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Morphology, size and number of precipitates in the both steels were examined by means of transmission electron microscopy (TEM).
The results showed that, for the experimental Nb-containing steel, the grain size was fined by the RE addtion.
Furthermore, the morphology, size and number of precipitates in the both steels were observed by means of transmission electron microscopy (TEM), to investigate the recrystallization and precipitation behaviour of the steels.
It is evidently seen that a refinement of the ferrite grain size is achieved when the RE was added in the Nb-containing steel.
Summary The comparison of the stress-strain curves and microstructure of two Nb-containg microalloy steels indicates that the grain size was refined by the RE addtion, and the deformation resistance of RE-added steel is higher than that of RE-free steel.

The experimentally measured values of stress (maximal force in particular pass divided by cross section) and microhardness are presented in Fig. 2a, as a function of the ECAP pass number.
For particular pass number two factors influence the microstructure evolution of the AA3104 alloy.
As for recrystallized grains (Fig. 7c), some preferences in selection of recrystallized grains orientation were clearly visible.
In the microstructure resulting from the ECAP processing the average size of the microstructure elements slightly decreases with the pass number.
It is well documented that for new, well-developed grains their diameter reaches 3-15 µm, independently of the applied number of passes.

Furthermore, alternative deformation mechanisms, for example grain boundary rotation [1,2] or shear stress induced grain boundary motion [3] can become the governing deformation mechanisms.
Fig 3: Change in electric resistance versus the number of cycles [6] (left) and electric resistance versus number of cycles plus the increase in stress amplitude [12] (right).
Fig. 3 shows the change in electric resistance versus the cycle number during a fatigue test.
The average grain size is below around 100 nm.
In Fig. 4 (right) some grains appear to be larger than the grains in the unloaded sample.

It makes an electromagnetic vibration box to feed grains and counts grains.
The equipment could identify and segment grains with slight color difference.
Therefore the number of kernels was obtained.
Classification of cereal grains using machine vision: IV.
Hardware-based image processing for high-speed inspection of grains.

For this later case, it has been shown that their coercivity strongly depends on grain size which is related to grain boundaries acting as pinning sites for domain walls [2, 6].
A large number of techniques have been designed, most of them being modification of existing metal forming processes, except the High Pressure Torsion (HPT) that was originally designed for geological applications [12, 13].
The bright field image exhibits an ultrafine mixture of recrystallized grains (with a low defect density) and un-recrystallized grains (with strong distortion contrasts typical of crystalline defects) appear.
Because of the lower boundary mobility (i.e. smaller growth rate), this gives rise to a higher number density of small ordered domains in the material aged at 400°C compared to 500°C.
iii) During annealing of the HPT processed alloys, ordered domains nucleate along grain boundaries and grow to fully transform un-recrystallised grains.

Six test plates with different HIs were welded respectively according to AWS A5.20/ A5.20M: 2005 standard by welding power of Lincoln powerplus-505 and numbered from 1# to 6#.Multi-layer and multi-pass welding process was adopted.
In addition, the metallographic microstructures of coarse-grain zone and fine-grain zone from 1# to 6# are shown in Fig. 4.
In addition, there are a large number of regular-shape inclusions at the bottom of dimples, and this kind of destruction form is peculiar to high toughness materials.
This means that the optimization function of fine-grained region proportion increase to toughness is less than the harm of grain coarsening and grain boundary reduces to that.
It can be seen from Fig. 4 that microstructure mainly contains polygonal ferrite (PF) and acicular ferrite (AF) with a small number of granular bainite (GB).

The individual grain orientation was measured by EBSD in a FEG-SEM.
A great number of needle-shaped δ phase distributed in the grain boundaries disappeared after solution treatment.
With the increasing of hot deformed temperature, the dynamic recrystallized grains become more uniform and the grain size increased.
The dynamic recrystallized grains are finer than the original ones.
Fig. 4 (c) shows the typical neck-structure of superalloys which there are many fine recrystallized grains around the big grains.

C in Fig.1c) is still rod-like distribution along the grain boundary, has not changed on the morphology during aging.
As shown in Fig.1d, after artificial aging, a large number of precipitates were precipitated in the crystals (shown in black and gray hue).
In this paper, on the one hand, a large number of precipitates would pin partial dislocations during aging treatment, but in the process of quenching and aging could produce a large number of newly dislocations and interfaces, which "make up" the dislocation damping performance loss caused by precipitate pinning.
Although the grain growth will occur in the aging process, but the modification additions can hinder the grain growth.
However, adding Sb can refine grains and hinder the grain growth and the reduce of equiaxed degrees during aging, which conducive to the non-elastic viscous movement of grain interface.

The grain shape and size returned to their previous states.
Compared with Fig.1a, the number of grain-boundary β decreased and the size of α increased.
The secondary α grows to link the primary α as one grain.
In the later aging period, the recrystallization of parent phase α would take place when the number of balanced β decreased, then the massive α were found.
If the number of balanced β increased, continuous β would be observed on the grain-boundary of α.

Therefore, when t the alloy undertakes deform, the movement of one crystal grain was constrained by the neighboring grains, then the stress concentration occurred at the grain boundaries, even the intercrystalline crack happened.
At the same time, it was found that if Cu-based SMA alloys' microscopic structure presented in columnar crystals or single crystal, the stress concentration at grain boundary was very low when the samples undergo shape change along the parallel direction of grain boundary.
The growths of most crystal grains were limited through the curving channels in selective growing crystallizer due to the competition between different grains; only two grains were reserved up to the middle part of the selective crystallizer, shown in Fig.1b.
This may be explained as follows: the grain boundaries are the favorite position for second-phases, precipitated phases or dispersed network phases, the presence of grain boundary makes the martensite nucleation easier, so the martensitic formation for polycrystalline that has more grain boundaries was easier than that for the single crystal without grain boundaries, therefore, the Ms for polycrystalline SMA alloy was higher than that for the single crystal.
Table 5 Number of cold-heating circulation until fracture for different SMA sample CuAlNiBe CuAlNi CuAlBe Alloy Single Crystal Poly- crystalline Single Crystal Columnar Crystal Poly- crystalline Number of Fatigue Break 487 7 465 237 45 As seen, the disadvantageous influence of the transverse grain boundaries to fatigue property alike the maximum recoverable strain experiment results.