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The base powder used is laser form ST 100, a ferrous powder with a binder with a grain size of 20 microns.
Selection of slice thickness also depends on the grain size of the powder selected for manufacturing.
It is observed that the maximum wear is undergone with the specimen number 6 and the least by the specimen number 2.
The wear rate is influenced by a number of factors, particularly by the alloy composition, the grain size and the process parameter used for manufacturing it.
Conclusions A number of components were manufactured using selective laser sintering with different process parameter combination as determined by Taguchi method to optimize the number of experiment involved in this costly setup.

When grain sizes of granular porous media are almost the same, pore sizes of it are basically identical.
In many manufacturing processes, such as grain drying and storing, effective thermal conductivity of granular porous media is needed.
The number of dimensionless number can be obtained by looking up the table of Gauss error function.
When Gr×Pr<103 (Gr is grashof number, Pr is prandtl number), natural convection heat transfer in the pore should also be ignored [12].
The number of grid is 250×250.

A major limitation to the process lies in the formation of stray grains which can originate either from heterogeneous nucleation ahead of the solidification front or from remelting of dendrite arms due to local solute enriched liquid flow, .i.e fragmentation.
Special features related to the microstructure control during E-LMF have been studied by Mokadem et al. [5] such as off-axis dendritic growth, growth competition of grains of different orientation and cellular dendritic growth where secondary branches are missing.
From a microstructural point of view, with increasing laser beam velocity, spurious columnar grains tend to increase in number and concentrate in the [010/010] growth direction transition, i.e., in the centre of the melt pool.
This is particularly the case at 100 mm/sec where a large fraction of misoriented columnar grains fills almost all the central area.
Conclusion Microstructure control is of primordial importance in E-LMF in order to avoid the appearance of any spurious grains in the melt pool.

HAZ near fusion zone is comprised of martensite structure, while the grain size is much smaller than that in FZ.
During cooling of weld metal, the liquid firstly transformed to columnar β grains.
Rapid cooling of the transformed β grains resulted in formation of martensite in the FZ.
Fig. 4 Longitudinal residual stress (σy) of welding joint after UIT with different impact numbers Microhardness.
HAZ near fusion zone is comprised of martensite structure, while the grain size is much smaller than that in FZ.

The yield strength improvement was attributed to (i) load-bearing effects due to the presence of carbon short fiber reinforcements; (ii) grain size refinement due to the large extrusion deformation; (iii) generation of dislocations to accommodate CTE mismatch between the matrix and the particles.
Punch Preform Heater Die Sealing Plate N2 Melt magnesium Pump Crucible Gas line Fig.3 Illustration of experimental setup Observation of macrostructure characterization Microstructure characterization studies were conducted on metallographically polished extruded composite samples to investigate morphological characteristics of grains, reinforcement distribution.
(d) Grain refinement of the Mg matrix produced during severe extrusion deformation increases the number of grain boundaries present to act as barriers to dislocation motion.
Earlier study has shown that magnesium strength is highly sensitive to its grain size. 50 350 300 200 150 100 250 4321 5 0 10%Csf/AZ91D AZ91D Tensile stress, MPa Strain, % Fig. 5 Representative tensile stress-strain curves of monolithic AZ91D and 10%Csf/AZ91D 5 10 15 210 240 270 300 330 360 390 1.5 2.0 2.5 3.0 Ultimate tensile strength, MPa Volume fraction of short carbon fibers Elongation Elongation, % UTS Fig.6 Effect of the volume fraction of short carbon fibers on mechanical properties of Csf/AZ91D at room temperature Table 1 shows mechanical comparisons of Csf/AZ91D composites fabricated by different process.

