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The prior austenite grains of DQ steel remains as deformed and elongated along the rolling direction, whereas the RQ steel reveals equiaxed grain morphology due to the complete recrystallization during reheating process at 900˚C.
The effective austenite grain size of DQ-T steel is found to be slightly finer compare to RQ steel.
The prior austenite grains of DQ steel are elongated in parallel to the rolling direction, within which a large amount of deformation is present, whereas equiaxed grains morphology is observed in RQ steel.
In RQ steel, a prior austenite grain has been divided into several martensite packets, which had separated by high-angle grain boundaries (Fig. 2(b)).
For two steels after tempering, there are a large number of precipitation in the prior austenite grain boundaries and martensite lath boundaries (Fig. 2(c), (d)).

There are number of twins found in 870-Q Fig. 8-(c).
Grains annex and grow up.
Grain boundaries get thin and straight.
The TEM results show there are a great number of needle-like twins.
Temper at this moment, the ductility and corrosion resistance of alloy increase due to β-Zr which precipitates along the grain boundaries. 7 Quench at a higher temperature above Tcq, the microstructure gets fine and a large number of twins form.

Morphologies are fragmented and a large number of clusters of globular cells or dendrites are distributed in a cross section.
Indeed, the solute layer developing around the grains is of the order of the spacing between the grains.
The same methodology was used for modelling the columnar grains and the equiaxed grains.
The output of the CA model is the grain structure.
It should also be said that the grain structure model only considers the formation of equiaxed dendritic grains: no globulitic grain with a high inner volume fraction of solid is taken into account.

More recently, the deliberate establishment of a bimodal grain size distribution in these materials (combination of nano- and micron-grained structures) was reported to result in high tensile strength together with reasonable tensile ductility [2,3,4].
Attempts were also made to improve the ductility of the nano-crystallite materials by bimodal grain size distribution [with a controlled fraction of nano and micron grains] in a precipitation hardening 2219 Al alloy.
As expected, the crystallite size decreases and lattice strain increases with milling time reaching about 40nm and 0.3%, respectively, after 30h of milling, which is due to the large number of defects introduced due to severe plastic deformation during milling.
The alloy containing 0% CG (i.e. fully nanostructured) powder exhibited uniform nanocrystalline grains with a few percent of residual coarser grains in contrast.
It can be seen in Table 1 and Fig. 5 that (compressive) ductility increases with increasing coarse grain content where as YS and US decreases with increasing coarse grain content.

The electronic charges in grain boundaries and grains are compared with each other.
It is well known that ceramic materials are comprised of grains, pores and grain boundaries.
When the grain size remains the same, the creep resistance is determined by grain boundary sliding which is controlled by grain boundary characteristics [6, 7].
Where, the optimization convergence standard is Fine, the energy deviation is 10-5eV/atom, the kinetic energy cutoff value is 340eV, the precision of self-consistent field is 10-6eV/atom, the number of empty bands is 20 and the k-point count in reciprocal space is 6×4×1.
Si-O at grain boundary and Al-O in grain is the weakest.

With cooling rate decreasing, grain size in normalizing samples increases gradually, and the strength decreases.
With the holding time extending, grain growth is not obvious, and the strength decreases.
During rolling process, original austenite grain is crushed, and during normalizing process, the pearlite grains extends along the grain boundaries and are still strip-liked distribution in the crushed grains.
The reason may be that the carbides, nitrides and carbonitrides pin in sub-grain and grain boundary, which inhibits the grain growth.
According to the homogeneous nucleation theory, smaller grain size is obtained by increasing cooling rate.

In the given paper results of X-ray study as applied to a number of cladding tubes from Zr-based alloys, worked for several years in reactor, are presented and inhomogeneity of neutron irradiation influence on material of the tube depending on the position of considered fragment relative to lower part of tube is demonstrated.
Reasons of such inhomogeneity consist in different passing of deformation processes in α-Zr grains depending on their initial orientation, controlling operating mechanisms of grain plastic deformation, the attained degree of strain hardening and the final position of grain relative to maxima and minima in the deformation texture of tube material.
Fig. 5 shows, how parameters of X-ray reflection (0002) change for a number of α-Zr grains, responding to sections R–L and R–T in PF(0001) for samples from 2 cladding tubes.
And, when β/β0≈1, the substructure condition of grain under neutron irradiation practically does not change.
Thus, under influence of neutron irradiation initially more distorted grains, located in texture minima, become more perfect, while grains, initially less distorted, localized in texture maxima, acquire additional distortions.

A correlation was established between the concentrations of phosphorous and sulphur elements at grain boundaries and the presence of both creep and brittle fracture induced grain boundary facets.
Table 1 shows individual grain boundary compositions.
In total, eight measurements were carried out (illustrated by the letter A followed by a sequential number in the Table 1).
This number was a compromise between good statistics and oxidation accumulation, as stated in elsewhere [1].
For the ST+PS pre-treated specimen, a large number of inter-granular facets were observed in the high temperature failed notch and low temperature fractured unfailed notch.

Introduction The strength of traditional HSLA steels is contributed by a number of strengthening mechanisms, such as, solid solution strengthening, precipitation strengthening, grain size strengthening, dislocation strengthening and texture strengthening.
The distribution of high angle grain boundary is analyzed by using Photoshop and the result is shown in Fig. 8.
In the initial stage, the high angle grain boundary in bainite lath increases and a small amount of ferrite appears, making the high angle grain boundary between bainite and ferrite increase, the two factors play a leading role, the high angle grain boundary showed an increasing trend in totality.
Considering the above factors, the overall number of high angle grain boundary appears increasing after the first.
Fig. 8 Statistical result of high angle grain boundary Rolling of Steel Rolling Procedure.

Grains have been defined as regions surrounded by 5º misorientation boundaries with a minimum grain size of 2.5 mm.
· Grain Orientation Spread (GOS): This parameter is the average deviation between the orientation of each point in the grain and the average orientation of the grain
As holding time increases, the distributions become narrower, with a significant increase in the number of grains with low GOS values (<2.5º), which can be associated with recrystallized grains.
In all cases a high number of grains with GAM values lower than 0.5º is observed.
The number and size of recrystallized grains increases with holding time (t = 100 and 3000 s).