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The sample number and heat treatment process seen Table 1. 2.
A large number of ferrite existed in the sample quenched at lower temperature, and part of them was independent existence as block shaped (Fig. 1(a)).
The austenite growth is mainly through the grain boundary migration, but the austenite has been split by ferrite which existed in the sub-temperature quenched microstructure, and impeded inhibiting austenite grain boundary migration.
At the same time, the lower quenching temperature was not benefit to atomic diffusion, so grain boundary migration was slow, the austenite grain growth was hindered [7].
(2) The austenite grain size of 35CrMo steel can be refined by sub-temperature quenching

The average grain size slightly increased with the increase of ZrO2.
The grain morphology and size were directly imaged, using scanning electron microscopy [SEM] and the average grain size was determined by using a mean linear intercept method.
It was found that the PT powders indexed in a tetragonal structure and thesematched with JCPDS file number 70-0446.
The microstructure reveals that the grains are rectangular in shape with different grain sizes.
The grain sizes of PT samples with various the amount of ZrO2 doping.

The Widmanstätten microstructure and coarse grains were observed in the overheated zone.
Table 1 shows technological parameters and specimens numbering.
Table 1 Technological parameters and specimens numbering.
Ferritic and pearlitic grains with different sizes were found in the partially-recrystallized zone.
Penetrator, coarser grains and the higher grade of Widmanstätten microstructure will produce if the power input increases above the value.

Fig. 4 shows the diagrams obtained on wheat grain with a moisture content of 11,5% at Sm=0,13 mm.
Load-discharge diagrams for static compression of wheat grain.
Some of the grains that were not impacted were collected in the accumulator and excluded from the experiment.
For wheat grain: on the copra Qk=1,3; on the impact stand Qu=1,45.
For the grain, the value Qu is not reliable due to difficulties in determining the residual deformation from the contact spot left on the grain after the impact.

Refining of prior austenite grain through repeated quenching is a procedure that can be used to enhance the material’s strength.
A comparison of the prior austenite grain sizes refinement achieved through repeated quenching is shown in Figure 6.
In the Q1T1 specimens, the grain size was approximately 10-25μm (Figure 6(a)), while in Q3T1, it varied from 5μm to 10μm (Figure 6(b)).
Figure 10 shows the modified S-N curve graph relating the stress amplitudes at the crack origin depths to the number of cycles.
(a) The fracture surface in Q1T1 (b) The core of the fractured surface in Q1T1 (c) The fracture surface in Q3T1 (d) The core of the fractured surface in Q3T1 Fig. 9 Fisheye fracture of the Q1T1 and Q3T1 samples: (a), (b) Q1T1, sa = 1140MPa, number of cycles to failure = 630442; (c), (d) Q3T1, sa = 1140MPa, number of cycles to failure = 4795215.

Refining the prior austenite grain size through repeated heating is a process commonly used to enhance the material’s strength.
A comparison of the prior austenite grain sizes refinement achieved through repeated quenching is shown in Figure 6.
The number of crack origins of Al2O3 was four, and that of TiN is one in the Q1T1 samples.
Figure 10 shows the modified S-N diagram based on the stress amplitudes at the crack origin depths to the number of cycles.
Q1T1, sa = 1200MPa Number of cycles =955735 Q3T1, sa = 1200MPa Number of cycles = 1349531 (a) (b) Fig. 8 Fisheye fracture in specimens Q1T1 and Q3T1 Fig. 9 S-N diagram with kinds of crack origin.

The experiment result showed that formation of coarseferrite grain in as-rolled state leads to lower impact toughness.
Fig.3 Impact fracture of as-rolled plate Fig.4 Impact fracture of normalizing plate Fig.5 Impact fracture of normalizing-tempering plate 3.3 Microstructure of different state plates Microstructure of as-rolled plate was bainite, ferrite and pearlite, its average ferrite grain size was 24μm, as was showed in fig. 6a.Microstructure of normalizing plate was ferrite, bainite and pearlite, its average ferrite grain size was 13-15μm,as was showed in fig. 6b.Microstucture ofnormalizing-tempering plate was ferrite, bainite and pearlite, its average ferrite grain size was 13μm,as was showed in fig. 6c.
V, Nb and Mo can be further precipitated in the form of carbide when it is processed by tempering treatment, and therefore it enhances the precipitation strengthening effect. 4.1 Effect of normalizing on microstructure and mechanical properties of as-rolled plate Large number of dislocations were formed in the hot rolling process，dislocationstrengtheningwas machenism of as-rolled plate with higher tensile strength.
Deformed austenite grains were continuiously recovered and recrystallized, but if the finishing rolling temperature was too high, recrystallized austenite grain will continue to grow, transformation of austenite after cooling would be F+P,F+B or mixture of F+B+P, coarse ferrite grain would be formed ,as was showed in figure 6a.coarse ferrite grain made low temperature toughness be bad.
In the process of normalizing, coarse ferrite grain was transferred to uniform refined ferrite, as was showed in figure 6b.Normalizing eliminated distortion of hot rolling process and high density dislocation, therefore, the strength of normalizing plate was decreased but its percentage of elongation was improved to some extent.

A coarse grained Al matrix was also used for comparison reasons.
As seen, the yield strength of the nanostructured Al is significantly higher than that for the coarse grained Al.
As seen, the yield strength of the nanostructured Al with grain size of 48 nm is approximately four times higher that of the coarse grained Al.
In contrast, the milled composite can be characterized by a much finer grained matrix structure.
In nanocrystalline materials, due to small size of the grains, dislocations cannot multiply in large numbers and the materials are expected to have an intrinsically low ability to store dislocations and hence, insignificant strain hardening [9].

The very fine elongated grains and fragmented grains along with precipitates were also observed after four ECAP passes.
The misorientation angle of the grains with respect to extrusion axis decreases as the number of passes increases which indicates tendency of texturing [10].
As the number of passes increases the density values increases.
The values are listed in table 3, as the number of passes increases the hardness value increases.
So as the number of passes increase the better consolidation obtained due to good densification.

Secondly, there are some small grains in the samples sintered for 15min and 20min, and the number of small grain decreases with the increase of sintering time.
Polarization of grain boundary may be little.
Space charges in grain boundary exclude polarization charge on grain surface, and depletion layer on grain surface can be formed [14].
The remnant polarization of the sample with large grain size is more than that of the sample with small grain size.
So reversal polarization process of a ferroelectric domain is more easy inside a large grain than in a small grain [15].