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Some methods for grain refining were reported [1,2].
After double repeated quenching, there were many coarse grains in steel A and B, but there was no coarse grain in steel C.
Grain refining mechanisms are as mentioned below.
Double R.Q. 1 10 Prior austenite grain diameter [µm] 50 5 * * *Many coarse grains were observed.
(3) An increase in Cr content resulted in the formation of a number of fine carbides in carburized layer of specimen during heating to repeated quenching after carburization.

The SD grains and the SDC grains coated with Ti are selected.
The setting rate of SDC grains is larger than that of SD grains, and setting position accuracy of SDC grain array is better than SD grain array.
SD grains begin to jump at about 20ms in applying voltage time and jumping rate, i.e. number of jumping grain, increases gradually and unstably with an increase of applying voltage time.
The distribution in grain distance of SDC grains is narrower around 1mm in grain distance rather than SD grains.
(4) The setting grain positioning accuracy of SDC grain is better than that of SD grain.

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.

Aiming at the grain-size analyzing result of some shallow sea area sediments, calculates the grain-size parameter by graphical and moment methods separately, studies the correlation of the grain-size parameter results.
Median is the size when the grain content of the cumulated curve of grain distribution is 50%.
The mean size), at last, we can get the moment of distribution if the sum of the size product was divided by the number of grain size.
So we can make sure that the grain-size parameters derived from moment method are the parameters which can be got through the median of sediment grain size.
(8) Remark：—the frequency when the grain size is (standard)；—the grain size of the first i size bound(standard)；n —the sum of the size grouping.

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.

(c) TEM image of WC grains in WC-36Ni3Al Fig.3.
However, round grains in WC-36 vol%Ni3Al composites are more often observed in the largest grains of the Ni3Al binder alloys.
These two families of prismatic planes can have a different affinity to carbon because W atoms on each plane have a different number of W–C bonds [11].
So the WC grain growth is inhibited and finer small WC grain will exist in Ni3Al rich binder alloys.
Hardmetals with “rounded” WC grains[J].

So the austenite grains grew sharply and some grains were abnormally coarse, and the grain size was not uniform.
And with the increase of temperature, the number of lath martensite increased gradually, and the size of lath martensite also increased.
With the increased of heating temperature, the number of carbides decreased obviously.
Therefore, the number of lath martensites increases gradually.
According to the analysis, when the heating temperature was 790 °C, the ferrite content in the quenched structure was higher, and there was a large number of undissolved carbides, so the hardness and strength were relatively low.

There were a number of bright second phase particles distributed along rolling direction in the matrix (Fig.1(a)).
Higher magnification shown that there were a number of small bright particles at grain boundaries and in the grains, see Fig.1(c).
After 5s, it seems that GBs and SGBs were attacked slightly, and were decorated by a number of discontinous black pits.
From Fig.3(a), a number of white round or elliptic S phase particles located in a REX grain can be seen.
Due to corrosion of quench-induced η phase particles (Fig.1(c)), a number of black pits could be seen in the REX grains and in some subgrains (Fig.3(a)&Fig.3(c)).

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)).

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.