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With increasing number of ARB cycles (N) the maximum punch force is increased, compare Fig. 3.
Hydraulic bulge testing: Burst pressure (full symbols) and von Mises equivalent strain (open symbols) vs. number of ARB cycles.
The grain structure merges to a bimodal structure consisting of equiaxed coarse grains and elongated fine grains.
For increasing number of ARB cycles the drawability decreases steadily like it is also observed in the bending tests.
All forming experiments equally show an increasing strength with increasing number of ARB cycles.

Others have an impact on the tungsten performance in the first wall, e.g. its high ductile-brittle transition temperature (DBTT), high atomic number (high radiation loss from fusion plasma via impurities) and significant degradation of properties with grain growth [7,8].
In the fine-grained material, He and H ions tend to accumulate at the grain boundaries, thus limiting the development of bubbles within the grains.
Particle size of the initial powder was decreased from median value of 1.2 mm prior to milling (number distribution of the particle sizes in the measured powder) to median value around 250 nm after milling and the overall span of the distribution decreased from 0.43-3.91 mm prior to milling to 0.16-0.52 mm (representing Dn (10) – Dn (90) of the number distribution) after milling.
The particle size distribution of the powders before and after milling; number distribution was chosen to depict the effectivity of the milling process.
Powder milling including powder particle/grain refinement and introduction of higher density of crystal lattice defects and strain caused increase in the hardness number by more than 100 HV1 (compare W0 and WM sample).

The average value of the total misorientation over one sample was increased with the number of cycles.
Number of cycles 0 200 400 700 Average of β (deg.) 0.53 0.58 0.59 0.62 Table 3.
The fatigue tests were interrupted and DCT imaging was conducted after certain numbers of cycles.　
In either table, the number of cycles indicated in the last column is just before the fracture of specimen.
It is obvious that the values are increased with the number of cycles, suggesting that the dislocation density increased with number of cycles.

Nevertheless achieving a high percentage of superplasticity in magnesium alloys is reported by a number of different authors.
Superplasticity in magnesium alloys can be achieved by either coarse or fine grains.
Superplastic materials generally have grain sizes in the range of 3–5µm.
Fine grained superplasticity normally requires that grain size should be homogeneously distributed on the entire surface and below 10 – 15 µm without significant growth during deformation.
Sensitiveness of SPF towards Strain Rate By observing large number of superplastic deformation data it is confirmed that the strain rate is given by: where C is a constant, E is the elastic modulus, Doexp(-Q/RT) is the appropriate diffusion coefficient, Q is the activation energy, R is the gas constant, T is the absolute temperature, b is the Burgers vector, d is the grain size and p is the grain size exponent, n is the stress exponent and σ is the stress [51].

Then, the number density of recrystallized grains can be expressed by a power law function of dislocation density evolved during cold rolling with an exponent of about 2.
An increase in the nucleation rate increases the number density of recrystallization nuclei and, therefore, results in a decrease in the recrystallized grain size.
Assuming that the size of recrystallized grains solely depends on the nucleation rate, it should be in inverse proportion to square root of the number of recrystallized nuclei per unit area, i.e., D ~ N-0.5.
Therefore, the number density of recrystallized grains in the cold rolled high-Mn steels can be expressed by a power law function of dislocation density evolved during cold rolling with an exponent of about 2, namely, N ~ r2.
In the case of site-saturated nucleation, the number density of recrystallized grains can be expressed by a power law function of dislocation density evolved during cold rolling with an exponent of about 2, i.e, N ~ r2.

The study shows that the grain protrusion height obeys an approximate normal distribution, the static effective grain density is much lower than the theoretical density, and only a small number of diamond grains are effective in the grinding process with fine diamond grinding wheel.
The commonly used diamond grain recognition method based on low pass filtering and summits counting is clearly not adequate because the number of summits significantly obtained from the low pass filtered surface depend on the selection of the cutoff wavelength.
It shows that the grain protrusion height approximately obeys a normal distribution and the mean value of the grain protrusion heights is smaller than a half of the mean grain diameters. 0 500 1000 1500 2000 2500 3000 0 100 200 300 400 500 600 μ=1.434µm σ=1.378µm Number of grains /mm2 Wheel depth of cut d/ nm 0 500 1000 1500 2000 2500 3000 0 2000 4000 6000 8000 10000 12000 14000 16000 Static effect grain density /mm2 Wheel depth of cut d/ nm Fig. 6 Distribution of the grains protrusion height Fig.7 Distribution of the static grain density The static grain density is the number of exposed grains on the wheel surface per unit area.
Therefore, the static effective grain density is much lower than the theoretical density, and only a small number of diamond grains are effective in the grinding process with fine diamond grinding wheel.
The grain protrusion height obeys an approximate normal distribution, the static effective grain density is much lower than the theoretical density, and only a small number of diamond grains are effective in the grinding process with fine diamond grinding wheel.

Statistical Aspects of Grain Coarsening in a Fine Grained Al-Sc Alloy M.
The pre-aged samples were annealed for up to 10 h at temperatures of 400, 450 and 500 °C with a limited number of experiments carried out at 550 °C.
To determine each grain size distribution, ~ 1000 grains were measured using AnalySIS Pro v3.0 software (Soft Imaging System GmbH).
Annealing at 500 °C resulted in rapid grain coarsening and a more pronounced a broadening of the grain size distribution.
A number of theoretical and empirical continuous probability distributions have been compared with experimental data in an attempt to gain a more fundamental understanding of normal subgrain/grain growth processes [2].

The orientation field variables η were chosen as η1(r, t), η2(r, t), η3(r, t)...ηp(r, t). p is the possible number in the system, and it’s considered to be 512 in the simulation, in order to show more realistic grain growth evolution.
It’s shown that the grains of abnormal growth are much larger than the matrix grains.
The local low grain boundary may be the small angle grain boundaries such as boundaries of twin grains or coherent grain boundaries.
Parsing abnormal grain growth.
Phenomenology of abnormal grain growth in systems with nonuniform grain boundary mobility.

Consider two grains joined at a grain boundary.
When deformation is carried out at temperature sufficient for grain boundary dislocation spreading, the number of dislocations dissociated at grain boundaries is very high (a planar density of dislocation 108m-1 corresponds to the volume density of dislocations 2*1017 m-2).
He supposes there are "active grain boundaries" and "passive grain boundaries".
"Active grain boundaries" are able to absorb a higher density of grain boundary dislocations than "passive grain boundaries".
Fig.5 and Fig.6 demonstrate the temperature of the drastic grain growth increases with the strip thickness because the number of grain neighbors and possible directions of stress relaxation are increased with the strip thickness too and consequently the driving force and grain boundary mobility are decreased. 1mm -20 0 20 40 60 80 100 120 140 160 180 0,0 0,2 0,4 0,6 0,8 1,0 Mean grain size, mm Time, sec Fig. 3.

Grain Refinement of Phosphorus Deoxidised Copper M.J.
Similar to grain refinement of pure Al [18], grain refinement of pure Cu requires a combination of inoculation and grain growth restriction effects to yield to a fine equiaxed grain structure [13].
Increasing the cooling rate produced a finer grain structure, but with regions having columnar grains.
Briefly, effective grain refinement requires not only the nucleating particles to be potent, efficient, sufficient in number, well dispersed, of suitable particles size and size distribution, but even solidification under high undercooling conditions.
This indicated that nano-sized MgO particles could act as potent heterogeneous nucleation sites in Cu, however there were not enough number of those particles to effectively prevent coarse grain growth. 2.