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The results indicated that the specimens with fine grains (30µm) own the longest fatigue lives than those with intermediate (80µm) and coarse grains (210µm).
The fatigue stress amplitudes of the specimens increased with the grain refinement, although the fatigue lives of the specimens with intermediate and coarse grains were close.
Effect of grain size on fatigue life Three different grain sizes of 316LN stainless steel are obtained by solution treatment at different time and different temperature.
Effect of grain size on the slip bands and crack initiation.
From Fig. 5, it is easy to find that the larger the grain size, the more the number of crack initiation and persistent slip band, under the same strain amplitude.

Introduction The occurrence of variant selection during the transformation of austenite into martensite/bainite in steels and in Fe-Ni alloys has been extensively studied and a number of models, e.g. [1-3], have been proposed to account for this phenomenon.
However, the texture obtained in this way can more precisely be referred to as a "microtexture" and its comparability with the macrotexture will depend on the number of actual grains covered by the scan.
Outlines of prior-austenite grains can be deduced from the orientation differences of one grain with respect to its neighbors.
One such γ grain is illustrated in Fig. 3.
The contour lines link points that represent the same number of orientations per specified volume (0.0207×0.0207×0.0207) of R-F space.

Journal Title and Volume Number (to be inserted by the publisher) 3 It is important to know the characteristics of the environment that surrounds the critical nuclei, in other words, the orientation of the matrix grain and, especially, the misorientations around the nuclei.
It is expected that deformed grains of low pattern quality consist of a larger number of smaller subgrains than that of high pattern quality grains.
Shear and transition bands generate considerable grain fragmentation leading to relatively abrupt changes of orientation in space, or steep short range Journal Title and Volume Number (to be inserted by the publisher) 5 orientation gradient besides high stored energy due to strain localization.
But its volume fraction in the deformed microstructure is extremely small inevitably leading to a small number of nuclei.
In addition, because the deformation behavior of a grain is also affected by the neighboring grains, the consideration on the orientation of neighboring grains may also be necessary.

This process was repeated until the desired grain size was reached; this was commonly found around 200 µm.
Figure 2: Faceted near-sigma 7 CSL type grains in an HPAl+Zr alloy annealed at 350°C taken at different times to show the growth of recrystallized grains.
Acknowledgments Support is gratefully acknowledged from the Alcoa Technical Center and by the MRSEC program of the National Science Foundation under Award Number DMR0079996.
Humphreys: in Recrystallization and Grain Growth, G.
Shvindlerman: Grain Boundary Migration in Metals: Thermodynamics, Kinetics, Applications (CRC Press, 1999). 7.

Otherwise, the grain growth was inhibited.
The liquid phases of Ba6Ti17O4 and Ba2TiSi2O8 promoted grain growth due to high solution of BaTiO3 grains in the liquid phases.
In the literature [6], it is suggested that the grain size is the most smallest in BaTiO3 ceramics (x=2.0) since a large number of such seed grains formed during recrystallization in the final stage have little chance of growing to big grains.
However, BaTiO3 grain couldn't dissolve in Ba2Ti2SiP2O13, so that Ba2Ti2SiP2O13 restrained grain growth.
Otherwise, the grains were inhibited.

Rotating bending fatigue tests were carried out for maraging steels with different grain size in moist air in order to investigate the effects of humidity, grain size and reversion austenite on fatigue strength of the steel.
Fatigue strength was decreased by humidity, and the decrease in fatigue strength was large in larger grain sized steel.
The mean grain sizes were about 21µm, 40µm and 105µm.
The decrease in fatigue strength is large with increase in grain size.
The decrease was marked in larger grain size and caused by the acceleration of crack initiation and its propagation.

Grain growth proceeded preferentially in the higher temperature region and resulted in a large grain surrounded by small grains.
Two-dimensional microstructure model was adopted for the calculation based on the algorithm of Monte Carlo method [2-3]. 200 x 200 cells were used for the description of microstructure and each cell has its own number correlated to grain orientation.
Grain boundary migration is an important and fundamental process of grain growth.
Migration process is simulated by changing the site number to that of a site randomly selected from the surrounding sites.
The hatched grains are preferentially grown grains during spot heating calculation.

akrphaneesh@gmail.com, banirudh_bhat86@yahoo.com, cquasar66@gmail.com, dktkashyap@yahoo.com Keywords: Particle size; Average grain size; Largest grain size; Zener limit; Grain size distribution; Particle fraction on grain boundaries.
Different grain growth parameters such as mean grain size, largest grain size, fraction of second phase particles lying on grain boundaries, etc., were computed for the pinned microstructures.
Simulation studies in grain growth was pioneered by Srolovitz et al and others [1 - 3] who investigated grain growth kinetics, grain size distributions, the limiting grain size, among others, in both two-dimensional and three-dimensional crystals.
Since the effective number of particles pinning the grain boundaries decrease with increasing particle size for the same surface fraction, the Monte Carlo steps required to bring about stagnation is also more.
Sahni, Computer simulation of grain growth-I.

In addition, a large number of nano-γ'' phases were precipitated on the broadened grain boundaries of the near-surface regions.
As a result, a large number of newly generated dislocations accumulated in the vicinity of the grain boundaries and twin boundaries, causing the little migration of the grain boundaries and twin boundaries, which appeared as a slight change in grain shape on the EBSD map.
As the compression energy input was absorbed by the top-surface regions, the energy that transferred to the deeper regions gradually decreased, resulting in a decrease in the degree of deformation and the number of recrystallized ultra-fine grains in this region.
There was an ultra-fine strengthening layer in the near-surface regions and the degree of deformation and the number of recrystallized ultra-fine grains decreased with the increase of depth.
In addition, a large number of nano-γ'' phases (less than 100 nm) were precipitated on these broadened grain boundaries, as shown in Fig. 5b.

- 1 - A Study on the Manufacture of Aluminum Grain Refiner by Flux Reaction M.
Studies on the grain refining ability of Al-5wt.
Fig. 5 (b) shows the effect of reaction temperature and holding time on the number of TiAl3 particles.
As you see, the number of particles tends to decrease with the holding time and reaction temperatures.
Fig. 5 (a)Size and (b)Number of TiAl3 particles as a function of holding time at the various reaction temperatures.