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By controlling the number and size of large particles, the nucleation sites for recrystallization can be controlled and by controlling the number of dispersoids and elements in solid solution, the nucleation and growth can be decelerated.
This will in turn lead to dissolution of the dispersoids close to the grain boundaries.
In the smallest grains (given by the sample-section) no dispersoids were found and in the larger grains the dispersoid size and number density varied with the position in the grain.
In addition, a small number of Si-particles were found in this alloy.
To further investigate this, the number density of dispersoids was measured in the TEM in samples heated to 500 o C and then quenched.

According to optical and TEM microscopy the average grain size was refined considerably from ~80 μm to ~1 μm.
It is well known that, severe plastic deformation (SPD) process introduces large number of GBs in materials [7, 8].
Equal-axial coarse grains (CG) dominate the morphology of microstructure.
For multiple ECAP processing, a total number of eight passes process has been applied on the CP tungsten rod with a diameter of 15 mm.
The microstructure of multiple ECAP tungsten is not homogeneous, there’re equal-axial and elongated grains distributed in the field.

Average grain size and mechanical properties.
(a) At N= 2.0×103 cycles, Crack 1 was formed in Grain I.
Schmid factors of the basal slip system of each grain are indicated in Fig. 5, where the number of cycles, N, of each figure is the same as that of Fig. 4, and crack profiles were drawn by black lines.
Also, size of crack-initiated grains is much larger than the average grain size.
Acknowledgement Support of this work through a Grant-in-Aid for Scientific Research (C) from Japan Society for the Promotion of Science under proposal number 18K03837 (Head investigator: Professor Y.

In this case, a section or a projected image is enough provided that the number of objects containing by the section is enough statistically.
Similarly to it the PP quantity (point relation) can be derived as PP = P /P, where the P� in the numerator means the number of points being in the microstructure shape, while the P in the denominator represents the total number of points of the investigated sample.
the number of steps.
The histogram of porous grain can be seen in the Fig. 10, while the histogram of compact grain can be seen in Fig. 11.
PVC-grains of different compactness.

Fig. 2c demonstrates the distribution of grain boundary misorientations, by which the average grain boundary angle and the fraction of high angle grain boundary (≥15 deg) were measured.
However, the strip-like carbide may play a dominant function, because the number of strip-like carbide is obviously more than that of spherical carbide in each tempered steels.
The residual carbides pin and drag grain boundaries, by which prevent grain growth.
Therefore, it can not be seen that the number of carbide increases obviously as improving V content.
Summary (1) The prior austenite grain is refined owing to different types of carbide pinning grain boundary during austenitization.

The final grain size and recrystallization texture depend on many factors including thermomechanical history.
The area and the size of the recrystallized grains generally increase as the annealing time increases.
It is observed that some deformed grains are completely consumed by new grains, whereas other deformed grains are partially replaced by new grains .Specimen 1 and specimen 2, 22 seconds annealing recrystallization did not occur, When annealing 24 seconds the specimen 2 had the approximately 35% deformation band to form the recrystallization, but the specimen 1 basic has not formed the recrystallization.
Annealing process conditions in the specimens are complete recrystallization and grain growth occurred.
These differences may be related to the number of shear bands formed in the cold rolled state, In the equiaxial-grained specimen, Gauss texture and rotateds the Gauss texture of the with the certain deviation are significantly strengthened

