Search results

The main factors in producing of ALFA using the powder metallurgy method are the process of compacting and its large grains.
This is consistent with the analysis of variance; the greatest significant influence is grains size factor, with 74% the percent contribution.
The compressive strength will be increase that is caused by increase of compacting pressure and large grain size.
The main factor which influences compressive strength is the grain size.
The smaller the grain size, the higher compressive strength of ALFA. 3.

The classification of grits can be further specified in terms of the total number of grits per unit area GSTAT or the total number of grits actually engaged in cutting referred to as GDYN or dynamic grits.
If a small sample spacing is employed for measuring the wheel surface then information such as cutting edges and grains will be obtained however, the former can be considered high unstable as the number of cutting edges can quickly change to grain wear or fracturing.
A more stable feature to measure is the number of grains and their overall sharpness.
Selecting the appropriate sample spacing to distinguish the grains from the cutting edges can be achieved using a number of approaches proposed by various authors.
Characterisation Strategy For a grinding wheel to efficiently remove material from a workpiece, a number of criteria need to be met; there should be sufficient grains present, they should be sharp, and ideally should be exposed.

The grain size of longitudinal rolling is close to cross rolling, the grain size is 10µm around, and the grain size of a small number of longitudinal rolling is less than 10μm.
The grain size of mostly of cross rolling is less than 10µm.
We can see fine-grain about 5-6µm and some granular particles dispersed in grains after rolling.
Grain refining.
The recrystallization grain existed as shown in Fig.7 (a) verified its grain refining mechanism during hot rolling.

The texturing development in these superconductors decreases in an efficient way the number of high-angle grain boundaries, increasing the values of critical current densities (Jc).
It can be observed shape and size of grain in the sample.
The objective is to reveal some grains for morphology analysis.
It can be observed shape and size of grain in the sample.
Fig. 4 – Histogram of grain size samples a) Bi0T e b) Bi5T.

These models are based on the results of experimental investigations fulfilled for a number of steels of systematically-varied chemical composition [2,6].
The rate of austenite grain growth (GG) under condition of a grain boundary pinning by undissolved precipitate particles may be expressed as [13]: (1) where is an average grain size (volumetric); is a specific grain boundary (GB) energy; is the grain boundary mobility; is an effective activation energy of the diffusion process controlling grain boundary motion; is a constant (for a given steel) parameter; is a limiting grain size related to Zener’s pressure caused by grain boundary interaction with precipitate particles [13].
Eq. 2 was evaluated by the authors on the basis of the experimental self-diffusion data set obtained by the radioactive isotopes method for a number of austenitic alloys with different compositions [12].
It’s interesting that the proposed model rather precisely captures the process kinetics for a number of steels with substantially different chemical composition in a wide range of temperatures (see Fig. 1a; b; c).
The developed model contains a lower number of fitting parameters than S.F.

It has been shown that the decrease of the gas flow rate favors the increase of the mean grain size of the particles and that the increase of the laser intensity seems to provoke an increase of the mean crystal size and/or crystal number.
The grain sizes are between 15 and 25 nm.
Beyond 0.8 kW/cm2, an increase of the mean grain size is observed.
This increase could come from the increase of nanocrystals size and/or number due to the increase of the flame temperature.
At 1.2 kW/cm2, an increase is observed and interpretated by the increase of the size and/or the number of crystalline domains.

The results show that addition of only 0.20% Zr or 0. 20% Sc to Al-7.2Zn-2.2Mg-1.8Cu alloy can refine grains to a certain degree, and the addition of 0.10% Sc+0.20%Zr leads to stronger grain refinement, the average grain size is only 10-15μm.
When compound adding 0.20%Sc and 0.2%Zr, the average grain size is as fine as 20-45μm，and the grains is replaced coarse dendrites by fine equiaxed grains (Fig. l (d)).
Fig. 1 Optical micrographs of as-cast alloys treated by electro-polishing and anodization (a)Al-Zn-Mg-Cu (b) Al-Zn-Mg-Cu-0.2Zr (c) Al-Zn-Mg-Cu-0.2Sc (d) Al-Zn-Mg-Cu-0.2Zr-0.2Sc Fig. 2 Optical micrographs of as-cast alloys treated by keller's reagent (a) Al-Zn-Mg-Cu-0.2Zr (b) Al-Zn-Mg-Cu-0.2Sc (c) Al-Zn-Mg-Cu-0.2Zr-0.2Sc From Fig. 2, it is evident that the dendritic structure is coarse and a large number of second-phase particles exist within the grains and on the grain boundaries for the alloy with adding 0.2%Zr.
Zr and Sc compound addition in Al-Zn-Mg-Cu alloy could generate strong grain refine effect, fine equiaxed α-Al grain replace thick dendritic crystal. 3.
Grain refinement and superplasticity in 5083 Al[J].

Post-processing the numerical results for a number of grain sub-sets is needed to represent the elastic lattice strains within the material representative volume element (RVE) chosen for the analysis.
Furthermore, once the model has been calibrated, a number of structural realisations can be studied without further experimental input.
TOF patterns contain large numbers of diffraction peaks, each representing the scattering from a group of grains sharing the orientation of a normal to a set of lattice planes.
Post-processing allows average strain values across a number of grains of similar orientation to be obtained.
Agreement is generally good, considering the relatively small number of grains and Gauss points used for the simulation (27000 Gauss points for 600 grains).

Since it’s impractical to obtain the austenite grain size distribution in the beam blank during industrial hot rolling, the calculated rolling loads are compared with the mills loads instead of grain size comparison between the predicted average value and the real ones. 1.
A number of mathematic models [1-3] have been developed in the past few decades.
Results and Discussion Fig.3 describes the temperature distribution in the hot blank after a 30s inter-pass interval, the temperature varies form 1087℃ to 1236℃ in the whole blank.Fig.4 describes the distribution of austenite grain size in a hot blank after a numerical simulation of an 11-pass hot rolling process, and it shows that the smallest grain size 34μm was achieved in the web of the blank.Fig.5 describes the evolution of austenite grain size in different parts of the hot blank during an 11-pass hot rolling process.
Fig.4 Distribution of austenite grain size in the hot blank Fig.3 Temperature distribution in the hot blank after 30s inter-pass interval Fig.5 Evolution of grain size in the hot blank during multi-pass rolling Fig.6 Comparison of rolling force between measured and computed values 5.
Spreadsheet Modeling of Grain Size Evolution during Rod Rolling [J], ISIJ International, 1996, 36 (6): 720-728

With the increase of shearing deformation, number of rheological ferrite increase, and become more slender.
Different finishing section of the sampling and sample numbers shown in Figure 1.
Fig.4 and Fig.6 show that the deformed ferrite grain boundaries is obvious jagged, with a large number of deformation and dislocation in the grains, and now its grain thickness takes about 200μm and the maximum grain diameter is approximately 1000μm.
At this point, the grain boundary is still showing obvious jagged, grains with a large number of deformation and dislocation.
Therefore, a number of small thin dynamic recrystallization grains germinate due to the dynamic recrystallization of the energy condition is achieved for high energy storage in the strip surface.