Hence, a big number of studies are focused on development and investigation of heat resistant steels with improved long-term strength and creep resistance [1-6].
The mean distance between the high angle grain boundaries (HABs) is about 5 mm.
The product swDg.b. 2.6 ´ 10-22 m3/s, where Dg.b. is the grain boundary diffusivity, w is the width of grain boundary, s is the factor of segregation (it is equal to unity), was found by interpolation of experimental values of diffusivity for grain boundary diffusion of tungsten in low carbon chromium steel at 650°С [23].
Ardell, On the Coarsening of Grain Boundary Precipitates, Acta Metall. 20 (1972) 601-609
Pokorna, Grain Boundary Diffusion of W in Fe-Cr Ferritic Alloys, Scripta Mater. (1995) 289-294

The agriculture is well-developed in Jiangxi Province, grain planting area is 5300 acres and grain total output is 360.68 billion catties, as a big agricultural province with 4% of national grain is provided by the 2.5% of national agricultural acreage [10], so its grain safety is important, but residual organochlorine brought challenge to the safety.
Study on the residual DDTs level in grain of Jiangxi Province is in favor to understand its grain safety level.
According to the area and grain output of each city, the uniform grid method is used to determine the number and distribution of samples, specific sampling points are located by GPS.
Although the residues are all lower than the allowable value of national hygienic standard for grains, the detection rate all are 100% and at a certain extent healthy risk, attentions should be paid on it.
Table 3 Residual DDT overall statistic of early rice and late rice Varirties Average residual (μg/kg) Standard deviation(μg/kg) coefficient of variation(%) Early rice 64.929 49.885 76.83 Late rice 84.182 51.568 61.26 Fig. 1 Residual DDT of early rice and late rice in different regions The analysis of DDT’s sources in early rice and late rice According to the existing researches, there are three source approaches of DDTs: the first is root uptake, the DDT in the rice root soil can be absorbed by rice, and migrate to the grain; the second is pore absorption, DDTs in the air and sorbs in atmospheric particles are absorbed by rice through pores of rice leaves, then migrate to the grain; the third is plants surface absorption, DDT in soil particles are absorbed to rice surface, at last transported to grain [13].

The microstructure especially the size, shape, number and distribution of precipitate, together with the strain hardening exponent n value at different strain range during plastic deformation of the Al-0.9Mg-1.0Si-0.7Cu-0.6Mn alloy sheet, subjected to different heat treatment were investigated.
(1) Where: N= the number of data sample, i.e., the selected calculating strain point number from the calculating strain range, and N≥10, εi= the instantaneous true strain relevant to the calculating strain point, and σi= the instantaneous true stress relevant to the calculating strain point.
Afterward, as the deformation of the alloy sheet increasing continuously caused by the multiplication and slipping of dislocations, the dislocations interacts and tangles with each other, or interacts with the alloy-phase particles and grain boundaries in the matrix of alloy sheet.
As the strain of T4 alloy sheet approaches 20%, the flow stress is close to the fracture stress of alloy sheet, the initiation of micro cracks from high stress concentration zone, such as the cell walls of dislocation substructure or the dislocation accumulation groups at the grain boundary or in the front of the big alloy-phases is the main reason for the further descending of stage strain hardening exponent ns and the macro strain hardening effect of T4 alloy sheet.
After the plastic deformation exceeds 1% due to much more dislocation glide, new dislocations are created by tensile load and must interact with both those dislocations and the precipitates or grain boundary already existing in the matrix of alloy sheet, which cause the dislocation tangling and dislocation accumulation groups at the grain boundary or in front of the precipitates.

Numerous micrographs from these specimens were analyzed in terms of more than twenty microstructural parameters describing grain size, shape and orientation.
Despite the significant number of parameters available, the smallest scatter between experimentally determined and predicted fatigue strength was reached if only the grain size was considered according to the following equations: (1) (2) (3) Here, S denotes the standardized fatigue strength parameter and ECD is the equivalent circle diameter determined from the micrographs.
This relation between grain size and fatigue strength was implemented into Deform™, thereby allowing the determination of the local fatigue strength in each node of the finite element model.
Also, these methods are sensitive to numerical noise and discontinuities of the objective function, and their performance deteriorates with increasing number of parameters.
Gradient-free methods are able to handle a higher number of parameters and show better performance in presence of discontinuities and numerical noise.

The material has almost equiaxed grains, with an average grain size of 40-50 μm.
At each strain level, the number of applied cycles, Na, was inversely proportional to the strain amplitude (Na = 150/εa), in order to have an equal damage in each step.
In fact, at low strain amplitude, only grains with favorable orientation (Schmid factor close to 0.5) will be deformed plastically.
With increasing number of cycles, the second peak dominates and the two peaks merge together.
Changes of f(σic) in α/β brass with the number of cycles indicate softening of the alpha phase and hardening or steady behavior of the beta phase in the majority of the tests.