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On the other hand, the abrasive grains of WA are often used in steel materials, and WA grinding wheels are known to be particularly excellent in terms of sharpness among common abrasive grains [6].
As the abrasive grain of the GC wheel dropped off to a lesser extent, there were many remaining protruding abrasive grains.
The hardness of the GC abrasive grains is about twice that of the WA abrasive grains.
The amount of protrusion of the GC abrasive grains is large.
In addition, the number of abrasive grains colliding with the surface increases due to the self-dressing effect of the grinding wheel as the grinding distance increases in the case of a GC vitrified bonded grinding wheel.

On the one hand, effective grinding size of single particle is only 1/3 of the abrasive grain size.
As shown in figure 5, the defects are the main factors of SiCp/Al composites processing and surface quality, so the SiC particle removal way plays a decisive role in the formation of machining surface[5]. 4.2 Removal mechanism of SiCp/Al composites For a single abrasive grain, while abrasive grains of wheel grinding into and grinding out test pieces, the following situations will appear: When abrasive machining process of specimen is on the Al substrate, then the actual occurrence of a metal material that is removed, occurring rubbing, ploughing, forming debris; When abrasive grains grinding into the Al matrix and grinding out SiC particles, the grinding force generated by movement of abrasive grains in the Al matrix is small, processing to two-phase junction and coming into contact with SiC particles, the grinding force increases rapidly, under the impact of abrasive grains and shear forces, SiC abrasive particles produce small cracks.
With the further movement of the abrasive grains, these cracks will extend to the internal of SiC particles, making SiC particles crack; When abrasive grains grinding into SiC particles and grinding out SiC particles, under the effect of grinding force and vibration of machine tools, SiC particles surface occur micro-cracks, SiC particles are removed in the form of tiny fracture.
As processing continues, the abrasive particles deep into the specimen, cracks are more dense, plastic deformation is more obvious, gradually forming the plastic stress below abrasive grain field, so that SiC particles occur plastic deformation, removed in the form of fracture.
Thereafter, abrasive grains grinding out the SiC particles, leaving a large number of cracks on its surface and the residual stress remaining in the grinding area; When abrasive grains grinding into SiC particles and grinding out the Al matrix, when encountering the Al matrix in the two phase junction, grinding force decreases, the form of SiC particle removal is consistent with the form of its internal surface removal[6].

A number of recommendations are given for the effective use of gangue and fly ash in high performance concrete.
However, a combination of gangue 15%, fly ash 10%, slag 10%, 10% silica fume, and 55% cement, number 5, produced a reduction in strength of about 8.74%.
On the average, mixes number 2, 6,10,15,17 performed better than most mixes containing a single admixture.
From the photos, the sample of the concrete 28d benchmark concrete during hydrating, the spherical fly ash grain and hydras have clear cracks on the surface of the fracture there a great deal of bare smooth fly ash balls and fly ash grains that can leave half-globe pits after they are set aside.
The hydras form the strong whole body with not hydrated grain gels.

The ingots were forged into thick plates, from which specimens with a dimension of 6mm in diameter and 80mm in length were machined.The specimens code number from CCT-1 to CCT-36.
The value beside the curve are percentage of the phase and the number under the curve is the hardness of the sample under the cooling rate where the load is 5kg to the diamond indenter.
In addition, the base metal have very fine grain from the Fig1.
Reference [1] A.Jocot and M.Rappaz, A two-dimensional diffusion model for the prediction of phase transformations: application to austenitization and homogenization of hypo-eutectoid Fe-C steels Acta.Mater, 1997, 45(2) p75 [2] Ming-Chun Zhao,Ke Yang,Fu-Ren Xiao,Yi-Yin Shan, Continuous cooling transformation of undeformed and deformed low carbon pipeline steels,Materials Science and Engineering, 2003 A355,p126-136 [3] P.J.Alberry,B.Chaw,W.K.C.Jones, Prior austenite grain growth in heat_affected-zone of a 0.5Cr-Mo-V steel, Metals Technology, 1977, p.317-325 [4] S.lechuk,M.Militzerand E.B.Hawbolt.
Modeling austenite grain growth kinetics in a Ti-Nb HSLA steel, Int.HSLA Steel’ 2000, Beijing, p181-186.

