-state wetting mechanism of grain growth in silicon steel reproduced from [47]. The numbers at the grain boundaries denote examples of their energies.

Fig. 9. Comparison of the fraction of low angle boundaries (up to 15°) present in (a) the initial recrystallized condition, and (b) in the annealed condition at 220 °C for 7 days.

Fig. 10. Schematic illustration for abnormal and normal grain growth occurring in annealed pure magnesium at 220 °C and 350 °C, respectively. The length and the thickness of the arrows represent the magnitude of the impact of boundary mobility and DDG at each temperature. The number of G2 grains was restricted to those with almost an ideal (0001) <$11\bar{2}0$> orientation (c.f. Section 4.2).

Fig. 11. Simulated grain growth microstructures and their corresponding textures at different time increments matching the experimental annealing times employed. (a, f) input EBSD microstructure; (b - e) anomalous grain growth behavior equivalent to annealing at 220 °C; (g - j) uniform grain growth equivalent to annealing at 350 °C. The color of grain boundaries denotes their relative mobility (red is maximum, purple is minimum).

Fig. 12. Quantitative analysis of the simulated growth behavior shown in Fig. 11. (a) temporal grain size evolution for the two cases corresponding to 220 °C and 350 °C; (b) variation of D/<d> with time; (c) variation of the derivative of D/<d> with time. D is the diameter of the largest grain and <d> is the average grain diameter of all grains.