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Low-temperature casting, ultrasonic vibration, and mechanical or electromagnetic stirring have been utilized to obtain fine as-cast grain structures.
As mentioned above, pulse electric current will segregate at the tips of columnar grain toward liquid phase on solid-liquid interface.
With the splitting of grain boundaries, the number of the columnar grains will increase, which makes the cellular spacing decrease, indicated clearly by comparing the morphology of the longitudinal section of the specimens with or without PED treatment in Fig.2.
Chakraborty, Effect of grain refinement on wear properties of Al and Al-7Si alloy.
Mater., Colony(Grain) size reduction in eutectic Pb-Sn castings by electroplusing. 31 (1994) 1691-1694

These alloying elements in steel can be combined with carbon, nitrogen into a carbides, nitrides, and carbo-nitrides, which dissolve at high temperatures and precipitation at low temperatures.These compounds can obstruct the growing-up of original austenite grain during heating process and inhibit grain growth after recrystallization during the rolling process.
Table 3 Actual rolling process of experiment Sample numbers Austenitic recrystallization open rolling temperature (°C) Finishing temperature (°C) 1 1080 792 2 1100 805 3 1116 850 4 1122 855 5 1120 858 6 1126 895 Mechanical test Mechanical test results are shown in table 4.
As a result, it helps to refine grain and gain good microstructure in impact and tensile properties.
According to the formula of Hall-Patch, the yield strength of steel is determined by the grain size of ferrite.
That is to say, the finer the ferrite grain size is, the higher the yield strength of steel is.

Table 2 shows the mean grain size of the experimental alloys with different Ti content.
Fig. 1 Microstructures of sand-cast alloys (the numbers are coincident with those in Table 1) Fig. 2 SEM morphologies of β phase of alloys (the numbers are coincident with those in Table 1) The distribution of Ti in β phase and matrix of sample 3 was determined by EDS analysis.
Part of Ti is also gather- ing along the grain boundaries.
This may be the reason for the grain coarsening of primary phase.
The grain coarsening is the dominant factor for the alloy.

Based on these results, a mechanism of grain growth by SIBM was suggested.
The relationship between the temper rolling reduction and average grain diameter; triangle : before temper rolling, full circles: after the final annealing following temper rolling. 0 50 100 150 200 250 0 5 10 15 20 25 30 Reduction (%) Grain Diameters (µm) Journal Title and Volume Number (to be inserted by the publisher) 3 Fig. 3 .
This texture change means that Goss grains grow more preferentially through SIBM than any other grains.
The driving force for this grain growth mechanism is usually considered to be the stored energy gradient between neighboring grains, which is known to depend also on grain orientations [1].
Journal Title and Volume Number (to be inserted by the publisher) 5 From the discussions above, D-Cube grains are thus expected to be more homogeneous than Goss ones, as it is the case for single crystals.

But in polycrystalline metals, the grains are randomly oriented and the dislocation motions in individual grains must be restricted by their neighboring grains.
The propagation of initial fatigue cracks formed in individual grains also must be arrested by their neighboring grains.
According to their considerations, the yielding strength of a polycrystalline metal is a stress to "spread out" the dislocation motion from some weak grains to their neighbouring grains and the variation of σ y with grain diameter, d, can be expressed asσ y＝σ 0+ ky d -1/2，where σ 0 is the stress resisting the movement of dislocations along the slip plane within weak grains, while the ky is a coefficient reflecting the resistance to unpin dislocations from their source in the neighbouring grains.
Actually, the ky , as well as theσ y should be higher for a weak grain located in the interior than that for a weak grain at or near the surface.
It is because that the dislocation motion in the internal grain is restricted by the neighboring grains from different sides, while that in the grain at the surface is only restricted from the internal side and is free from its surface side.

