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If the grain boundary bonding force is strong, transgranular fracture is likely to occur, otherwise intercrystalline fracture is likely to occur.
When subjected to elevated temperature, grain boundary bonding force is decreased by the elevated temperature, thus inclined to exhibit grain boundary bonding force as shown in Fig.2(a), while subjected low temperature, transgranular fracture is often observed, which is shown in Fig.2(b).
(a) Intercrystalline fracture(400˚C，250MPa) (b) transgranular fracture（100˚C，250MPa） Fig.2 SEM images of fatigue crack propagation subjected to elevated temperature Crack tip Crack tip Grain Grain 3.2 Evaluation of small fatigue growth rate subjected to elevated temperature The effective main crack can be easily decided based on SEM in-situ observation.
The relationship between crack length and cycling number in semi logy coordinates is shown in Fig. 3.
Cyclic stress-strain response and low-cycle fatigue damage in ultrafine grained copper.

The actual austenite grain size tests were carried out by oxidation method [12], and the actual austenite grain appearance is shown in Figure.2.
Using the comparative method [12], the average actual austenite grain-size number of original state was evaluated for 8.5.
Original austenite grain appearance The mechanical properties tests [13-15] were carried out for steel plate 12MnNiVR in supplier states (thickness 21mm), and some of experiment data are shown in Table 2.
Due to second phase of granular dispersed particles, which is formed by micro-alloying elements V,Cr,Mo,Ti, etc, can effectively prevent the grain and microstructure growth and coarsening, therefore, the influences of heat preservation time on hardness of steel are small.
Metal-methods for estimating the average grain size, 2002(National Standard, In Chinese)

The number and size of droplets increased with increasing of Nb addition.
The average grain size of (Ti0.5Al0.5)N, (Ti0.475Al0.475Nb0.05)N and (Ti0.45Al0.45Nb0.1)N was respectively 14.8nm, 14.3nm and 13.4nm.
The Nb addition slightly led to effect of grain refinement.
The proper degree of application of negative bias reslutes in dense structure, fine grain and suitable compressive stress.
For (Ti0.5Al0.5)N after 10h oxidation, the crystalline grains of oxide were coarse and rough.

Diffraction patterns of two samples are corresponding to typical ZnO (002), (100) and (101) planes, indicating six wurtzite structure and good crystallization, basically the same diffraction peak shape, but its width decreased with the increasing heat treatment temperature , strength slightly increased, which showed that with the increase of heat treatment temperature, grain growth [3].
The average grain size of films was calculated by Scherrer equation, the grain size of the films was 13 nm (400oC) and 19 nm（500oC）.
We could see from the AFM, the grains in ZnO thin films were spherical, the size was uniform.
At the same time, the small grain size of ZnO films, the absorption edge shows blue shift, to the near UV (365nm belongs to the near ultraviolet) response range narrowed, per unit time photon absorption quantity reduced, so that the number of photo induced electron hole pairs decrease, affects the photocatalytic efficiency [4].
The grain size  was small, the surface was uneven, the specific surface area increased, increased the film surface adsorption , also made the film absorption been improved greatly, so it showed better photocatalytic performance [5].

There are two important features on microstructure of shale.Firstly, Shale rocks are composed of rather fine grained particles, and their pores are very small, at the scale of nanometers.Gas slippage is complicate because its pore diameter is typically less than 10 nm.
Introduction Shale rocks are composed of rather fine grained particles, and their pores are very small, at the scale of nanometers.
Hence, we assume is the ratio of number of molecules which gas mean free path is lager than pore size to total number of molecules.
According to Kinetic theory, mean Free path describes the passing away of a gas molecules before collide with other molecules.where mean free path is defined as: (6) If we assume that the distribution coefficient represents the ratio of number of gas molecules which mean free path lager than pore diameter to total gas molecules.we get: (7) Adsorbed gas desorption effect According to statistics by Curtis in Barnett and Antrim shale, there are about 20 present to 85 present gas in absorption[5].
Gas diffusion becomes more important making permeability decrease when pressure draw remain finally.There is a permeability inflection point.The number of pressure inflection point decline from 9 MPa to 3 MPa while the diameter of pore increases from 3 nm to 10nm, which is the main part of pore diameter.Permeability inflection point appears later and decline faster after the point for lager pore diameter.

