Search results

There are a large number of secondary α phase precipitated from the grain boundaries and within grain of β phase undergoing aging treatment.
A large number of equiaxed primary α phase is precipitated at the grain boundaries of the β phase matrix.
The grains have not been refined by subsequent aging process, but the new interface, α/β boundary, has been formed, which introduces a large number of substructures in the micrometer or sub micrometer scale.
On the other hand, the number of grain boundary per unit volume increases by grain refinement.
The grain size of α phase increases with increasing aging temperature, but the number of precipitated phase in unit area decreases with the increase of aging temperature

In the current model, the dynamically recrystallized microstructure will be represented by certain number of representative grain aggregate with different component and different cycle of DRX.
Each grain aggregate has state variables of the component number, dislocation densities, surface boundary area, sum of grain diameter in the grain aggregate, number of grains in the aggregate and volume fraction of grain aggregate.
Where, i represent DRX cycle and j represent component number.
Then, number of nuclei for grain aggregate [j,i] can be defined as follows. . (5) where n, m, Qnucl are constants, f is the volume fraction and Δt is a time increment.
The final tube has an outer diameter of 48.8 mm with thickness of 4mm.The total number of triangular elements used was 4471.

Thus, anisotropic grain interaction occurs.
(5) Note that the ( , , )ijF hklψϕ are not components of a tensor since they relate the lattice strain (a number) to the stress tensor (expressed in the S-system).
For the following discussion such an average of (extreme) grain-interaction models will be called an effective grain-interaction model.
The number of grain-interaction models of extreme types of grain-interaction assumptions is two for bulk materials (Reuss and Voigt).
• For extreme grain morphologies (flat discs and needles), the grain-interaction in the EshelbyKröner model exhibits similarities with the grain interaction in the Vook-Witt and inverse Vook-Witt models, respectively.

Grain Potential Productivity of Cultivated Land in Baoji, Shaanxi Province, China Tuansheng Lia, Haohao Wu,b , Hongzhi Zhaoc College of Earth Science and Resources, Chang’an University, Xi’an, Shaanxi, 710054, China atuanshen@chd.edu.cn, bwhh_xkp@yahoo.cn, c247911938@qq.com, Keywords: grain potential productivity; agricultural land classification; Baoji Division Abstract.
Many scholars have made a large number of researches about the crop photosynthetic potential productivity, photo-temperature potential productivity, climatic potential productivity and land potential productivity from different angles ever since.
In the agricultural land classification, the natural quality index of a classification unit is theoretical standard grain yield got by land conditions of a classification unit revising the photo-temperature (or climatic) potential productivity of the crops, and converted by grain yield ratio coefficient.
Therefore, the utilization quality index of land is a standard grain yield that can be got by increasing investments and use level.
Result analyses The grain potential productivities of cultivated land of Baoji are shown in table 1.

The number of cycles and corresponding fatigue crack length are recorded.Incremental polynomial is used to determinate the crack propagation rate ().
Grain boundaries play an important role in hindering the further propagation of plastic zone.
Fig. 8 Determination of of the critical points (1#) After determining of the critical points, the fatigue crack propagation length in near-threshold zone can be obtained from the corresponding fatigue crack propagation rate and cycle numbers at different test points in the near-threshold zone.
The equivalent diameters of 3~4 prior austenite grains at each critical point are measured, and the average is taken as the corresponding prior austenite grain size .
Relationship between Size of Plastic Zone and Prior Austenite Grain Size 5.1 Size of Plastic Zone at Critical Points.

The total number of grains of 5 grain boundary in whole mapping is 8869 with I AGG grain.
Number of grains included in misorientation calculation seems to be enough to obtain statistics.
Typical and reliable equipment obtaining orientation information is Transmission Electron Microscope(TEM), of which reasonably and practically measurable number of grains is below one hundred.
EBSD mapping and Montage technique used in this study can increase the measurable grain number of statistical data about hundred thousand, which is thousand times larger than TEM.
Large number of captured grain inside AGG grain has high angle boundary of 90°.

With increasing number of ECAP passes and cold rolling reductions, the initial coarse grained structure in the as-received material was transformed gradually into an ultrafine grained microstructure with an average grain size of 0.2~0.3 µm.
For convenience, the tensile specimen is addressed with two letters followed by a number.
The first letter indicates the plane, from which the specimen is cut, and the second indicates the tensile axis, and the number indicates the layers number of the plane, as show in Fig.3.
Microstructure heterogeneity is clearly shown, especially for the case of pass 2, where the distortion of the grains in the microstructure increases with the layer number.
This is confirm in the present investigation by observing the distortion of grains after ECAP.

The effect of grain size on the crack behavior was well explained by the grain size dependence of stress concentration at grain boundaries due to dislocation pile-ups.
And, from the TEM image shown in Fig.1-c), the average grain size is 7μm(circle equivalent grain size).
X-axe shows the rating number of cracking, and Y-axe shows the absorbed energy in compressed to 100mm length.
where σapp: stress in the crystal, σ0: resistance force by the precipitate at the slip in the grain, φ: the stress concentration coefficient at grain boundary.
(2) It is effective to be fine grained for the crack prevention, and it makes the stress concentration reduce at the grain boundary, resulting in prevention of the grain boundary fracture.

Hence, the process consists of a large number of alternating deformations and dwell steps.
In addition, due to the large number of cycles, the modeling results, especially the prediction of grain size, can easily be affected by uncertainties in the input data.
Ring rolling, in contrast, is an incremental forming process in which the ring is progressively shaped in a number of revolutions.
Each point in the ring undergoes a number of deformation cycles with interpass times of variable duration in-between.
During this grains coarsened considerably (cf.

Table 3: Number of grains observed and traces with their inclination relative to RD.
Indeed, a large number of well defined bands are seen inside γ grains.
The Taylor factor does not take into account the number of slip systems which are actually activated to accommodate the local deformation.
If the local misorientation is correlated with the degree of fragmentation (as it seems to be from the EBSD images where crossed slip traces are more numerous in highly misoriented grains), then it should be correlated with the number of slip systems activated in each grain.
The number of bands which can correspond to a <110> pole increases with strain, so does the number of γ grains.