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Additionally, solutes impose a drag on moving grain boundaries.
Journal Title and Volume Number (to be inserted by the publisher) 3 Another purpose of intermediate annealing processes is to control grain size and texture of the final microstructure, that is at the end of all processing, with the purpose of achieving optimum formability and surface quality after forming in a customer process.
In fact, the latter is an important tool in controlling the Journal Title and Volume Number (to be inserted by the publisher) 7 degree of recrystallization during industrial processing.
The data show that at the onset of recrystallization a large number of soluble phases are precipitated, interfering with the on-going recrystallization process.
On Recrystallization and Grain Growth, Eds.

The HPT strain degree was varied by the number of rotations or turns (n) from 1 to 7.
The transformation yield stress for martensitic transformation (sm) of the nanocrystalline alloy with a grain size of 20 nm is about 450 MPa (Fig. 1b), which is three times higher than sm in the initial coarse-grained state (sm » 160 MPa).
It is clearly obvious that sm value increases as grain size decreases.
Microstructure of the Ti49.8Ni50.2 alloy after ECAP 4500C n= 8 (a) and stress-strain curves (b) in the initial state and after ECAP with the same number of passes After ECAP processing ductility decreases, however, remains sufficiently high – about 25%.
The maximum recovery stress σrmax increases with the increase of the number of ECAP passes, achieving 1080 MPa after 8 passes and 1120 MPa after 12 passes, which exceeds the level of the initial condition (480 MPa) by more than 2 times [4].

This difference in groove numbers and maximum groove depths relatively corresponds to the difference in grain density and ha values shown in Fig. 4 and 5, respectively.
LGS also shows more aligned grain distribution with respect to z, compared to MGS. 500 µm Max. 35 µm 50 µm Max. 50 µm (b) MGS (a) LGS Ground depth, z Ground material width, r The number of grooves：9+1.5 mm-1 The number of grooves：6+0.5 mm-1 Figure 6.
The difference in ground groove numbers corresponds to the difference in grain density between LGS and MGS.
Thus, the number of ground grooves is calculated as Nge(z) x L, assuming all the effective grains on a GS surface form continuous groove lines.
As it is mentioned in profiles in Fig. 6, LGS forms higher number of grooves and more aligned grooves on a ground material surface than MGS.

Ultrafine-Grain Structures produced by Severe Deformation Processing P.
Keywords: Severe deformation, Aluminium alloys, Ultrafine grains, EBSD.
Introduction Ultra-fine grained materials offer significant advantages in terms of high strain rate superplasticity and improved mechanical properties, compared to materials with conventional grain sizes [1].
However, in practice, the batch nature of the process, the high number of cycles required to develop a fine grain microstructure, and the forces required to deform large diameter billets, mean that the process is likely to remain laboratory-based.
For example, fine dispersoids required for grain size stability during superplastic forming inhibit grain refinem ent.

INTRODUCTION: The feasibility of producing ultra fine grain size microstructures in metallic materials via equal channel angular extrusion (ECAE) has been demonstrated in a number of pure metals and alloys, [1-4]. .
This deformation results in little to no dimensional changes of the sample, therefore an unlimited number of passes is possible, resulting in production of large strains in the material Deformation with such large strains can be utilized to produce grain refinement by one of several methods viz., grain fragmentation and rotation, dynamic recrystallization, or deformation followed by static recrystallization.
The sample was subjected to two and four extrusion passes with a 90° rotation and a 180° flip between passes A number of samples were subjected to post ECAE annealing in the alpha beta field to produce grain refinement by static recovery and recrystalization.
Langdon, The Process of Grain Refinement in EqualChannel Angular Pressing.
Effect of Route, Number of Passes and Initial Texture.

In contrast, in 3rd and 4th passes of rolling new grains nucleated at grain boundaries, due to low grain size of the alloy.
Because of their low formability due to the limited number of available slip system, the forming and shaping of wrought magnesium alloys at room temperature has been highly restricted.
Although the average grain size increased during heating the specimen, the grain size of the alloy reduced with the increase of the number of rolling passes.
In the beginning of the hot rolling process, mechanical twinning occurs easily inside the grains, because of large grain size.
In last two samples, mostly new grains nucleated at primary grain boundaries forming equiaxed grains.

There are a fine-grain zone and coarse-grain zone in the cross section during milling.
Equiaxed grain occupied most.
The grain size gradually grew with the engineering strain from 30% to 90%, mixed equiaxed grain and deformed grain.
A small number of twins were also observed at the outlet.
Another difference is that deformation twins often contain large number of sub grain boundaries, but the annealing twins contains no distortion.

Microstructure of FeAl38 alloy after deformation e = 0.25 at temperature T = 1150/1000°C with a rate of 0.1 s-1, number of deformation cycles 4/4 (a) fine grains after deformation, (b) nuclei of recrystallization an migration of high angle boundaries.
The distribution of grain sizes a) and boundary misorientations as measured by linear intercept (b) after deformation at temperature T=1150/900°C with a rate of 0.1 s-1, number of deformation cycles 4/12.
Substructure of FeAl38 alloy after deformation e = 0.4 at temperature 1150/900°C, number of deformation cycles 4/12 a) subgrains with dislocations b) fine subgrains and nuclei of recrystallization Summary The applied methods of cumulative deformation on Max Strain simulator show possibility of intensive grain size reduction.
Suitable number of deformations (8, 16) and temperature of the process (1150°C /1000°C, 1150°C /900°C) enable to obtain substantial grain size reduction of the tested material.
Average grain diameter of d = 7.3 µm was obtained, that is 15 times the effect of grain size reduction.

That is because the hard phase grains are tiny.
It can be found from the Fig. that the number of hard phase peering pits decreases.
Appropriate Carbon content refines grains, it makes the rim phase become thinner.
The number of binder phases among the rim phases also decrease along with the increase in carbon contents.
When the Carbon content is 0.8%, the grains of the cements are tiny and the distribution of binder phases among the rim phases is uniform; when the Carbon content is 1.2% the grains are the smallest and the number of the binding phases is at least.

Oswald ripening occurs for grains surrounded by recrystallized grains.
Giving the size distribution p(r), the total number of candidate subgrain is then can be given as: ∫ ∞ ⋅= acr s drrpNN )( (3) where Ns is the initial site number related to dislocation density and original austenite grain size.
The final grain size of recrystallized structure depends on both grain growth and coarsening.
In order to calculate them simultaneously, recrystallized grains are treated as two groups -- surface grains and interior grains.
The grain growing rate that combined growth and coarsening is: ) ( 3 2 3 2 dt dN NR dt dNr dt dR N dt dR NR dt dR rec rec rec rec c surf surf inte inte rec rec +⋅ ⋅+      ⋅+⋅⋅ = (5) where Nsurf and Ninte are number of surface grains and interior grains respectively.