Through orthogonal test, the paper explores such factors as roasting temperature, roasting time, hydrochloric acid concentration, reaction temperature and grain size influence on the making process, and give the best operation conditions: roasting temperature is 700℃, roasting time is 1.5～3.5h, hydrochloric acid concentration is 25%～30%, reaction temperature is 120℃ and grain size is 60 mesh.
Through researching, we elected five influencing factors, they are roasting temperature, roasting time, hydrochloric acid concentration, reaction temperature and grain size.
Table 3 L16（45）orthogonal array and test result Test Number Roasting Temperature/℃ Roasting Time/ h Hydrochloric Acid Concentration /% Reaction Temperature/℃ Grain Size /M Test Result Leaching Rate /% A B C D E 1 1 1 1 1 1 43.3 2 1 2 2 2 2 44.9 3 1 3 3 3 3 48.1 4 1 4 4 4 4 51.8 5 2 1 2 3 4 47.5 6 2 2 1 4 3 48.9 7 2 3 4 1 2 51.4 8 2 4 3 2 1 56.3 9 3 1 3 4 2 68.2 10 3 2 4 3 1 73.1 11 3 3 1 2 4 59.1 12 3 4 2 1 3 62.7 13 4 1 4 2 3 49.2 14 4 2 3 1 4 42.1 15 4 3 2 4 1 45.8 16 4 4 1 3 2 43.9 K1 188.1 208.2 195.2 199.5 218.7 836.3 52.27 K2 204.1 212.7 200.9 209.5 208.4 K3 263.2 204.4 214.7 212.6 208.9 K4 181.0 214.7 225.5 214.7 200.5 47.03 52.05 48.80 49.88 56.68 51.03 53.18 50.23 52.38 52.10 65.80 51.10 53.68 53.15 52.23 45.25 53.68 56.38 53.68 50.13 R 20.55 2.58 7.58 3.80 6.55 Through variance analysis, we found the big and small order of every factors, they are Roasting Temperature (A) > Hydrochloric Acid Concentration (C) > Grain Size (E)> Reaction Temperature (D) > Roasting Time (B)
The best experimental design is A3B4C4D4E1, that is roasting temperature is 700℃, roasting time is 3.5h, hydrochloric acid concentration is 30%, reaction temperature is 130℃ and grain size is 60 mesh.
Table 4 Three better test condition Test Number Roasting Temperature/℃ Roasting Time/ h Hydrochloric Acid Concentration /% Reaction Temperature/℃ Grain Size /M 9 700 0.5 25 130 80 10 700 1.5 30 110 60 12 700 3.5 20 70 100 According to above analysis, energy consumption, costing and so on, we selected the best test condition is roasting temperature is 700℃, roasting time is 1.5～3.5h, hydrochloric acid concentration is 25%～30%, reaction temperature is 130℃ and grain size is 60 mesh.

It is shown that the basic mechanisms of initiation are very similar from a physical point of view: PSB and Grain boundary cracking.
In this case, the cyclic plastic deformation is related to the stress concentration around a defect: inclusion, porosity, super grain, etc...
At low deformation, the plasticity can appear only if the grain orientation and the grain size are in agreement with the dislocations sliding.
However, the number of PSB increases with the number of cycles and no experiment exists to prove that some PSB cannot form at 1010 cycles or more.
These slip bands are multiplied or grown in the same grain due to following cycles.

Grain size distribution, hardness and temperature profiles in the welded zones were determined in order to obtain the relationship between the grain structure and the hardness profile in these regions.
In each alloy, the average grain size in the weld nuggets was identical.
The Vickers hardness numbers of the welded zones in all specimens were measured on a cross-section perpendicular to the welding direction using a Vickers indenter using a 100 gf load applied for 15 seconds.
In all specimens, the average grain size in the weld nuggets was the same.
Microhardness numbers of joints across the mid-sections; (a) 2024, and (b) 5083 alloys.

The grain shape and size returned to their previous states.
Compared with Fig.1a, the number of grain-boundary β decreased and the size of α increased.
The secondary α grows to link the primary α as one grain.
In the later aging period, the recrystallization of parent phase α would take place when the number of balanced β decreased, then the massive α were found.
If the number of balanced β increased, continuous β would be observed on the grain-boundary of α.

Introduction During the fabrication processes of integrated circuits, the interconnect materials are subject to a number of thermal cycles.
To date, there have been many studies of the various factors affecting hillock formation, such as the grain size [1], grain orientation [2] and grain-boundary characteristics [2].
Thus, the most plausible site for hillock nucleation might be the grain-boundary triple points.
The number of these points is proportional to one over the square of the grain size (d -2) [1].
The hillock density decreases with increasing film thickness, because the number of plausible nucleation sites for hillock formation, such as grain-boundary triple points, decreases.