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Results and Discussion Analysis of the evolution of the microstructure showed that low-alloy steel grade 18G2S in the initial state (after homogenizing annealing) has a perlite-cementite structure, secondary cementite is located along the grain boundaries (Figure 1), the average grain size is 25 microns.
Despite the high density of dislocations, a large number of dislocation-free subgrains are also observed (Figure 2a).
The detected recrystallized grains differ not only in the absence of dislocations in the grain body, but also in the close-to-equilibrium structure of the disorientation boundaries, as evidenced by the weak banded electron-microscopic contrast at these boundaries.
Based on the statistically processed results of mechanical tests, the average value of properties was determined (where Xi is the result of a separate test, n is the number of tests) and graphs of the dependence of strength and plastic properties on the number of passes were constructed.
Perezhogin, Grain refinement, texture, and mechanical properties of a magnesium alloy after radial-shear rolling, Journal of Alloys and Compounds. 774 (2019) 969-979

Macroscopic behavior of this system is determined by the properties of individual grains, by the mechanical and physical processes run in grains and interaction of grains.
The random shape of grains and orientations of grains crystallographic axes dictates to use statistical methods.
The polycrystalline aggregate is domain of volume Ω consisted of subdomain (crystallites) with volume , , N - full number of crystallites in the body.
For practical application macroscopic quantity of grains N (millions) can be replaced by finite but big number M (tens of thousands) that is statistically representational to N and yet M<For cubical grains the numerical results differ from these ones for spherical grains by few percents.

This is facilitated by dislocation slip across the grains leading to the formation of pile-ups at adjacent grain boundaries [5,6].
It is proposed that this metallurgical condition can be satisfied by the material possessing a significant number of high angle grain boundaries, as these allow easy climb of dislocations at boundaries.
A number of microstructural and thermo-physical parameters need to be specified for numerical integration of Equation-set (3)-(10).
The influence of grain size is also shown.
Illustrates the effect of grain coarsening (evaluated at 900oC).

The grain size of the two steels was refined to 5-9 μm.
Controlled rolling and cooling can improve the performance of steel by controlling the number and size of martensite/austenite (MA) islands of the microstructure in steel [6-8].
The elongation of steel also increased with grain refinement.
The grains were significantly elongated and distributed in a fibrous shape.
The grain size of the two steels was refined to 5-9 μm.

In this formula, M is one of the cations Li, Mg, Ca, Y and most rare earths with valance of +v, m is number of Si-N bonds in α-Si3N4 replaced by Al-N; n is the number of Si-N bonds in α-Si3N4 replaced by Al-O; and and x is the cation solubility (x=m/v) [1].
α-SiAlON grains, that contain a small amount of sintering additive are light gray β-SiAlON grains without any additive are black and the cation rich grain boundary phase appear white.
Some of the α-SiAlON grains are elongated which is believed to be a result of having a high amount of grain boundary phase.
After removing the grain boundary phase, individual α and β-SiAION grains were obtained for SEM and EDX analysis.
α-SiAlON grains are determined according to their morphologies since they are generally considered to occur in equiaxed grain morphology [8].

By contrast, it was shown that after solution treatment, the eutectic phase at the grain boundaries decreased, a little secondary twin grains and some petal-shape phases were founded inner the grains.
It reveals that the grain refinement by dynamic recrystallization was effective and the average grain size was about 2~3μm.
The Mg-RE phases dispersed along the grain boundaries or inner the grains.
The increase of dislocations number and the phenomena of dislocations interacted and twisted near the grain boundaries were observed.
For Mg-2.7Nd-1.2Gd-0.4Zn-0.3Zr alloy, the alloying RE content was low, and the precipitate phase volume fraction or number density was not high even after aging treatment (Fig.10(a)), so the strength increase after extrusion and aging is not obvious.

The crevices between grains were partially sealed on the irradiated surface with 1 shot because the grain clusters on the irradiated surface was remelted in local region [Fig. 2(d)].
The diameter and the number of craters all decreased, and a few microcracks emerged on the irradiated surface originated from the crevices between the separated grains.
With increasing the shot number to 10, a large local region including more grains was remelted and the remelting region connected with the adjacent zone [Fig. 2(h)].
Note that some craters with diameter larger than 2 µm appeared on the remelting region not only originated from the grain tips but the grain boundaries on the non-irradiated surface.
After HIPIB irradiation at 1 shot, the tips of columnar grains were partially ablated, and the surface remelting led to rounding of column grains.

Design cycle of the Laval nozzle Grid Ultimate design Initial design Model building Flow field number modeling Modifying Model building and grid.
The initial grain size is in the range of 0.2-0.5um.Fig.7. shows the TEM micrographs of nano-structured layer (about 3um thickness) of the sample.
The average grain size in the surface is approximately 20nm.
From the dark field image, one can see nanoscale grains of which the shape is roughly equiaxed.
These grains possess random crystallographic orientations, as indicated in the selected area diffraction (SAD) patterns.

It is known that grain boundary properties are strongly dependent upon the types and structures of grain boundaries [1].
The GBCD (i.e., grain boundary misorientation and grain boundary character distribution) was measured by the electron backscatter diffraction (EBSD) technique.
The Co-33Ni alloy (Fig.1b) shows a recrystallized microstructure consisting of a mixture of coarse grains and fine grains.
A great number of annealing twins are observed in the recrystallized microstructures of both the Co3Ti and Co-33Ni alloys.
RD TD crostructure consisting of equiaxed L12 grains, while Ni-25Fe(D) (Fig.1d) show a recrystallized microstructure consisting of fcc grains.

A number of references [3-8] have reported the forming condition of {111} texture in IF steels, but few of them have paid attention to the difference in formation for {111}<112> and {111}<110> texture.
The microstructure of grains belong to {111}<112> component contains large number of subgrains, which integrate, coarsen and further form recrystallization nuclei with annealing time.
Secondly, interstitial carbon and Fe3C concentrate around grain boundary in low-carbon steel, which results in a higher ratio of hardness between grain boundary and inner grain.
Consequently, low fraction {111}<110> grains become dominant by consuming {111}<112> grains.
(2) Newborn grains with {111}<110> orientation are formed by mean of preferred nucleation during recrystallization on the boundaries between {112}<110> and {111}<112> grains; while {111}<112> grains nucleates within deformed grains with the same orientation through subgrain coalescence.