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It was found the grains of pure iron were significantly refined to the submicron size range by an HPT process, and the Vickers hardness of HPT-processed specimens increased with increasing number of turns and distance from the center due to the grain refinement.
Particularly effects of the number of turns in the HPT process and the counter materials in the wear tests were studied.
The number of turns (N) was varied in five conditions; N = 1/4, 1/2, 1, 5 and 10.
Fig. 2 Variation of Vickers hardness with distance from the center (r) for HPT-processed disks through different numbers of turns.
Summary The grains of pure iron were significantly refined to the submicron size range by an HPT process, and the Vickers hardness of HPT-processed specimens increased with increasing number of turns and distance from the center due to the grain refinement.

After 9 pass of MAF, grain size reduced to 2 µm.
Wear mass loss of MAF processed sample reduced, with increased number of MAF passes.
Average grain size of as-received sample was found to be 600 µm, with equiaxed grains, as shown in Fig 2 (a).
After MAF 3 pass, coarse grains are converted into finer grains and shear bands are formed in the place of elongated grains.
As the number of MAF passes increases, shear bandwidth decreases and dislocation density increases, this is the reason for the strength to increase and is called as grain boundary strengthening mechanism.

Length and volume are expressed in number of grid points (gps) and time in the time steps (ts).
The total number of orientation field variables for the two phases were 36.
As the grain boundaries move and grains grow, the pores tend to break away from the grain boundaries.
It is also noted that the relative green density affects not only the average grain size but also the distribution of the grain size in the ceramics [14].
In the final stage, when boundary diffusion becomes dominant, the ZrO2 grains may serve as second phase particles to impede the growth of the Al2O3 grains due to its lower grain boundary energy than that of Al2O3.

Influence of Density on Mechanical Properties for Coarse-grained soil Based on Percolation Theory Yidan HUANG1, a, Lingkan YAO1,b , Jian Wang1,c 1School of Civil Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China ahuangyidan@home.swjtu.edu.cn, byaolk@home.swjtu.edu.cn, ccrest01@qq.com Keywords: percolation; coarse-grained soil; renormalization group; density Abstract.
Coarse-grained soil is the main material of embankment dams, it is one of the major study objectives of soil mechanics.
The natural structure of coarse-grained soil is featured with the point-to-point single-grained structure among particles.
From the definition of fixed points in renormalization group, it can be obtained that (2) When various numbers of h（0≤h≤0.5）are substituted into Formula(2), the corresponding points can be obtained.
On the other hand, for the sandy soil with bigger particle diameter, it is general with the property of uniform-sized particles and obvious single grain structure, which is similar to the established model with the balls of the same diameter as the background.

Further deformation in strain leads to a higher number of banded structures (Fig.1b) and the formation of new, fine sub(grains) in the regions with high density of banded structures (Fig.1c-d).
Thermal diffusivity as a function of number of cycles Fig.5.
Electrical impedance as a function of number of cycles The thermal diffusivity and electrical impedance of ultrafine grained materials has received only limited attention in published literature and it is difficult to formulate general conclusions at this moment.
The UFGs partially formed after ef =12.5, and the number of grains with high- angle boundaries increased with increasing the strain up to ef =30.3.
After deformation at ef =30.3, the near 80 % volume of material consisted of the UFGs with high-angle grain boundaries and average value of grain size was measured as 1.29 µm. 3.

The literature reports a considerable number of research works that deal with grain coarsening phenomenon in FSS welds.
Taguchi's design provides a simple, efficient, and systematic matrices to optimize process parameters by minimizing/maximizing output responses with the minimum number of experiments, considering the high performance of results and the least cost of experiments [16].
Taguchi method is a powerful tool that uses a special design to study the parameter space with small number of experiments through orthogonal arrays [18].
In trial9, the microstructures of the fusion zone (FZ) present a large columnar ferrite number compared to trial 4.
That means that electric current amount passing through coarse grains is higher than that of fine grains of base material.

The increase in the austenitising temperature causes growth of the austenite grains and a reduction of the number of dislocations contained in it, [5,6].
The reduction of the number of dislocations results in a reduction of the number of effective diffusion paths [6,7].
Experimental procedure The austenite grain size has been found by two methods by outlining the grains with ferrite and by the method of special etching after quenching to martensite [9,10,13].
Conclusions A) Studies of austenite grain size in steel CK45E and 41Cr4 As a result of CK45E and 41Cr4 steel austenite grain size studies, the influence of the austenitizing temperature and time on the average austenite grain size in both steels has been determined.
This was why finer austenite grain was obtained during austenitizing of steel 41Cr4.In both steels, austenite grain growth was quicker at austenitizing temperatures higher than 950 0C.

As equiaxed grains are observed at all the cycle numbers, it is believed that dynamic recrystallization occurs during CVCE.
Larger numbers of interior dislocations are present.
It clearly shows in Fig. 4(d) that UFG (ultra-fine grain) structures with grain sizes about 1μm were formed.
The grains are mostly equiaxed and the grain boundaries are sharp and mostly clear.
It is known that large grains in UFG materials contain dislocations while grains smaller than a certain size are dislocation free[12].

With increasing grain size, the activation of the nonbasal slip systems was limited near grain boundaries.
Journal Title and Volume Number (to be inserted by the publisher) � The compatibility effect is reduced with increasing grain size.
In the fine-grain sample, it is found to be grain-boundary sliding (GBS).
(a) grain-boundary region, (b) grain interior.
Journal Title and Volume Number (to be inserted by the publisher) [9] M.

During deformation, the number of low angle boundaries increase, in contrast to DRV, because of transformation from low to high angle boundaries.
These occur inside the grains.
Measurements of these grains have shown that the grain size here is like the initial grain size.
The numbers of elements changed from 8,000 at the beginning up to 18,000 at the end of the process.
A look at the grain shape reveals that the grains in the dead metal zone are still equiaxed.