The paper presents the abrasive grain motion equations, removal rate model,grinding force model and grinding force ratio model.According to the grinding force model, the grinding force will decrease as the spindle speed, vibration amplitude and vibration frequency increase.
The kinematics analysis of UAG Fig. 1 The motion model of axial ultrasonic vibration assisted grinding [2] As shown in Fig. 1, there arethree kinds of grain motion such as grinding wheel rotational circular motion,grinding wheel feed movement and the simple harmonic oscillation.Based on the UAG kinematics analysis, establish the single abrasive grain trajectory model.
x=(vw+vs)t1 (1) y=Asin(2πft1+Ø0) (2) z =R-Rcosωt1 (3) Wherevs is grinding wheel speed,t1 is grinding time of single grain, ω is grinding wheel angular velocity, vw is feed rate,f is ultrasonic frequency, R is grinding wheel radius, Ø0 is ultrasonic vibration initial phase, A is ultrasonic amplitude.According to the single abrasive grain trajectory model can get the grain trajectory curve: Fig. 2 (a) (b) (a) Grain trajectory in single rotation period of grinding wheel (b) The trajectory of single grain contact with the workpiece Assume the ultrasonic vibration initial phaseØ0=0, the trajectory length of single grain contact with material in single rotation period can be defined as follow: (4) UAG material removal rate modeling Fig. 3 Abrasive grain pressed depth Fig.3 shows pressed depth of single abrasive grain.
The depth of grain pressed into the material is ag, cone apex angle is θ, and the grain trajectory groove width Ø can be deduced as follow: (5) The cross sectional area of grain pressed into the material can be found: (6) Single grain material removal volume is defined as follow: (7) Assume that the distributing density of the dynamic grain on the wheel surface is Nds，the grain number through the dynamic grinding area in unit time is N=Ndsbvs，Whole material removal for volume in unit time can be defined as follow: (8) The average chip cross section area in AUAG is: (9) Average grain pressed depth is: (10) The grinding force modeling of UAG Fig.4 Grinding force distribution of single grain The grinding force produced by chip deformation As Fig.4 shows, agis grain average cutting depth.There is an angle Øbetweengrinding direction and OAB .The area of OAB is ds.Grinding forcedF is vertical to the conical surface
Thenwe can deduce: (12) ρis cone length, can be found: (13) Put (13) into (12),can be obtained: (14) Substitute (14) into (11),can be found: ; (15) The grinding forceof single grain: ; (16) The total grinding force: ;

The precipitation occurs at not only grain boundaries but also twin grain boundaries in the experimental steel.
The grain boundaries are clean, straight and thin.
This can be considered as follows: Large numbers of defects exist in material after cold deformation.
Cold deformation may cause dislocation pile-up at grain boundaries, and increase the distortion energy of grain boundaries, which can nucleate σ phase at grain boundaries and defect microstructures (deformation twin and slip band) accelerate the precipitation of σ phase inside grain.
The precipitation occurs at not only grain boundaries but also twin grain boundaries in cold-deformed Fe-18Cr-12Mn-0.48N steel

That Allows MH grain nucleation rate is less than the growth rate, Larger MH grain generated in system.
At this time, the nucleation rate is greater than the growth rate, a large number of fine grain were generated, it lead to the grain reunion in the solution and make the size bigger.
With higher temperature, ion activity increase further, a large number of fine grains were generated in the solution, lead to a serious of particle aggregation occurred.
Speed of NaOH precipitation reaction is quickly, generate a large number of slow growth microcrystalline in short time.
Long carbon chains of SDS easily adsorbed on MH surface, thus prevented the bulky hydrated Mg2+ ions enter grain zone to grow.

Fig. 2(b) indicates that the large <111> and <001> grains involve sub-grain boundaries, and some <001> grains have crytallographic orientations nearly identical to those of the neighboring <111> grains in the directions normal to extrusion.
However, the grain size and the fraction of <111> grains increased by the re-solution treatments, as shown in Table 3.
The average grain size and the fraction of <111> grains.
In T7 temper, the coarsening of η precipitates (MgZn2) occurs in grains as well as along grain boundaries, which is associated with the widening of precipitate free zones (PFZ) along grain boundaries [5].
The curves in this figure are drawn by using a phenomenological equation, sa = sao + k{(Nf/Nfo)-m - 1}, where sa and Nf are the stress amplitude and the number of cycles to failure, respectively, Nfo is a reference number of cycles (=107 cycles in the present analysis), sao is the fatigue strength at Nfo, and k and m are constants [3].