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Compared to the grains with bigger size, the small ones have smaller bonding strength by the cured resin, it is easier for such grains to get apart from the bonding material.
As been discussed, only the grains with bigger size are embedded on the surface of grinding wheel, number of abrasive grains which are actively grind the work piece surface decreases, which leads to the load per grain increases and hence the average surface roughness gained becomes greater.
Three reasons for the decrement of MRR include the fracture of grains, load per grain decrease caused by the fracture and blunts of grains.
In the grinding operation, due to the released abrasives being flushed off the wheel, the number of active abrasive grains becomes smaller, or the concentration of abrasives on the wheel surface decreases, therefore, much less material is removed.
However, after that, because some grains get released, the grind/lap wheel becomes more as a lapping plate with smaller size grains free to rotate on its top, meanwhile, grains with bigger size are still embedded in the wheel.

The massive ferrite separate out a small number of tiny carbides.
Fig.c) show that there are also a large number of sub-boundaries in the grain of massive ferrites and some small carbides that are precipitated along the grain boundaries.
The number of granular carbides significantly increases, and the particle size is larger.
A large number of carbides precipitations precipitated in the grain boundary between massive ferrite and bainite phase, which grew up from grain boundary to bainitic grains, and became the larger carbide particles at the junction of three grain boundaries.
The microstructure of 10CrMo910 steel after running 147,000 hours is still a large number of bainite and a small amount of massive ferrite; subgrain boundaries and dislocations significantly are reduced in transgranular of bainite; subgrain boundaries and dislocations almost disappear in transgranular of massive ferritic grain. 2.

Due to the f(amin) represents the number of the boxes of the same maximum height probability (NPmax(e) = Namin(e) ~ e--f(amin)), while f(amax) reflects the number of the minimum one (NPmin(e) = Namax(e) ~ e--f(amax)), the Df describes the ratio of the number of the maximum probability and that of the minimum one: NPmax(e)/NPmin(e) = e -Df.
Experimental results indicate that the number of lowest valleys of all HfO2 films is larger than that of the highest peaks (at e = 1/512, NHmax/ NHmin » 3, 77, 11, 29 for HfO2 grown at RT, 200 oC, 400 oC and 600 oC, respectively).
The grain sizes become larger with the increasing temperature.
As listed in table1, it is important to recognize that d spacing (d-111) decreases with increasing grain size below 7 nm, but becomes larger with grain size of 14.8 nm.
Fig.3 (b) also shows the relationship of Da and the grain size of HfO2 films.

It is also obvious that the number of primary α-Mg in the slurries increased by UV.
Because of ultrasound and cooling impact stemmed from the chilling mold, huge number of nuclei still exist in the remnant liquid.
The decrease of APD and increase of primary α-Mg grains result in fine grain boundaries and second phase in the semisolid Mg alloy.
It can be seen that the bright phase in gravity casting alloy distributes nonuniformly and a number of coarse blocks concentrate at the junctions.
The remnant liquid is divided into huge number of small molten bath by the fine α2-Mg grains, and the growing space for LPSO structure is limited to poky intergranular areas.

Dimensions of packets and blocks could not be determined with high accuracy due to the fact that a limited number of areas could be analyzed by careful orientation analysis [3].
Average size of these grains is ~2mm and, therefore, the 9%Cr steels are ultra-fine grained materials.
No remarkable changes in size and number of these carbides located along block boundaries were found.
This is caused by large Zener drag pressure on these HAGBs due to large number of the M23C6 carbides and Laves phase.
By contrast, minor normal grain growth occurs under creep.

An austenitic grain is considered (see Fig. 1, middle).
Within this grain, several martensitic variants, potentially all 24, may transform.
To homogenize the behaviour of 24 variants towards the response of the grain, the grain is virtually split in several domains.
The number and the volume fraction of these domains, is however, not known beforehand, but is obtained as the outcome of the transformation model on each of the potential variants.
The stress-strain responses of the transforming grain are also compared to the responses of the austenitic grain if no transformation would have occurred.

Quaternion is a number that extends the complex number, and can represent the three-dimensional orientation and rotation.
A quaternion is a number that extends the complex number and expressed as , where and are imaginary units satisfying the following relationships: (2) A quaternion can be considered as a number containing one scalar element and one three-dimensional vector element, so that a quaternion can express a three-dimensional rotation.
The both crystal grains grow isotropically.
When the crystal grains come in contact with each other, the grain boundary is formed due to the misorientation between two grains.
In contrast with the case 1, the grain boundary is not formed when the crystal grains come in contact with each other, and two grains merge into a single grain, because two crystal grains have the identical orientation.

But the impact property obviously decreased with the increase of quenching temperature, that is due to the grain coarsening.
A number of studies about the steel are reported so far.
On the one hand, carbides dissolved and more alloy elements diffused into austenite grains with the quenching heating temperature increased and heating time prolongated, that enhanced the solution strengthening and the grain boundary strength.
On the other hand, the grain and the martensite lath grew up with quenching heating temperature increased and heating time prolongated, that weakened the grain strengthening.
Fig.3 shows the average grain size after quenching at different parameters.

Processing of a large number of novel steel types, such as DP, TRIP, CP and TWIP, and high-strength low-carbon bainitic and martensitic DQ-T steels, have been developed based on physical simulation and modelling studies.
Among stainless steels, guidelines for processing of ultra-fine grained austenitic stainless steels have been created.
For past 15 years, a large number of test programs have been accomplished on a Gleeble 1500 simulator at the University of Oulu to investigate and develop thermomechanical processing of steels.
It was also realized that the Nb alloying tends to increase the ferrite fraction but refines the grain size.
Ultra-fine austenite grain size in reversion annealed 301LN and flow stress curves following different annealing treatments.

Numbers of readings were taken on each sample to obtain reasonable statistics relation to their hardness values.
In this present study, we calculated size of α grain, parameter of non-uniaxiality of α grain, percentages of α grain, number of α grain per unit area etc manually in a metallurgical microscope (ZEISS, AXIO VERT 40 MAT) taking each individual alpha grain into account.
There was similarity in microstructure with respect to number of alpha grains per unit area, percentage of alpha phase, average size of alpha grains, and parameter of non-uniaxiality of alpha grain at the necked portions while being the part was air cooled or water quenched.
At the head portion, difference in microstructure have been observed with respect to number of alpha grains per unit area, parameter of non-uniaxiality of alpha grain while being the part was air cooled or water quenched.
At the necked portions of the specimen, the microstructures were almost similar while being water quenched or air cooled with respect to number of alpha grains per unit area, percentage of alpha phase, average size of alpha grains, parameter of non-uniaxiality of alpha grain and micro Vickers hardness value.