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The numbers on the micrographs indicate the lattice curvatures between the pointed micro volumes.
Also, the number of internal dislocation in grain interiors remains almost unchanged upon the treatment.
The numbers indicate the lattice curvatures within the grains.
The grain coarsening follows normal grain growth behavior with a power low function of annealing time.
Thus, the ultrafine grained microstructures evolved under severe deformation are susceptible to fast grain boundary recovery upon subsequent heating.

Based on the results of the thermodynamic analysis of a number of experimental data, and in the light of the Kaibyshev-Valiev discovery, the possibility of periodic formation of a liquid-like state in the nanoregions of extremely "non-equilibrium" grain boundaries and in other structural defect regions in metallic polycrystals during superplastic deformation and intense plastic deformation is considered.
It should be noted that according to a number of known data (e.g., those in [13]), the structure of high-angle grain boundaries in metallic materials has a heterogeneous character and includes even in the “equilibrium” state I (GB1) about 1 % of excess free volume [14].
Hence, the “GB sliding” mechanisms can be related to the mutual turning (cranking) of grains by means of some slippage along grain boundaries (GB3), which are in the liquid-like state III.
The “GB sliding” mechanisms can be related to the mutual turning (cranking) of grains during SSPD by means of some slippage along grain boundaries (GB3), which are in the liquid-like state III.
Diploma number 339, 1988.

The results show that as number of ECAP passes increase, the applied strain accumulated in the samples also increases and the grains change from equiaxed to elongated structure.
No Number of ECAP pass (N) Strain (ε) Average grain size, µm 1. 0 0 48.2 2. 1 0.6667 36.3 3. 2 1.3334 33.5 4. 3 2.0001 30.2 The stored energy due to ECAP process indicated by strain (ε) increased with number of ECAP pass.
The hardness of the specimens increased with the increasing number of ECAP passes.
Hardness as a function of number of ECAP passes Conclusions 1.
ECAP process make the grains elongated and smaller compared to the grains of raw material. 2.

By using new intermetallic compound grain refiners, chemical grain refinement casting technology was carried out to refine K4169 superalloy.
The results show that the grain morphology has been transformed from dendrite to granulation, the average principal axis length of the primary dendrites has been shorted and the segregation ratios of main alloy elements mitigate with the decrease of grain size in fine-grained castings, which indicates the remarkable effects of grain refinement.
of Microstructure Evolution In the past, the researches on the processing of superalloy using chemical grain refinement casting were mainly depended on test methods.It was through a large number of experiments to study the relationships between the solicitation process and the grain structure.
Conclusion The grain structure obtained by grain refining casting had a big decrease on its principal axis length of the primary dendrites, while the span of the secondary dendrites did not change much; The grain refining process went with the process of the grain morphology transformed from dendrite to granulation.
Mondolf, Grain Refinement in the Casting of Nonferrous Alloys, in “Grain Refinement in Casting and Welds”, Eds.

CDRX is a process of dislocations continuing to gather to the small-angle grain boundaries, becoming to large-angle grain boundaries, and then forming fine grains during the deformation of metal [4].
However, the grain refinement in the piston pin holes is more obvious, the grain is refined to 13 μm and the refining rate is about 67.5%(shown in Fig.5a, 5b and 5c).This is attributed to the longitudinal extrusion, during which the deformation of the piston skirt processed by backward extrusion is intense, the severe deformation energy leads to a large number of tangly dislocations appearing in the piston skirt, which arises a big stress field between these dislocations.
Then these dislocations interact and rearrange to form a subgrain structure, and the subboundaries furtherly evolve into small-angle grain boundaries and large-angle grain boundaries, thus causing CDRX and refining grain.
The grain refinement of piston pin holes is more obvious, the grain is refined to 13 μm and the refining rate is about 67.5%
Application status of hot deformation metal grain size predicted[J].

Grain maps of this martensite were initially assembled from the data sets with a grain boundary tolerance of 3-5 degrees.
Grain growth will continue at the hold temperature.
The grain growth of austenite is controlled by the grain boundary migration.
The driving force for the grain growth is grain boundary energy reduction and the mechanism related to triple point force balance and grain boundary curvature [9] .
In addition, an empirical equation describing the effect of heating rate on AC1 has been established. 5- Acknowledgment The authors are grateful for financial support from the European Commission under grant number 675715 – MIMESIS – H2020-MSCA-ITN-2015, which is a part of the Marie Sklodowska-Curie Innovative Training Networks European Industrial Doctorate programme.

Currently, adding refiner is the main method for refining aluminum grains.
When the amount of B increases to 0.04% in sample (c), it has a large number of central equiaxed grain and grain size becomes small; With the content of B increasing, the samples with boron content of 0.06%, respectively (d), 0.08% (e) and 0.10% (f) have been stably presented fine macrostructure.
A uniform and fine grain structure when the content of B runs up to 0.06% or more
Senterner, The role of boron in the grain refinement of aluminum with titanium.
Eidhed, Fading mechanism of grain refinement of aluminum-silicon alloy with Al-Ti-B grain refiners, Mater.

In this paper, it is proposed to highlight consequences of chaining DDRX and PDRX mean field models on average grain size and grain size distribution.
A mean field description of the grain structure is used: a spherical grain interacts with an equivalent homogeneous matrix whose properties are the average properties of all the grains.
Several mechanisms contribute to the evolution of the grain properties: (i) Grain Boundary Migration.
(iii) Nucleation of New Grains.
Sketch describing the relation between the number of grains within a given diameter range and the time elapsed Acknowledgements G.

Lattice strains of several hkl planes of austenite respective ferrite were mapped as a function of sample direction at a number of load levels during loading into the plastic regime and unloading.
Residual stresses depending on the grain-orientation and phase have been found after unloading.
At about -550 MPa, the α-211 grain subset yields, followed by the α-200 at about -600 MPa.
Grain-orientation-dependent residual stresses have been induced in the steel.
Residual stresses depending on the grain-orientation and phase have been found after unloading.

The grain refinement is a constant process covering formation of low-angle grain boundaries, gradual increase in disorientation as an effect of dislocation accumulation and eventually formation of high-angle grain boundaries.
The microstructure remain grained with grain size on the same level (average grain diameter about 40 μm).
Grains size distribution for such case is shown in fig. 8.
After RCS processing number of low angle grain boundaries increased significantly.
Acknowledgment This work was supported by the European Union, Structural Funds Operational Program Innovative Economy - Project Number POIG 01.01.02-00-015/09 References [1] Yuntian T.