Search results

This resulted in an equiaxed grain size of 68 ± 4 µm.
As annealing proceeds the recrystallising grains grow into the non-banded grains.
Discussion From Fig. 2 it appears that nucleation of recrystallisation takes place preferentially at grain boundaries and inside grains with well developed microband structures.
The number of subgrains per unit volume α (δ) -3, and, assuming that the shapes of recrystallised grains and subgrains are the same, means that, from equation (5), the probability of a subgrain forming a nucleus increases somewhat with decreasing subgrain size.
If these were the only sites, one should consider only the number of subgrains impinging on boundaries.

Besides focusing on the number of applied dimensions, a novel approach was introduced by Y.Wang et al. [5], who regarded the wheel surface to be consisting out two characteristic wavelengths.
As a result, the number and configuration of the abrasive tool points in the grinding wheel surface have been derived.
The dimension of grains are not a constant number, instead they comply with a normal distribution.
In the model the Monte-Carlo principle is applied to generate the grain diameter number which complies with the normal distribution N(Dnorminal, σ).
The static grain count is defined as the number of abrasive grains per square millimetre on the wheel surface.

The orientation numbers between 1 and Q are randomly assigned to each lattice site of the microstructure.
Si denotes one of the Q possible grain orientations number at site i.
Sj represents the orientation number of site j which is the neighbor of site i.
The above steps are repeated until the desired evolution step number is reached.
The orientation number Q of lattice sites for matrix phase ranges from 1 to 200.

The simulation results showed that the greater the restored energy, the greater the number of the recrystallized grains.
In order to simulate grain growth in a single-phase system, only the free energy density function f0 is required to provide a certain excess free energy at the grain boundary.
The parameters of the gradient term K2 and the coupling term K1 have been determined by the grain boundary energy and the grain boundary range.
The smaller grains shrink until they are absorbed by the surrounding grains, and the grain morphology remains relatively stable during the growth process, which is consistent with the main characteristics of grain growth.
On the other hand, the greater the restored energy, the greater the number of the recrystallized grain.

(a) (b) Fig.3 Orientation dependence of active slip systems, (a) number of active slip systems as a function of orientation at 0.003 tensile strain, (b) active slip systems predicted by Schmid law Fig.5 Average number of active slip systems vs. tensile strain Fig.4 Evolution of number of active slip systems with tensile strain 3.3 Slip system activity.
In this study, the number of active slip systems in a grain is determined to be the smallest number of the slip systems necessary to account for 90% of the total absolute accumulated shear of the 12 slip systems [10].
Fig. 3(a) shows the orientation dependence of the number of active slip systems at the early stage of deformation (0.003 tensile strain), from which it can be found that the (100), (111) and (110) oriented grains have respectively eight, six and four active slip systems.
The evolution of the number of active slip systems with tensile strain is given in Fig.4.
The simulation results show that: (i) there are few grains having one, five and seven active slip systems throughout the deformation, and all the grains activate more than one slip system after a very small strain; (ii) the number of grains with four, six and eight active slip systems increase as the tensile deformation going on, but at relatively large strain, the grains with four slip systems decrease, these behaviors are obviously related to the rotations of grains to the directions of (111), (100), and the (100)-(111) line; and (iii) grains with two and three active systems decrease with tension because more slip systems are needed to accommodate large deformations.

Grain refinement at the central zone is faster due to the strain inhomogeneity.
But the peripheral zone is also refined with the number of CCDC.
The number of initial tetrahedral elements was 30000.
Moreover, the strain gradient increases with the number of CCDC.
While at the peripheral zone, original grain boundaries still can be seen though there are lots of deformation bands in some grains (Fig. 5(b)).

The as-extruded alloy bars retain equiaxed grains with a large number of precipitated phases, β-Al12Mg17 and AlMg2Zn.
The grain size is about 2 mm.
Many small precipitates distribute on the grain boundaries and inner grains.
There exists a large number of dimples, some cleavage steps and small tearing cracks on the fracture surface, which suggests toughness fracture feature.
A large number of precipitates (β-Al12Mg17 and AlMg2Zn) with a particle size of about 200nm occurred during hot extrusion, which distribute along the grain boundaries and throughout the interior of the grains

RE content affects grain size by influencing number and size of fine inclusions in the finished steel sheets.
It can be understood the number density descreases.
AlN and MnS which size is smaller than 1μm can be inhabitors to prevent from grain growth.
RE addition in the steel can refine grains.
The number density of fine inclusions with size less than 1μm in the samples decreases, and the grain of the finished steel grows up homogeneously which is benefit for its magnetic properties.

Ultrafine-grained (UFG) and nanostructured metals have a notable increase in strength compared to conventional coarse grained metals due to the grain boundary strengthening effect.
A arge number of SPD methods have been proposed in order to obtain UFG materials during the last three decades.
The processing method has a major impact not only on grain refinement level but also on many other characteristic microstructural features, such as grain shape, the direction of grain elongation, grain size distribution and density of dislocations.
There is a clear dependence between grain size and applied strain – the higher strain, the smaller the grain size.
It has been proved that the processing route has the major impact on the average grain size, grain size distribution, grain shape and the distribution of grain boundary misorientation angles.

So this high load level of microscopic compressive stresses of the (11-20) oriented grains and the increase in these microstresses with increasing number of cycles supports the increasing twinning of this grain fraction.
Due to the larger grain sizes present in series A, the increase in defect density with increasing number of cyclesis not sufficient to reduce the twinning / detwinning activity. 4.
The increasing defect density hinders the detwinning so that the fraction of stable daughter grains increases with the number of cycles.
However, under compression the fraction of twinned grains increases with the number of cycles due to the high microstresses of the (11-20) oriented grains.
Due to the larger grain sizes in the microstructure of series A, the increase in defect density with increasing number of cycles is not sufficient to provide an increase in hardening in the compression regime.