According to the coincidence lattice model of large-angle grain boundary used commonly in modern times, the corresponding structural condition is analyzed, i.e., the crystal structure of graphite should have the better lattice contract ratio with the crystal structure of its annexed heterogeneous particles.
There are 7 kinds of covalent bonds which can not be neglected in the structure unit of graphite, their bond names, experiment bond lengths Dna and the numbers of equivalent bond Ia are shown in Table 1.
There are 4 kinds of covalent bonds on the crystal plane (0001), they are ,,and and corresponding to,,and of the phase space separately, their numbers of the equivalent bond on crystal plane (0001) are I1=6, I2=6, I3=6 and ID=6 separately.
There is only one kind of covalent bond on its crystal plane (111), and it is corresponding to of the phase space, its equivalent bond number on crystal plane (111) is I1=12.
There is only one kind of covalent bond on its crystal plane (111), it is corresponding to of the phase space, and its equivalent bond number on crystal plane (111) is I1=12.

The roles of ECAP parameters (die-channel angle, the number of pressing passes, billet rotation between passes and relief angles in the die) in grain refinement have been of primary interest.
Prior to ECAP, these materials were given annealing treatments resulting in initial recrystallized grain sizes of ~1 mm.
Fig. 4 shows typical TEM micrographs; these images reveal microstructures having comparable (sub)grain sizes (~1.2 µm) and morphologies in these two samples.
Lowe (eds.).Ultrafine Grained Materials III (TMS, Warrendale, PA 2004) [2] N.A.
Swisher, in Ultrafine Grained Materials III, edited by Y.T.

Grain size is relatively small, the average grain size is 4.0~5.0 μ m.
Coarse grain zone( Figure2b shown) consists mainly of granular bainite, a larger size of M-A island, and apparent size larger than 100 μm austenitic grain; coarse-grained zones(Figure2c shown) are further away from weld of austenitic grain size and significantly reduce the dimensions of M-A island.
Figure 2d with polygonal ferrite in an organization, there are also small amounts of pearlite and cementite, are fine grained zone.
Test results are shown in table 7, whether the parent material, weld or coarse grain HAZ area with good CTOD values, features far exceed the BS 7448 and CTOD values in DNV OS-F101 standard provided greater than 0.2mm.
(2) deep-sea pipeline steel , the microstructure of base metal is acicular ferrite-dominated, and a small amount of granular bainite, weld HAZ of coarse grain area is composed of granular bainite, a larger size of M-A island, fine grained zone polygonal ferrite-dominated, there are also small amounts of pearlite and cementite

The grain length in rolling direction is about twice the size of the grain height due to the cold rolling.
retained ferrite 20 µm 50 µm 100 µm former austenite grain former austenite grain Fig. 4.
An acicular structure can be seen, in which some of the previous austenite grains are still visible.
Due to a small sample number of three, the error bars do not show the standard deviation but the maxima and minima of the detected curves.
A longer period causes grain growth leading to a lower resultant hardness.

Results and discussions Fig1(a) exhibits the morphology of Ni-Cu nanopowders, which are mostly spherical and mean grain size of around 55nm.
Fig.3(b2) shows the transcrystalline fracture manner and the grain are all around the diameter of 100-200nm judged by the size of dimples.
According to the above experiments, the higher the sintered temperature is, the larger the grain size becomes, and the weaker the strength is.
So the intrinsic reason for the enhancement in the strength of the samples sintered by SPS is the existence of high-energy grain boundaries.
The high strength of the sintered specimens can mainly attributes to the existence of a large number of grain boundaries.

When the current density is small, with the smaller and uniform particle size of surface, the large nucleation rate of the unit time per unit volume, the more number of nuclei per unit volume and the smaller each grain growth leeway, the crystal grains will grow finer.
Simultaneously, the smaller of speed of grew up, the more nuclei will be formed and the more tiny crystal grain will be in the growth process.
Conversely, the smaller the nucleation rate and the greater the growth rate, the more coarse grains will be taken shape.
As the current density increased, the nucleation rate decreases, the grain growth rate to accelerate, get more coarse grain.
Due to the large current density, the unevenness of the nucleation is prominent, causing the uneven grain of the surface of the grain size distribution and partly grow rapidly, so that the particle size is unequal.