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Ssubgrain structure, partially recrystallized structure and fully recrystallized structure are evolved after different numbers of ECAP passes.
Volume fraction of true grains is relatively low (~13 pct).
Grains and (sub)grains exhibit essentially equiaxed shape.
The fraction of recrystallized grains with an average size of ~550 nm is ~76 pct.
UTS decreases under ECAP with small number of passes and attains initial value after 8 passes.

Its development, prevention or strict control are central to a surprising number of industrial processes and products so research into it has been driven by commercial as well as academic demands.
Although the cube texture develops first during primary recrystallisation, it continues to increase in strength during subsequent grain growth as smaller and less favoured grains are consumed by growth of the larger cube grains.
It seems unlikely that an OG mechanism based on ‘special’ grain boundaries is sufficient to account for the cube texture for a number of reasons.
In order to understand this it must be recognised that although the cube nuclei are very effective, they are also few in number.
Since they are few in number, a sharp texture, therefore, necessitates a large final grain size as is invariably observed.

Some grains were not smashed thoroughly, but curved and necked down, and a large of grains with fine, homogeneous and spheroids presented at 570°C (Fig.1b).
When the stirring speed was slower, the grains became larger.
When the stirring temperature was too lower, the grains grew up and got together, which made the grains coarsening and the mechanical properties reducing.
The smaller the grain size, the larger the area of grain boundary, the greater the numbers of different orientation around each grain and the plastic deformation resistance were.
The deformation could disperse into more grains.

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.

A number of particles near the surfaces of the cell wall are slug trapped during casting.
Large number of micro-pores (typically more than 1000 pores per part of a cell wall captured) is observed in the volume.
Large number of Zn- and Ti-bearing intermetallic particles is also observed in the reconstructed volume.
Grain boundary.
It seems most likely that stress singularity at free edges of grain boundaries (i.e. intersections between surface and grain boundaries) reduces apparent stress necessary for grain boundary fracture.

Moreover, with a large number of CO2 oil displacement technology used in the development of deep well and super deep well, massive costs are directed annually to alleviating and managing corrosion [3-5].
The grain size of quenched and tempered steel is generally subject to its original austenitic grain size.
Fig.7 is the graph of original austenite grain of the steel.
The smaller grain causes more area of grain boundaries and more dislocation density, so ductility and toughness of the steel can be improved.
A great number of dislocation produced because of volume difference occurred in quenching extremely cold condition.

Tensile strength under different heat input Number Heat Input /kJ·cm-1 Tensile Strength /MPa Average/MPa 1 7.5 915 946 930 4 9.6 864 884 874 5 11.5 835 805 820 6 12.0 785 815 800 7 18.0 713 707 710 Table 3.
The coarse grain zone in the heat affected zone is the zone between the two broken lines in the figure, and the lower part of the figure is the fine grain zone in the heat affected zone.
It can be seen from Fig. 4(b) that the grain size of the coarse-grained zone in the heat-affected zone is very coarse, and the austenite grain boundary is very clear.
The grain size of the coarse-grained zone can be determined by the cut line method to be about 31 μm.
It can be seen from Fig. 4(c) that the fine-grained grains in the heat-affected zone are fine, mostly equiaxed, and the microstructure is polygonal ferrite and quasi-polygonal ferrite.

An increasing number of papers were concerned with the important issue being the thermal stability of the SPD nanomaterials.
Horita Following the successful research activities in the field of nanostructured SPD-produced materials, a number of international subject-related workshops and symposia have been held after the conference.
In particular, the International Symposium on Ultrafine-Grained Materials moved its sessions on all aspects of science and technology of bulk ultrafine-grained materials produced by SPD techniques and other techniques.
Lowe (eds.): Ultrafine Grained Materials II (The Minerals, Metals and Materials Society, Warrendale, PA 2002)
Lowe (eds.): Ultrafine Grained Materials III (The Minerals, Metals and Materials Society, Warrendale, PA 2004)

However, PF models demands a large number of computer resources, so it can only simulate a few dendrites in a smaller domain.
The eutectic structures finally form at grains boundaries and the interdendrite regions.
The number of the casting cells and the chill cells is 157,558 and 133,560, respectively and the total number of macro cells including sand mould cells is 2,073,600.
As shown in Fig.5, grain size is smaller and secondary dendrite arm space is also smaller as the cooling rate increases.
These can be understood due to the fact that the increase of the cooling rate will lead to the increase of the undercooling and the number of nuclei in one certain domain, which causes the grains refining.

Line intercept method was used in order to perform grain size analysis since this method is recommended particularly for grains that are not equiaxed.
The number of grains intercepted by the line was calculated, NL.
If grains are assumed to have an ideal shape, and the same grain size, it is possible to derive an expression of d = 1.5/ NLgiving a true value for grain diameter, d, and (the diameter of an inscribed circle) from linear intercept measurements made in a random planner section.
Figure 1: Linear intercept method for grain size measurement where X marks indicated intersection between grains and line.
Grain size analysis Based on the micrograph obtained from the optical microscope, the grain sizes are measured to know the actual size of the grains formed so that the effect of aging time on grain size will be known.