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Figs. 2(d)–(f) show the results for the specimens with large crystal grains.
The stress is smaller in the larger-grain specimen owing to the Hall–Petch effect.
Figs. 3(a)–(c) show results for the specimens with smaller crystal grains.
Figs. 3(d)–(f) show the results for the large-grain specimens.
Acknowledgement Authors gratefully acknowledge support from JSPS Grantsin-Aid for Scientific Research, Grant Numbers 18K03844.

On the other hand, the number of research works as to SPD of commercial medium carbon steels is still limited, because SPD processing is relatively difficult in steels with higher flow stress.
Grains of pearlite with size of ~ 50 μm are lined by the finer ferrite grains (~10 μm in diameter).
These pearlite grains are lined by finer ferrite grains, Fig. 1a.
Finishing ECAP deformation the corresponding effective strain in dependence of number of passes was εef = 2.7, 3.4 and 4 respectively for individual samples.
The deformed microstructure, which resulted from different ECAP straining of steel, related to different number of passes through die channel 500 nm (N= 4 and N= 6 passes) is presented in Fig. 4.

In the different temperature and the same recycle number condition, to the sticky gather force c value and internal friction Angle Ф influence Tests show that fine-grained soils in the same natural freeze-thaw cycle temperature range (5 ° ~ 5 °,-15 ° ~ 15 °, 25 ° ~ 25 °) inside, stick together force c and internal friction Angle Ф value basically all natural freeze-thaw cycle with the increase of number of reduced.
freeze-thaw cycle number (5 times, 10 times, 15 times) function, T（－25o～25o）>T（－15o～15 o）> T（－5 o～5 o）。
Conclusion Taking widely used as a building foundation fine-grained soils in XinJiang region is as the research object, Completed fine-grained soils in different temperature scope and different times as the effect factors of the cycle freeze-thaw cycle, according to the test results obtained fine-grained soils freeze-thaw cycle in different temperature becomes poor scope and different cyclic number freeze-thaw conditions, the shear strength parameters stick together and internal friction angle Ф force c, change law and will c, Ф value change the results applied to the deep foundation soil nailing support, the role that thawing relatively nail drawing force change at the top, analysis of soil nail anchor the soil anchorage effect.
(2) The same natural freeze-thaw cycle temperature range, fine grain shear strength parameters stick together and internal friction Angle force c Ф value, along with the increase of number of freeze-thaw cycle decreases, but with increasing cycles tend to be stable
(4) In this formula (5-1) same freeze-thaw cycles that temperature becomes poor range, fine grain shear strength parameters c, Ф value with the increase of number of freeze-thaw cycle decreases, and soil nail resistance force T values will pull out the increase of number of freeze-thaw cycle with reduced.Acknowledgements: The XinJiang uygur autonomous region of scientific research plan "fine-grained soils freeze-thaw cycle in the physical and mechanical properties of the research and application" (project Numbers: XJEDU2009S41) Corresponding author: Yong Feng E-mail: xjnydxfy@163.com References(In Chinese) [1] Heilongjiang Province Institute of Cold Area Building Research.

According to the initial grain size of 25 µm these measurements show, therefore, that ABE is effective in reducing the grain size of this Mg-based alloy.
The recorded grain sizes, however, were achieved by ECAP process after eight passes, where un-processed material possessed a grain size of 15~22 µm [9].
As the increase of strain, the size of fine grain is less affected by ABE passes, while the coarse grains are refined continuously by dynamic recrystallization [3].
Fig. 3 a) True stress versus true strain at room temperature for as-received and processed experimental alloy, b) Variation of the yield stress, UTS and tensile elongation with the number of ABE passes.
The more the number of passes the more pronounced hardening effect may be seen in the material.

