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Parameters such as GOS (Grain Orientation Spread) or GOS/D (D the diameter of the grain) or GND (Geometrically Necessary Dislocation) densities have been determined for the whole set of grains as well as for subpopulations (smallest grains, largest grains for example).
Thanks to the high indexing speed of the EBSD systems together with the good spatial resolution of the FEG-SEM, it is possible to obtain good statistics in terms of the number of grains and in terms of the number of pixels inside the grains [8].
j For a grain i, the Grain Orientation Spread reads GOS(i) = [ 1/J(i) ] wij (1) where J(i) is the number of pixels in the grain i and wij is the misorientation between the orientation of pixel j and the mean orientation of grain i i Then, for a set of I grains, GOS reads GOS = (1/I) GOS(i) (2) k For a pixel j, the Kernel Average Misorientation reads KAM(j) = [ 1/K ] wjk (3) where K is the number of pixels around pixel number j j For a grain i, the Grain Average Misorientation is GAM (i) =[ 1/J(i)] KAM(j) (4) where J(i) is the number of pixels of grain i i And, for a set of I grains, GAM reads GAM = (1/I) GAM(i) (5) Similar to the KAM(j) values, the misorientations around each pixel over a given step size can be used to determine the density of GNDs (Geometrically Necessary Dislocations) [10,11,12].
Fig. 2: GOS values (in °) versus the % of elongation (for all the grains, for the largest grains and for the smallest grains).
This could be understood on the basis of the high number of available slip systems.

Regarding the microstructure in the longitudinal section of formed specimens, elongation of grains in the central part and grain size reduction in the boundary area are observed.
He also described [2] how a variation of the swaging parameters such as the feed velocity and the number of forming increments influences properties and microstructure of copper wires.
Grain size evolution.
Fig. 8 Grain size (a) before forming, grain size modification after (b) conventional rotary swaging, (c) after the new method.
Bomas, Influence of the number of impacts during incremental forming on the mechanical properties of copper wires, 8th International Conference of Micromanufacturing (2013)

The numbers indicate the boundary misorientations in degrees.
The number and size of deformation micro shear bands increase with straining.
This annealed microstructure consists of layers of equiaxed and elongated grains with transverse grain sizes of 2.1 and 1.1 mm, respectively.
The former ones are free of substructure, while the latter ones involve a number of low-angle subboundaries (Fig. 5d).
Acknowledgements The financial support received from the Ministry of Education and Science, Russia, under Grant No. 14.575.21.0092 (ID number RFMEFI57514X0092) is gratefully acknowledged.

Application of electron backscatter diffraction to grain boundaries V.
This mapping of grain boundary positions is in itself a powerful application of EBSD, because it allows the grain structure to be quantified.
Grain boundary plane determination The macroscopic grain boundary crystallography comprises five independent parameters.
For this reason, nowadays a greater emphasis is placed on the grain boundary plane, and a stereological method for determining boundary plane density distributions, called the 'five parameter analysis', has been developed and used successfully on a number of materials.
(a) Schematic shape of a single grain (b) Representation of a three grain junction.

In the nugget zone, there are a number of fine recrystallized grains and dispersed precipitates at grain boundaries.
In the thermo-mechanically affected zone, the grain size is not uniform and there are a number of precipitates at grain boundaries.
In the TMAZ on both AS and RS, there are a number of small white η phase particles at grain boundaries, therefore the shape of grains can be identified quite clearly.
It is obvious that grain boundaries are covered by a number of white η phase precipitates.
(2).In the nugget zone, onion rings are evident and there are a number of fine recrystallized grains and precipitates at grain boundaries.

It is normally found that an unfavorable grain was eliminated by a favorable grain.
These small grains are usually called chill grains.
Finally this grain disappears during growth.
This means that the number of grains decreased with growth because of grain selection.
This is regarded as the “gradation grain”.

The UFG structure contains a significant volume fraction of grain boundaries and exhibits a high number of lattice defects (mainly dislocations) introduced by severe plastic deformation during the HPT processing.
The largest grain refinement was achieved by high pressure torsion (HPT) [5].
Small grain size (in the nanocrystalline range) leads to a significant volume fraction of grain boundaries which represent obstacles for movement of dislocations.
A high number of defects is created in the UFG specimens in the course of HPT processing.
It has two reasons: (i) The extremely small grain size leads to a significant volume fraction of grain boundaries which provide nucleation sites for the second phase particles.

The {110} texture with the peak at {110}<110> and {110}<221> was observed in this work, however, a large number of experimental of XRD revealed the {110} texture distributed disperse and vary weak Goss texture was formed, which is totally different from the conventional process.
The growth of Goss grains has an significantly incubation period as the increase of grain size is more than double at 975˚C and the grain size of Goss grains is less than the average grain size of matrix after the abnormal growth.
This phenomenon is related to the disappearance of exact primary Goss grains that are swallowed by the abnormal grains.
The dispersed AlN, MnS precipitated at in grains and grain boundaries will naturally inhibit the growth of primary recrystallized grains in grain oriented 4.5% silicon steels, and it will be beneficial for the abnormal growth of Goss grain.  
With the increase of annealing temperture, the size and number of Goss primary recrystallized grains devoloped obvious, which due to the high mobility of the special grain boundaries between Goss grains and γ-fiber grain, as shown in Fig. 5c (Indicated by D and E).

Also characteristic was increasing of the number of bands with increasing of deformation and mutually crossing of the bands.
Increasing of the number of passes through the angular channel favor homogenization of the materials.
Intersections of the bands and shear bands leads to material divide to parallelograms, which at the later stage, with the increase of number of intersecting bands leads to a microstructure homogenization.
The measurements of the grain size reveal that the sample having an initial in annealed-state grain size of about 250 µm reduced to the grain size below 0.25 – 0.32 µm when it was deformed by ECAP process.
The financial support of the State Committee for Scientific Research of Poland under the grant number 11.11.180.653 is kindly acknowledged.

MDF and microstructural evolution Figure 2 shows changes of flow stress with increasing pass number of MDF.
At a strain of = 0.4 (Figs. 3 (a), (d)), i.e. after the 1st pass of MDF, a numerous number of parallel lines appeared in grain interiors.
And the average grain size, d, can be calculated approximately by d = (DL/n)1/2 (2) where n the number of twins included in a packet [13].
Their finding implies, therefore, the important role of grain boundaries on UFG evolution during SPD, i.e., a favored grain refinement along the grain boundary.
Effect of grain boundary sliding becomes important for ductility even at room temperature when grain size becomes submicron order [20].