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With the increase of shearing deformation, number of rheological ferrite increase, and become more slender.
Different finishing section of the sampling and sample numbers shown in Figure 1.
Fig.4 and Fig.6 show that the deformed ferrite grain boundaries is obvious jagged, with a large number of deformation and dislocation in the grains, and now its grain thickness takes about 200μm and the maximum grain diameter is approximately 1000μm.
At this point, the grain boundary is still showing obvious jagged, grains with a large number of deformation and dislocation.
Therefore, a number of small thin dynamic recrystallization grains germinate due to the dynamic recrystallization of the energy condition is achieved for high energy storage in the strip surface.

Particles of the powder have an irregular shape with a large number of protrusions and irregularities on the surface.
The material has a non-uniform coarse-grained structure.
The average grain size is of the order of 100-200 μm (Fig. 2a).
The average grain size is 5-20 μm.
The presence of such sections is due to the facilitated passage of the indenter through the near-surface layer with an increased number of cracks.

Most grains became much finer and coarse grains were broken into fine grains.
In addition, by increasing the number of PITS-ECAPT passes, micro-hardness of the sample was slightly increased and almost remained the same.
Most particles were contacted with each other, both the number and the size of pores were reduced, thus the compact density was slightly improved.
By increasing the number of ECAPT passes, as the powder compact was almost approached to the theoretical compacted density, the mechanical properties were increased slightly.
As the number of passes increased, larger accumulated strains were sufficient to reduce dislocations by annihilation and rearrangement within grains, so the dislocation density was nearly constant, i.e., a dynamic balance between working hardening and grain recovery was occurred.

Upon aging, precipitation of σ-phase (~5 mm) and Cr-rich M23C6 (~1 mm) along grain boundary, and nano sized Cu precipitates (~65 nm) in the grain interior were formed.
The size of Cu precipitates was relatively stable, while the fraction and number density increased with the aging temperature/time.
In the aged specimens, one may see that most of the grain boundaries and some of the matrix (grain interior) are precipitated with coarse sized (~1 mm) particles.
It can be seen in from Fig. 4a and b that the particles in size of ~300 nm and ~50 nm are observed at other grain boundaries or grain interior, or along dislocations.
The size of nano sized Cu precipitates was relatively stable, while its fraction (number density) increased with the aging temperature/time.

Fracture of ceramic materials mainly results from nucleation and expansion of large number of micro-cracks from interior.
The vibration cycle of grain is shown in Fig. 2.
has relations with the contact point of grains and workpiece.
When the grains do not contact with the workpiece, equals zero; when the grains do not depart from the workpiece, equals T1/2.
Then, the number of dynamic effective particles is (8) Fig.3 The grinding force of single particle , (9) where, lg is the length of contact arc, and ; is wheel width; K0 is a coefficient related to particle shape, dressing conditions and other; vg is the concentration of grains; d0 is the average diameter of grains.

Cooling to 460 ℃ and 400 ℃ follow by quenching, precipitates nucleated discontinuously on the grain boundaries, no precipitates was found within the grains.
The precipitates were found near the grain boundaries when quenching from 350 ℃, and precipitated uniformly within the center of the grains when quenching from 250 ℃.
The industrial processing of high strength 7050 thick plate involves a number of steps including melting, casting, homogenization, preheating, hot rolling, solution and ageing, etc.
The nominal composition of the alloy is Al-6.30Zn-2.30Mg-2.20Cu-0.11Zr-0.05Ti-0.06Si-0.12Fe (numbers indicate wt.%).
(2) Cooling to 460 ℃ and 400 ℃ follow by quenching, precipitates nucleated discontinuously on the grain boundaries, no precipitates was found within the grains

The same evolution is noticed for the Σ3 grain boundaries inside the γ phase.
For highest strained samples, the spatial resolution is not always compatible with the grain or sub-grain size.
Grain size distribution in terms of rolling reduction.
This is particularly true for the 60° grain boundary misorientations (Fig. 5b) which can be associated to the twin Σ3 grain boundary observed in the γ phase (the Σ3 percentage presented in Fig. 5b is calculated regarding the overall CSL GB number (Σ3 to Σ29)).
Indeed, Fig. 6a shows undeformed grains since the orientation remains constant inside any individual grain (Fig. 6a and 6c-top).

Figure 3 The number of recrystallized grains in Specimen A1 and A2.
Fig.3 shows the numbers of RGs formed in Specimens A1 and A2 [3,7].
In Specimen A1, the number of RGs in the a-b-c-d plane was forty-two, which was originally in the state of the surface at both deformation and annealing.
However, the number of RGs in the interiors decreased with decreasing the thickness (or being far from the surface).
But the existing of grain boundaries induced more nucleation and growth of RGs in/on the grain boundaries in the inside, because vacancies pass more easily through grain boundaries than through/in grains.

The following equation is realized up to 0.2µm grain size in the relation between yield strength σy and grain size d: σy [MPa]= 100+600×d[µm]-1/2.
In the photograph (a), it is found that dislocations nucleate at grain boundary and a fairly large number of dislocations move even though the applied stress is less than yield strength.
The grain refinement below 1µm is not so easy but ultra fine grained (UFG) iron has been fabricated by consolidation of mechanically milled iron powder.
The grain size of commercial low carbon steels is around 10µm, thus the contribution to grain refinement strengthening can be estimated at 140MPa (white arrow).
Fig. 13 schematically illustrates the grain boundary.

It was restricted in one-dimensional statistical wheel characterizations such as surface roughness of wheels and number of cutting edges.
Their centers along the tool surface are: ; .x0 and y0 are grain center position coordinates, rx and ry are random numbers equably distributed in [-0.5, 0.5] generated by the computer.
Conic Grain.
The height of grain tip for each grain can be recognized by the color of the grain.
Acknowledgements This work is supported by National Science Foundation of China (NSFC, Grant number 50975198).