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However, until now only a limited number of studies [7] have been focused on FSW of die casting aluminum alloys.
Because the new grains are shattered by probe before growing up, the grains' size in NZ is very small.
These grains are very trivial, causing microhardness to maintain at a high level.
In HAZ, affected by welding thermal cycle only, the grains are coarse, resulting in the lowest hardness.
Conclusions (1) Trivial equiaxed grains form in the NZ of FSW joints, TMAZ structure has a greater degree of bending deformation and HAZ has slightly grain coarsening phenomenon

Grain coarsening is a major problem in ferritic stainless steels and such grain coarsening causes lower toughness.
To minimize grain growth, weld heat input should be minimized.
Ferrite grain size and carbide precipitation affect the hardness of the FSS.
The HTHAZ exhibited ferritic microstructure with excessive grain coarsening.
Acknowledgements This work is supported by Abant Izzet Baysal University under Contract Number AIBU, BAP. 2016.09.05.1048.

When the grain boundary sliding is the dominant deformation mechanism, the alloy with fine grains is correspond to lower flow stress than the alloy with coarse grains.
The reason for this is that compared with the alloy with coarse grains, the grain boundary density of the alloy with fine grains greatly increases so that the deformation can be implemented easily.
Hence, the alloy with fine grains is correspond to higher flow stress than the alloy with coarse grains.
On the fracture surface of UDC casting billet, the defects are alleviated and the number of dimple increases.
Bisadi, Effects of initial grain size on hot deformation behavior of commercial pure aluminum, J.

With USV process, the average grain size of primary Si in the alloys could be refined to 21~24μm, whether with or without P modification.
The microstructures of as-cast Al-25Si-xFe-yMn alloy (y/x=0.625) also contained a large number of dendritic α-Al15(Fe,Mn)3Si2 phase [6].
And the effect of USV results in the precipitation of a large number of fine δ particles.
At the same time, the dispersive distribution of the fine δ particles in the matrix of the A1 and A2 alloys with USV treatment can also prevent grain boundary sliding.
They mainly exist as particle-like δ-Al4(Fe,Mn)Si2 phase with average grain size of about 18μm, and only a small amount of β-Al5(Fe,Mn)Si phase is remained.

After annealing at 3.03×105 Pa, the grain size became larger and oxygen content in the annealed films increased.
The crystalline quality and the grain size of the annealed films will be changed.
The variation of the grain size of ZnO crystallites with annealing pressure is also given in Table 1.
The grain size shows an increase while the annealing pressure increases.
The electron concentration (n-type) of Sample 1 is three orders of magnitude larger than that of the as-grown MgZnO films that is attributed to the better crystalline quality of the annealed films and larger number of VO in the films.

There has been a large number of studies focusing on bridging the microstructure and macroscopic mechanical properties by both experimental and numerical methods.
Grain reconstruction and analysis have been carried out by MATLAB/MTEX toolbox [11]. 15º misorientation threshold was used for the grain reconstruction.
The investigated material has an average grain size of 16 μm and mean grain shape aspect ratio of 1:0.681:0.662.
During the RVE generation process, the most representative and effective factors are element size and number, which are corresponding to the final RVE size.
The finally optimized RVE model is shown in Fig. 2, which contains 3165 Al grains.

Moreover, the main deformation mechanism was twining at strain of 0.08 for the as-solution alloy; with the increase of the strain, dynamic recrystallization (DRX) grains appeared at original grains and twins boundaries.
As reported, the nano-scale I-phase is precipitated within matrix and at grain boundaries which hindered the DRX grains growth during hot deformation[13-15].
However, the main deformation mechanism was also twining and the number of twins increased, as shown in Fig. 5b, and the stress-strain curve also showed the hardening state (as suggested by Fig. 4).
As the strain continued to increase, it was found that the DRX grains in almost grain boundaries and the grains, especially, at the strain of 0.6.
A large number of twins formed in as-compression Mg-4.5Zn-0.75Er alloy below the strain of 0.15.

The primary α plates form predominantly on β grain boundaries, whereas the bainitic α plates nucleate both at grain boundaries and intragranularly.
These α plates are generally irregularly shaped plates, which nucleate predominantly at the prior β grain boundaries.
The bainitic α plates are relatively perfect thin plates, which nucleate both at grain boundaries and intragranularly.
It is seen that the bainitic α plates have nucleated both at former β grain boundaries and intragranularly.
Based on a number of micrographs it is found that the thickness of bainitic α plates is in the range of 0.2 - 1 μm.

It has been shown that the anodes have uniform surface composition, and the surface density of the anodes were increased as the sintering temperature increased, Some active elements were crystallization grains at the surface of the anode when sintering temperature ³ 500°C.
Compared with the traditional anode, the oxide anode prepared by Pechini method has the characteristics of homogeneous structure and grain size.
Oxidation technology on coating quality is very important, sintering temperature and sintering time has a great impact on the coating structure, such as the grain size.
The sintering temperatures were respectively designated as 400°C, 500°C, 600°C, so the sample numbers were designated as a, b, c in turn.
The larger the area surrounded by curve, the more number of activity points on the surface.

Based on a large number of experiments, Mn should selest in the range of 1.5%～3.0%
(2)In order to give full play to the strengthening, toughness of the phase boundary, the grain boundary and sub-grain boundary of microstructure, the precipitation of carbon in steel from the supercooled A phase cannot be low intensity proeutectoid F, and should be high strength, high toughness of BF, and the final microstructure should be mechanical mixture (BF+A).
Supercooled A of steel should carry on the phase transition in the middle and lower temperature period with medium temperature on bainite formation and should add trace elements V, Nb which could refine the grain size .
The three ball grind out a number of plane on the grinding wheel respectively, the values of hardness are shown in table 2.
The characteristics of the granular bainite is a number of granular island which are a carbon-rich austenite at high temperature zone inside the large block or acicular ferrite.