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With the roles of above two interactions, some EBSD characteristics such as the packet size and the number fraction of high angle grain boundaries all have a peak present at 740℃ Introduction HSLA100 steel has been developed widely in recent years owing to an excellent combination of high strength, good toughness and excellent welding performance.
Fig.3f shows the number fraction of HAGBs (≥15°) in the test samples quenched at different temperature in the 2-phase region.
With the quenching temperature increasing, the number fraction of HAGBs increase gradually to peak at 740℃ and then decrease gradually, and finally the fraction of HAGBs fluctuate slightly above 800℃.
With the roles of above two interactions, some EBSD characteristics such as the packet size and the number fraction of high angle grain boundaries all have a peak present at 740℃ (Fig.5).
With the roles of above two interactions, some EBSD characteristics such as the packet size and the number fraction of high angle grain boundaries all have a peak present at 740℃ References [1] E.J.

Ferrite Grain Refinement during Hot Rolling of Seamless Tubes R.
The composition of the steel was 0.2C, 1.44Mn, 0.24Si and 0.12Cr, all numbers in % weight.
The starting grain size for the torsion experiments were certainly higher than 100µm, as there was no pinning effect limiting grain growth during heating.
The grain size of torsion sample quenched at a point simulating withdrawal of the tube from TF shows that the austenite grain size leaving TF is about the same size as for the grain which left CMM.
This in turns determines final ferrite grain sizes bring refinement of these grains by a factor of almost 2, that is, from 20.8 to 12.4µm.

In addition, an inclusion of length scale of grain to simulate the SIMT behavior is very important and the studies which consider the effect of numbers of grains and representative grain morphologies effectively are still developing.
The actual TRIP steel is a polycrystalline material which consist an aggregate of a number of grains and the martensitic content varies from grain to grain.
A set of Voronoi tessellation with the numbers of crystal grains of 6 and 20 is chosen as shown in Fig. 2 (a) and (b).
Here, the total number of variant systems is 24 [14].
Next, Fig. 5 shows the distribution of phase for the case of 20 grains with Pattern 2 in order to investigate the effect of numbers of grain on the SIMT behavior.

A grinding wheel comprises of a large number of grains and their size and distribution are random and therefore it makes the grinding process a very complex machining process to be studied.
However in reality, the single-grain cutting process is not easy to be studied using traditional experimental approaches because the grain is too tiny at micro scale.
Further Niklaus et al.[10] conducted a simulation of single grain cutting using the SPH method to investigate influences of grain geometry, grain orientation and grain placement on cutting forces, burr generation and chip removal rates.
Modeling of Single-grain Cutting In the current study, the single-grain cutting model was idealized as a RHA 4043 workpiece (160 μm in length, 100 μm in width and 40 μm in height) and a single cutting grain as shown in Fig. 1.
Fig. 2 The numerical modeling of the single-grain and the geometry of the grain In the numerical simulation, the grain was moved along the positive direction of the z-axis in a defined moving path depicted in Fig. 3.

The upsetting and extrusion processes are repeated over and over again till the desired number of cycle is reached.
This deformation pattern becomes predominant with increasing number of RUE cycle (Fig.2d-f).
Macrostructure of OFHC Copper subjected to increasing number of RUE cycles.
With increasing the number of RUE cycle, the distribution of these fine grains increases at the expense of coarser grains.
Microstructures at various regions with increasing number of RUE cycles Microstructures shown in Fig.4c-f provide direct evidence to the evolution of new ultrafine grains as per MSB model during RUE.

Therefore, the number of segregating impurities or solutes at the grain boundaries is less than in the case of structure that does not contain subgrains [5,6].
As can be seen, the grain boundary is also enriched in a network of grain boundary precipitates.
This is similar to the grain boundary precipitation of standard 5083AA.
the grain boundaries and hence intergranular corrosion.
Addition of Zn kept precipitation inside the grains, which results in grain boundaries free from precipitate.

Smaller grain sizes lead to stronger material, making the ultrafine-grained (UFG) alloys very promising to achieve record mechanical strengths.
During milling the great number of defects are created and nanoscaled domains are formed leading to an interfacial energy sufficiently high to overcome the positive heat of mixing of immiscible systems [58,59].
In this situation, the final microstructures (the number of precipitates, their density, distribution and volume fraction) are also relatively difficult to control because of the strong interaction between defects and solute atoms.
In UFG materials the proportion of grain boundaries is much larger than in conventional coarse-grained alloys.
The role of grain boundaries.

Introduction The occurrence of variant selection during the transformation of austenite into martensite/bainite in steels and in Fe-Ni alloys has been extensively studied and a number of models, e.g. [1-3], have been proposed to account for this phenomenon.
However, the texture obtained in this way can more precisely be referred to as a "microtexture" and its comparability with the macrotexture will depend on the number of actual grains covered by the scan.
Outlines of prior-austenite grains can be deduced from the orientation differences of one grain with respect to its neighbors.
One such γ grain is illustrated in Fig. 3.
The contour lines link points that represent the same number of orientations per specified volume (0.0207×0.0207×0.0207) of R-F space.

refers to the total density of dislocations in coarse-grains and the nano-grain.
The back stress induced by dislocations accumulation can be simply expressed as (4) whereis number of dislocations that emit from the nano-crack tips.
As illustrated in Fig. 1, we only consider the number of dislocations emitted from the crack tip of NC copper when the angle is 70°.
can be get from (5) where is the maximum number of edge dislocations that can be emitted from the crack tip along one slip plane, it can be get from the Fig. 2.
The strength of the material decreases with increasing the grain size of the coarse grain.

(2) Where:- average grain size,- dynamic recrystallization volume fraction, - dynamic recrystallization grain size ,- initial grain size.
Grid number is 80000; the mould is arranged as a rigid body, the whole grid division number 10000.
Simulation results analysis Analysis of the temporal and spatial evolution of grain.
A large number of deformation occurs in the middle of the process, and most of the region is in the recrystallization temperature range, so a large number of dynamic recrystallization can occur at a high speed.
It can be seen that, time which happens a large number of dynamic recrystallization is at the beginning of the forging process.