(2) Dgeff and Dgbeff are respectively, the effective B redistribution coefficients in the grains and the grain boundaries.
(4) Di = D0 exp (–Ea/KT) is the intrinsic diffusion coefficient in single-crystal Si, K is the Boltzmann constant, T is the annealing temperature, Ea is the activation energy, p is the holes concentration, ni is the electron intrinsic concentration, Csol is the B solubility limit, β is the ratio of the diffusivity induced by charged vacancies (β=Di+/Di0), m is the medium number of B–Si atoms in small clusters formed within the grains, γgbEnh is a pre-exponential factor for the adjustment of the TED rate within the grain boundaries and Eb is the energy barrier height to the grain boundaries; which depends on the average grain size Lg and the density of trapping states at the grain boundaries Nt [3].
Starting from the simulation we notice that effective B diffusivity in the grain boundaries is only about 200 times faster than that in the grains.
The B exchange between grains and grain boundaries becomes the dominating transport mechanism.
The medium number of interstitial-atoms to be trapped in small Si–B and B–B clusters in grains m takes the value of 2; which leads to the best fitting for all the profiles.

As the tool approaches to the grain boundary, the defects are seen to be accumulated near the grain boundary.
Then, the grain boundary motion is traced.
The initial grain boundary lay in A-A line.
However, the grain boundary bent as B-B line.
Since the number of contact atoms becomes smaller during the lithography than the indentation, the forces summed over the contact atoms are obtained lowest.

The results show that the grain size is affected by the spindle speed.
Increasing the number of passes reduces also the size of the grains and the intermetallic phases in the AZ91 alloy.
The alloy in as-cast condition showed α-grains of about 500µm size and intermetallic phases in different forms at the grain boundaries.
The α-grain size was similar for both rotation speeds, with an average grain size of 6µm.
During process at 900rpm/30mm.min-1 the α-grain size varied from 400nm to 2µm, while the β-intermetallic phase was refined (grain size max. 600nm).

Whenever all grains have the same properties and the strain rate is uniform, every grain's history is the same, which leads to simple analytical calculations.
Eq. (3) means that any grain gives rise to one single grain during its life during the steady state.
Since a number of publications, including the original Derby papers [6], suggested , this led the present authors to choose in their DDRX model [1,2].
Cahn, The impurity-drag effect in grain boundary motion, Acta Metall. 10 (1962) 789-798
Derby, Dynamic recrystallization: the steady state grain size, Scripta Metall.

The marking of samples in presented figures includes the number of ECAP passes and letter M, designating the middle region of rod.
A significant decrease of lattice distortion ε in Cu rods by increase in the number of ECAP passes indicates, that in most grains distinct perfection of the crystalline lattice takes place
(4) The most probable value of dislocation density ρ for Cu rods varies in limits 1x10 13 ÷ 1x10 14 m-2 and decreases with the number of ECAP passes.
Thus, presented PF visualize the texture inhomogeneity through the cross-section of studied rods as well as changes of this inhomogeneity with the number of ECAP passes.
Marking includes number of ECAP passes and region of section (T - top, M - middle, B - bottom).

Fine grain does not appear while the columnar crystal directly grow from the combination layer.This is different from the fine grain zone of the surface, columnar grain zone, equiaxed grain zone which are all formed during being casted.
This is when the laser clads, hexagonal structure α(Mg) solid solution of zone A and Mg matrix are fully coherent, while during the cooling process the grain grow directly as unmelt solid grains of the substrate surface as the nucleation center ,but limited number of the matrix grains result in a coarse columnar grains.
Massive dark figure is Mg2Si phase (a smaller number) by electron spectroscopy (EDS) analysis, we believe it reach zone B by convection and gravity.
Microstructure characteristics shows that a large number of dendrites located in the zone C.According to Electron Spectroscopy (EDS) analysis of figure 5, the coarse dendrites are Mg2Si phase and matrix is mainly β (Mg17Al12) facies.The molten Mg is reacted to Si of Al-Si eutectic alloy in zone C, then a large number of Mg2Si coarse dendrites is formed.
During the cooling process the melted Si separate out in the grain boundaries make the grain boundary coarsening.