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Quantitative prediction of transformation textures in steel becomes possible if a variant selection rule is taken into account, in which ferrite nucleating on austenite grain boundaries prefers to have orientation relationship with two neighboring austenite grains at the same time.
These textures should be fairly precisely reproduced from the textures of γ, since the transformation from γ to α can be regarded as simple rotation of cubic crystals with a certain number of variants (24 for the KS relation).
It is perhaps because the precise double KS relation can occur only for special γ grain boundaries.
The α particle nucleates on a grain boundary and grows into γ1 as the i-th KS variant.
Conclusions Assuming the double KS relation, in which the majority of α nucleating on γ grain boundaries holds KS or near-KS relation to γ on both sides of the grain boundary, enables us to quantitatively simulate the texture transformation from γ to α.

The number of elements used was about 6000 with the minimum element size set to be 0.02 mm.
The calculation of grain size may be performed with all constitutive models.
Fig.3 Distribution of grain size and temperature in ASBs (a) grain size (b) temperature Fig.4 Grain size and temperature versus arc length along the path from node A to node B Fig. 4 shows the model prediction of the grain size and temperature along the path from node A to node B.
When the temperature of the material exceeds 500°C, the grain size begins to decrease.
Fig.6 The evolution of the grain size in ASBs Fig.6 shows the evolution of the grain size in ASBs during the formation of the first serrated chip.

In general, single nano-sized grain (40-80 nm in diameter) with moderate roundness and sphericity could aggregate into the compound grain, and thickness of the nanocoating (thin shell, film) might reach from μm to cm scale in different rocky materials.
Nano-sized grains with better roundness and sphericity were sparse and the number of the compound grain was smaller (Fig.3c).
Some of them can be called ideal equivalent grain [8] with homogeneous grains (∅ 75-85nm), and nano-lines parallel to shearing direction (Fig.3d), Note that the thickness of the nanocoating of the shear slip surface is about 1-2μm. 4.
(c) Sparse nano-sized grains and part drawing elongated form (arrow) (from Fig.2b).
(ii)Strain softening, which expresses a shear slip weakening, a static annealed cooling or a thermal decomposition[19], could produce the nano-sized grain rheology and aggregating actions from single to compound grains (Fig.1c,f, Fig.3b,c).

It is well known that the strengthening effects of low carbon steel come from solid solution, grain refinement, precipitation and dislocation, while grain refinement is the only mechanism that simultaneously improves the strength and toughness.
So grain refinement is the major strengthening mechanism in experimental steel.
Lath width of acicular ferrite is about 1μm, which is treated as valid grain size.
Grain refinement hardening effect can be described by well known Hall-Petch equation Although quasi-polygonal ferrite existed in experimental steel, grain refinement hardening effect caused by acicular ferrite is important.
So the crack propagation becomes difficult due to the presence of a great number of obstructions per unit length.

In addition, some scholars and organizations made large number of theoretical studies and experiments in improving the performance of plate research aspects[1~3].
It must be ensured the cumulative reduction rate of 45%, because rolling reduction in the first few passes before finishing rolling is too small to easily lead to coarse grains, it is unfavorable to the promote refinement Austenite grain and improve the strength and toughness of steel.
After the phase transition it brings refined ferrite grain.
Determine blank size is 220 × 1600 × 1630 (mm) based on design principles of blank, the number of times is one.
Table1 Calculated and measurement value of microstructure percent of 16MnR plate F（%） P（%） B（%） Calculated value 76.28 21.03 2.65 Measurement value 76.04 23.96 ------ Table2 Calculated and measurement value of properties of 16MnR plate Austenite grain size（μm） Austenite grain size Ferrite grain size (μm) Ferrite grain size Yield strength （MPa） Tensile strength （MPa） elongation （%） Calculated value 28.62 7.24 13.93 9.31 376.7 539.5 26.16 Measurement value ------- ------ 11.11~14.78 9 355.0 520.0 30.00 Application of preset roll gap.

The results shows that the metallographic structure of the flange matrix on both sides of the hydraulic valve is tempered martensite and ferrite, and a large number of corrosion-resistant phases are distributed on the grain boundary, as shown in Figure 2, and the matrix structure of bonnet is tempered martensite, as shown in Figure 3.
The results show that the Cr content of the corrosion-resistant phase at the grain boundary in the flange structure is 2% - 3% higher than that in the grain interior, that is, the flange grain boundary is a high Cr region and the Grain interior is a low Cr region, as shown in Fig. 6.
Under the microscopic view, it is difficult to corrode the grain boundary and easy to corrode in the grain interior.
Improper heat treatment process will lead to a large number of Cr rich corrosion-resistant phases ((CrFe) 23C6) on the grain boundary of the material, which will lead to Cr poor regions in the grain boundary of the material [14-17].
The results of comparative analysis of grain boundary and grain internal composition in the scanning electron microscope analysis of the above metallographic samples can be confirmed.

Crosssection analysis revealed a continuous layer of chromia had formed beneath the outer alumina scale, together with a large number of voids (Fig. 1).
The number of voids appeared to differ slightly from one side of the sample to the other.
The boundaries between grains are dominated by high angle grain boundaries and the grains contain very little lattice distortion and few sub-grain structures.
FeCrAl foil samples oxidised for 600 hours presented a large number of voids that are filled or partially filled with chromia.
Since only a limited number of samples have been studied to date, specific examples of cracked alumina scale, associated with each partially filled void not always been observed.

A regression model was proposed by Burgess (1978), which was based on mineralogical composition, grain size, hardness and abrasive resistance [1].
The numbers 2, 4, 6 and 8 are for compromise between the above values.
Let us assume ‘A’ number of attributes.
If number of alternatives is K and there are L attributes, then there will be L number of K×K matrices of judgement
Any number of alternatives can be taken with their respective number of attributes.

Standard metallographic sample preparation techniques were applied and an etchant based on picric acid was used to reveal grains and grain boundaries [9].
The cast billet displays coarse dendritic grains and a relatively homogeneous grain size distribution.
The heat treatment of 16 h at 450 °C decreases the number of precipitates at the grain boundaries.
The dendritic microstructure disappears also in the grains.
The material shows a typical microstructure of a twin roll cast strip, with some elongated, columnar grains in the top and bottom area and equiaxed grains in the center.

The area of structure formed out of a single nucleus is called primary grain.
Amount and size of grains depends on number of crystallization nuclei.
If during the solidification only a small number of nuclei is activated, the result is a coarse-grained structure and vice versa.
At higher speed of nuclei nucleation and at lower speed of crystal growth smaller grains are formed.
Dependence of amount of grains on crystallization parameters is determined by the relation as follows: [2, 3] (1) with: N - amount of grains [-], a - diffusional coefficient of proportionality [m2.s-1 ], n - number of nuclei [-], vk - linear speed of crystal growth [m.s-1], V0 - primary volume of liquid phase [m3].