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Grains Growth.
Recrystallization and Recrystallized Grain Size.
During these tests the specimens were compressed different number of the deformations with variant deformation parameters.
The model is organized following a tree-structure, the depth being equal to the number of passes and each level is divided into two branches, the recrystallized and the unrecrystallized zones, respectively (Fig. 5).
This introduces the complexity of managing an increasing number of different structures throughout the deformation process.

The results of microstructure shows that the second phase particles pinned on grain boundary not only can inhibit the grain growth, but also the grain can be fined.
It is found that the large amount of second-phase particles is pinning on the grain boundary Fig.2（a）（b）, and the distribution on two sides of grain boundary is different.
The results are shown that the movement of grain boundary was inhibited by the segregation of the second-phase particles along the grain boundary.
The fine precipitates are hardly observed close to the precipitation free zone(PFZ) besides the small numbers of coarser precipitates.
(3) The results of microstructure shows that the second phase particles pinned on grain boundary not only can inhibit the grain growth, but also the grain can be fined.

In proportion to the logarithm of the extrusion rate, the number of DRX grains increased monotonically.
With an increase in extrusion ratio from 10 to 20, the DRX grain size decreased by 45%, and the number of DRX grains increased.
However, at extrusion ratios of over 20, the DRX grain size hardly changed, and no systematic change was observed in the number of DRX grains.
(Sample No. 2; extrusion rate: 30 mm/min) Fig. 3 shows the variation in fine grain size and number of fine grains as a result of T6 temper.
At an extrusion ratio of 10, a slight decrease in the fine grain size and slight increase in the number of fine grains are observed.

Grain boundary character distributions of strain-annealed 304 stainless steel Xiaoying Fang1,2*, Xin Zhang 2 , Hong Guo1 , Weiguo Wang 1 , Bangxin Zhou 2 1.
The connectivity of general high angle grain boundary (HAB) network was interrupted significantly by Σ3n(n=1,2,3) boundaries(special boundaries). 1 Introduction Recent studies [1-6] on grain boundary structure have revealed that intergrannular corrosion(IC) depends strongly on crystallographic nature and atomic structure of the grain boundary, and that low energy grain boundaries such as low coincidence site lattice boundaries (CSLBs) or special boundaries (SBs) have strong resistance to IC .
So, the concept of grain boundary design and control, which involves a desirable grain boundary character distribution(GBCD) including high fraction of CSLBs, was proposed for the first time by Watanabe [7] and has been developed and refined as grain boundary engineering(GBE)[8-10] .
The fractions of the different grain boundary types were determined on the basis of the length fraction by dividing the number of pixels of a particular boundary with that of the entire grain boundaries.
Additionally, a fair number of clusters consisted of Σ3-Σ9-Σ27 boundaries were developed in the process of low strain followed by long-time annealing, while the same phenomenon was hardly seen in the process of intermediate strain followed by long-time annealing.

Cube grains are evidently observed in (a) 493K map though their number and size are not so large.
The grains involve numbers of cube ones.
In both samples, the total number of grains decreases gradually during microstructural evolution.
The increase in the number of cube grains for both samples in lower temperature range means that numbers of cube grains appear from inside to surface as described above.
The numbers of S- and Cu-oriented grains decrease with evolving cube texture in both samples.

Effect of grain size on mechanical properties.
(a) Optical micrograph of grain size D=15 μm.
(b) Optical micrograph of grain size D=40 μm.
It can be seen that small-grain-sized TWIP steel appears as a spot of deformation twins(Fig. 4(a)), on the other hand, a large number of deformation twins and twins interior the annealing twins are found in the large-grain-sized TWIP steel (Fig. 4(b)).
On the contrary, it can be seen that large-grain-sized TWIP steel does not have the grain rotation (Fig. 4(d)).

Structural Dependence of Grain Boundary Energy in Fe-based Polycrystals Identified by OIM Measurements P.
The (relative) grain boundary energy of random high angle boundaries has been measured in several Fe-based polycrystals.
As illustrated in fig 3, the energy E15 of an arbitrary boundary between grain 1 and 5 can be related to the energy E28 of one originally selected boundary (between grains 2 and 8) via different paths.
Thus, a further analysis of the energy anisotropy based on the grain boundary character distribution is suggested to complete the grain boundary energy characterization.
The axes are presented in a standard stereographic triangle and a color code associates the energy values with a number of crystal axes.

As shown in figure 4-a, when the bath temperature from 1600℃ to 1700℃, the number of grain and the average radius changes by a big margin, which the grain number reduces about 13.4%, average grain radius increases about 3.42%.
The grain number, when the water lever is 7.5m3/h, has improved 8.45%, and the average grain radius decreases by 12.86% more than the 5m3/h lever.
Therefore, it can be seen, that improving the cooling intensity can make the growth of columnar crystals smaller, and the grain number increase, and the average grain radius decreases.
The number of nucleation will be increase in the lower bath temperature, which will help the refinement of the columnar grain of the ESR solidification organization
(3) On the optimized conditions, the number of the grain nucleation is improved about13.8%, the average grain radius is reduced about 10.61%, the grain size of solidification structure has been greatly refined, and the uniformity of the organization is improved.

Al-Ti-B master alloy is a good grain modifier, and can play better refinement of the aluminum grain.
The corrosion specimens were taken from the gearbox itself, and the series of the sample was numbered A, B and C depending on position in the gearbox.
The more the number of nucleation, the smaller of the grain was.
If the grain was very small, there would be more grains in a certain volume.
The number of grains increased in a certain volume after modification, which resulted that the number of the grain boundaries increased.

Grain Refinement in a Commercial Al-Mg-Sc-Zr Alloy during Hot ECAP O.
Repeated ECAP led to an increase of the number and misorientation of deformation bands.
They propagated from grain boundary regions to the coarse grain interiors resulting in a more homogeneous microstructure.
A detailed model for the dynamic evolution of a new fine-grained structure by (sub) grain rotation and GBS has been given elsewhere [10].
These grains occurred first close to the original grain boundaries and propagated into the grain interiors on further straining.