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In this study, we've used carburized-quenched-tempered steels that received shot-peening process with different shot grain sizes and evaluated variation of surface property of the steels.
Fig. 4 shows the relation between respective shot-peening conditions and Vickers number.
The inter-granular oxidation is a structure of oxygen that exists in the carburizing chamber combined with alloying element, such as Cr, Mn, etc., contained in the carburized steel, forming along grain boundaries. [2].
• The grain size is especially important and extra care must be paid for quality control of shot-peening process.

The results show that the cross-section morphology Cu6Sn5 of the solder joint interface is scallop-like and its section morphology is circle-like grain.
From the Fig.3, it shows that there are lots of circular-like and paraboloid-like compound microaggregates, and most of these grains are contected 5-7 other grains in the Fig.3, and these grains are determined as Cu6Sn5 from the atom number proportion achieved by composition analysis and the literatures [9-13].
The forming reason of Ag3Sn phase is described as below: the Ag3Sn grain can be stochastic moving at certain speed rate in the solidifying process of the solder alloy, and it maybe hit the surface of the Cu6Sn5 compound because of heat motion, and then the Ag3Sn grain will be captured by the adsorption action during soldering, because of the higher activity existed in the interface.
Surface morphology of interfacial Cu6Sn5 is circle-like grains and its cross-sections morphology is scallop-like between the Sn-2.5Ag-0.7Cu-0.1RE and the Cu substrate after soldering. 2.

The element Y is distributed mainly at the grain boundaries.
The atoms in grain boundary are looser, with more vacancies and other defects. the segregation of Y atoms in the grain boundary will reduce the free energy, which is a spontaneous process of thermodynamics, so Y atoms easy to gather in the grain boundaries, and then this cause uneven distribution of ingredients.
That’s because (1) Y can refine grains; (2) Y element increased nitrides in strengthened layer; (3) Y has solid solution hardening effect.
The reason why the wear resistance of W-Mo-Y co-diffusion and nitrided samples was much better than the samples treated by W-Mo-Y co-diffusion and nitriding was that (1) Y in alloying layer during plasma nitriding had a catalytic effect, which could promote the formation of a large number of nitrogen compounds; (2) the atomic radius of Y atoms was larger in the diffusion layer, which would cause a large distortion.
That’s because the solid solubility of Y in Fe was very low, Y distributed mainly at the grain boundaries and generated a small amount of intermetallic compound.

Although the CrMoV steel has a certain degree of reheat crack trend, it possibly happens only under coarse grain and high tensile stress whereas doesn’t happen with normal condition. 52MPa 39MPa Fig.5 Pipe-step model and its outer surface stress Table.1 Chemical composition analysis of the base metal Sample number Chemical composition（%） Element C Si Mn S P Cr Mo V Base metal near the crack 0.12 0.24 0.68 0.012 0.014 1.11 0.22 0.22 Weld seam near the crack 0.09 0.52 0.77 0.020 0.025 0.98 0.37 0.24 Metallurgical microstructure observation.
Observation showed that the crack originated at the melting line then propagated along coarse grain zone where lots of intergranular cracks were found.
Fig.6 Lots of cracks within coarse grain zone Fig.7 SEM of microcrack within coarse grain zone SEM observation.
It can be found from Fig.7 that the crack in coarse grain zone was transverse type and consists of a cluster of holes that form a macrocrack when connected.
Those cracks locate only within coarse grain zone and belong to reheat crack.

For produce a large number of micro-defects, which form large internal residual stress, it appears work-hardening and the hardness is high.
Recrystallization is a process of form new strain-free equiaxed grains through the formation and growth of crystal nuclei.
In a relatively short annealing time, although most of the residual stress within the organization has been eliminated, the recrystallization process has not completed, some of the grains still present orientation after deformation, which indicate that old distorted grains have not completely disappeared, as shown in Figure3(a).
This may be due to the increase in the size of grain with the time extended, and at the same time, the carbide that has been broken in organization began to grow up in ferrites.
It is indicate that when the sample in tension, plastic deformation is generated under the tensile stress, grains begin to slip and scalability has been greatly improved.

There is number of successful applications of fibre reinforced composites in automotive, aircraft, space and energetic industry [1-7].
The grains were approximately ten times bigger after the annealing and average grain size was around 500 nm.
Note that alumina grains are not present there anymore.
Elongated alumina grain is also marked as an example.
The main change can be seen in significant grain growth.

On this basis, developed a number of new wear-resistant steel, chromium steel, low alloy steel, carbon steel and graphite, steel, etc[4].
Figure 2-1 Metallographic organization （a）1# （b）2# （c）3# （d）4# 2 Mechanical properties and the tensile fracture morphology analysis In the process of monopodium stretching, the coarser the grain is, the greater the stress and strain concentrate.
The period of aggregative distortion is easy to generate cavity in the grain boundary, and reduces plasticity due to the cracked of grain boundary.
The material will have a greater macroscophic plasticity because the intergranule distorted coordinatly when the grain refined.
Table 4 The wear volume and relative wear resistance of the test materials, Sample number Original weight （g） After grinding weight (g) Wear (g) Relative wear resistance 1 45.2863 45.1886 0.0977 0.6028 2 45.4011 45.2663 0.1348 0.4369 3 43.8416 43.7827 0.0589 1.0000 4 42.8287 42.0272 0.8015 0.0735 Figure 3 shows room temperature, the working conditions for 50m/s - 90N - 2min sample wear morphology.We can see that the 1# and 2# sample morphology is peeling and adhesion.

The excessive growth of crystals will introduce a large number of defects in the crystal structure of Si3N4 ceramics.
Because the ionic radius decreases with the increase of the atomic number, and at the same time has a higher negative charge, it is easier to adsorb on the surface of Si3N4 crystal grains.
In the post-sintering process, due to the effect of abnormal grain growth, the product has a larger proportion of large Si3N4 grains, which in turn improves the thermal conductivity of Si3N4 ceramics.
The results show that as the ratio of Y2O3/SiO2 increases, the O content in β-Si3N4 grains decreases.
Ruhle, Influence of secondary phase chemistry on grain-boundary film thickness in silicon-nitride, Z.

Mitsubishi and Sumitomo have developed a fine-grained version of this alloy, which exhibited an improved steam oxidation resistance at 650o C and 700 o C compared to the coarse grained version [3].
Double-layered oxides formed on both coarse-grained and fined-grained TP 347 H.
A total number of 24 TP 347H FG samples was investigated.
The formation of oxides along alloy grain boundaries ahead of the oxidation front (Fig.2 and 6) suggests that the oxygen diffusion is more pronounced here than within the alloy grains and that the grain boundaries oxidise before the bulk of the grains.
The slow lattice diffusion of Cr at 500o C combined with the much faster grain boundary diffusion explains why reformation of the protective layer occurs along the alloy grain boundaries at the lowest temperatures.

This aggregate is characterised by comparable grain strength to ceramic aggregates but, on the other hand, has a relatively high absorption rate of up to 30 %.
Currently, there are a number of suppliers on the market offering lightweight porous aggregates produced by different types of technologies.
These raw materials are transformed by the technological production process into a plastic dough, which has the ability to form a porous but, on the contrary, sintered structure of individual grains at high temperatures [1].
The individual grains of Liapor are fired in a rotary kiln at a temperature of 1200 °C, which guarantees optimal aggregate properties [5].
These aggregate grains are then fired by means of a so-called self-ignition process and sorted into the desired fractions. [5] Lightweight Concrete with Agglomerated Aggregate.