This number corresponds to the ratio of the thermal transport by convection and conduction.
Figure 4 illustrates the influence of the Peclet number on the process efficiency.
For a Peclet number less than 1, the FZ area are smaller compared to HAZ area, on the contrary, FZ area are greater than HAZ for a Peclet number greater than 1.
Figure 4: Relationship between thermal efficiency and Peclet number (Pe), (a) Pe=0.86, (b)Pe=3.52.
In the HAZ region adjacent to the FZ, the microstructure consists on coarse a grains for CP Ti, and a mixture of a’, primary a and b phases for Ti-6Al-4V.

The interaction between the abrasive grains and the workpiece was approximately regarded as ideal small-scale indentation phenomenon, it was used to evaluate the surface quality in ceramic machined processing that formation of grinding crack and its propagation process, the material removed process and the surface defects of the ceramic grinding, the cutting model proved that although the removed material is usually brittle removal, most of the grinding energy consumption was related with plastic deformation.
A large number of studies showed that there are a variety of wear mechanism existing, generally, believed that the wear resistance of ceramic materials are related to their hardness, toughness, microstructure, defect type and material hardness and abrasive hardness.
The removal of material , on the one hand is due to the front material of the abrasive particles cutting edge is squeezed while the abrasive particles cutting into the workpiece, when the compressive stress exceeds the limit stress of the ceramic material, it is crushed to form a large amount of debris, on the other hand, due to the pressure stress and friction heat, materials below abrasive grains produce local plastic flow and to form deformation layer, after the abrasive grains across, the stress disappears, which causes the deformable layer is detached from the workpiece and form chips, deformation behavior and crack system of ceramic material under abrasive effection can be illustrated in Figure 1 When the material is precision grinding.
When the cutting depth of the abrasive grains further increase the material of non-elastic deformation region under load will increase the lateral flow, non-elastic region is further expanded. the material of the elastic region will be generate friction stress in the non-elastic region / elastic zone boundary due to the friction effect, friction stress makes the elastic zone boundary materials produce tensile stress, when the tensile stress exceeds the ultimate stress of the material (tensile strength), median / radial cracks will form. it is in the place of the maximum tensile stress or in non-elastic / elastic boundary existing one or a plurality of micro-cracks that produc new microscopic cracks.

Pooling layer simplifies the output by performing nonlinear sampling to reduce the number of parameters need to learn.
Classification layers is a fully connected layer (FC) that outputs are the number of classes that network will be able to predict.
One of the recent studies classify 8 different microstructure types of steel (bainite with carbide, granular bainite, columnar bainite, carbide free bainite, ferrite with grain boundaries, ferrite with grain boundaries and small island of pearlite, martensite, pearlite) result from variation in material grade and heat treatment condition by using CNN based microstructural image from light optical microscopy. 1,000 images are selected for training network and the remaining 20,283 images are used for testing.
Results and Discussion The classification accuracy in this study calculated by fraction of number of correct predictions and total number of predictions.
Confusion matrix of the best approach, DenseNet201 with data augmentation, shows the number of samples for each class predicted by system.

We quoted a number of references demonstrating an early-stage difference as exemplified in Fig. 1, and we showed that the erroneous statements about the 50% reduction were largely based on the use of insensitive texture indicators and/or insufficient accuracy in the reading of the indicators.
Furthermore, the intermediate development of the {111} texture is heavily affected by grain size: the {111} texture is very strong in brass withy very coarse grains, and it is absent in brass with very fine grains.
The heavily twinned grains, the grains with bundles, deform by slip on one single slip plane, i.e. a non-Taylor slip pattern.
This obviously requires that the individual grains “remember” their identity as one original grain rather than loosing it by disintegrating into differently deforming local zones.
The general observation on the twinned grains during the development of the brass-type texture is that there is one twin system in one original grain, i.e. that the individual grains do remember their identity.

Machining cracks sometimes have been difficult or impossible to find especially in toughened ceramics with interlocking grain microstructures that create rough fracture surfaces.
Machining cracks are relatively easy to detect in homogeneous materials such as glasses, single crystals, very fine-grained fully-dense, or very coarse-grained materials (wherein the machining crack may be entirely within one grain).
Fig. 3 shows that this SRBSN has needle-like beta silicon nitride grains, 0.5 µm to 3 µm wide by up to 10 µm long , that are bonded by a second phase.
It did have much more grain pull out, fracture, and fragmentation.
Evidently the benefits of the enhanced fracture toughness due to the interlocking grain microstructure occur during crack initiation or pop in.