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Recent studies identified martensite reversion between 600-800°C for austenitic steel alloys and state, that grain size plays an important role [7].
Feritscope measurements were validated by X-ray crystallography measurements and is seen as reliable as long as a sufficient number of measurements are performed [14].
Micrograph in Figure 6 shows typical twins and grain boundaries after pre-straining.
Higher temperature levels beyond 1100°C are leading to coarse grain formation, which is not acceptable for most forming processes.
Annealing at 800°C must be avoided due to formation of carbides as well as at 1100°C to avoid coarse grain.

Generally speaking, the cast ingot comprises very coarse grains with an average size of 147 mm, as shown in Fig. 1 (a).
Obviously, a large number of Fe-rich intermetallic and Al(FeMn)Si phases and other particles (such as Mg2Si, Q phase, excess Si particles and Mn-bearing dispersoids) distribute in the ingot.
After homogenization, Fig. 1 (b) shows that the ingot also comprises coarse grains with an average size of 151 mm.
It can be seen from Fig. 1(h) that the short time homogenization has almost no effect on grain size change.
Recrystallized grains were observed after annealing treatment, and the particles also grew much more (as shown in Fig. 1(e)).

These microstructural elements range several orders of magnitude in size from several microns (prior austenitic grain) to nanometer (secondary hardening carbides).
So, NMI and lath boundary initiation proportion decreases with increasing test temperature whereas the grain boundary initiation increases.
Thus, the martensite laths which are located within the grains of the initial austenitic structure can be observed; a grain decohesion seems to appear and an intergranular crack initiation could be suggested [17-18].
Hence, loading conditions related to number of cycles to failure can be discussed.
Fatigue resistance is determined by the material lifetime through the number of cycles to failure.

Mesolevel element is the polycrystal grain - a crystal with a nearly perfect crystal structure and the corresponding elastic and plastic properties.
One of the major problems of building models of crystal plasticity is to identify and verify a large number of optimal parameters.
In order to describe the phenomenon of hardening, it is necessary to consider the interaction of dislocations during sliding, as well as the interaction of dislocations with other defects, such as grain boundaries [5, 6].
Conversely, the greater the number of different systems which are involved into the deformational process, the closer this factor is to the zero value.
Dependence of the value of target function and the number of iterations.

The results showed all the as-prepared Ce-V/TiO2 catalysts were made up of nanometer grains.
A number of researches deal with the effects of support and preparation methods for vanadium supporter catalysts [11-15].
Compared with Fig. 3(b). the grain sizes of 10wt%V/TiO2 catalysts was smaller (about 100nm), and the grains appeared rod-like (diameter=10-50nm,length=100-150nm), because radius of V 5+ and Ti4+ are almost equal , for V 5+ it is easy to get into the inner part of TiO2 crystal lattice, resulting in the formation of V3Ti6O17 complex oxides.
The grain of 5wt%Ce-10wt%V/TiO2 catalysts still displayed nanometer rod-like, but the grain sizes were much smaller (Fig. 4(b)).
The Ce loading made the grain sizes of catalyst much smaller, and these catalysts were composed of nanometer granule, possessing large quantity of surface micropore, high adsorbability and enlarging area of contact with reactant.

Their research results show that the introduction of Ti5Si3 in TiAl intermetallic can prevent the movement of the grain boundaries, restrain the growth of grains, and improve its mechanical properties obviously.
Ti(wt. %) Al(wt. %) Si(wt. %) Theoretical target Ti5Si3 content (wt. %) TS 0* 64 36 0 0 TS 1 64.1 35.64 0.26 1 TS 3 64.3 34.92 0.78 3 TS 5 64.5 34.2 1.30 5 TS 7 64.71 33.48 1.82 7 TS 9 64.91 32.76 2.33 9 TS 12 65.21 31.67 3.12 12 TS 15 65.51 30.59 3.90 15 *TS X refers to the sample number, and X is the targeted weight per cent of Ti5Si3 phase Fig.1 XRD patterns for TiAl/Ti5Si3 composites with different contents of Si.
The in situ formed Ti5Si3 particles decreased the matrix grain size apparently, which is illustrated to be beneficial to improve the strength.
This indicated that the introduction of small quantities of in situ formed Ti5Si3 can improve the fracture toughness due to the dispersion of fine grain sized ceramics particles.
(2) The addition of Si reduced the matrix grain size obviously, and as a result, the mechanical properties were reinforced.

The number of cycles to failure was recorded for each specimen, and 3 to 6 experiments were performed at each stress level depending on the quality of the weld.
Figure 1 Specimen preparation from the welded plates Results and Discussion Microstructural analysis revealed coarse grains with average grain diameters of approximately 113.1 µm in the SA-GMAW welds (fig. 2a) and 56.9 µm in the FA-GMAW welds (fig. 2b).
The unwelded 5083-H11 plate material displayed a much finer grain size with an average grain diameter of 24.0 µm.
This hardness reduction can probably be attributed to grain growth and microstructural changes during the weld thermal cycle.

These high demands are also met by the micro-alloyed steels which contain a defined number of alloying elements which create strengthening precipitates.
In the case of common steels size of their grain together with precipitating phases layout do not have such a big influence on the resulting attributes.
The chemical analysis, consisting of low levels of carbon and manganese, has precise addition of grain refiners such as niobium, titanium or vanadium.
Additionally, the recrystallization of primary deformed grains and mild coarsening were observed (Fig. 4.).
The desk shape carbides forming, partially bainitic transformation suppressed the grain coarsening effect.

Ni base alloy ceramic composite coating is a mechanic disordered composite [3], a large number of ceramic grains are distributed in ductile matrix.
The thermal inconsistent strain can be determined by )0,0,0,α,α,α( 332211 ∗∗∗ ∗ =α (1) and T∆−=== )( 01 33 22 11 ααααα (2) According Eshebly-Mori-Tanaka method [5,6], the equivalent eigen strain ε* of one ceramic particle produced by the difference of thermal expansion coefficient between Ni base alloy and ceramic particles is ])(~[])([ * 1 1 α ε ε ISLLLISL −∆+∆+−∆−= − ∗ (3) Here, ∆∆∆∆L = L1 − L2, S is Eshebly tensor, I unit tensor, ε~ the disturbance strain aroused by mutual action between ceramic particles and Ni base alloy as well as ceramic grain and ceramic particle.
The average stress in Ni base alloy matrix shown in Eq.4 can be transformed to σσσσ (0) = -f L 0 ( S - I ) (εεεε * +αααα * ) (14) Substituting Eq.10 into Eq.14, we obtain longitudinal average residual stress in Ni base alloy T fA A ∆−       + − − ++ − −= )()1( )1(4 316 )1( 1 01 0 2 0 0 1 0 0 )0( 11 ααλ ν ν ν ν σ (15) and transverse average residual stress n Ni base alloy T fA A ∆−+       + − − ++ − −== ))(()1( )1(4 316 )1( 1 01 00 2 0 0 1 0 0 )0( 33 )0( 22 ααµλ ν ν ν ν σσ (16) Experimental For Ni base alloy WC grains composite coating, and the thermal cycle temperature between 15°C and 650°C, the thermal expansion coefficients and elastic modulus of Ni base alloy and WC grain are λ0 = 225.75 GPa, µ0 = 604.34 GPa, λ1 = 500 GPa, µ1 = 1560 GPa, ν0 = 0.3, f = 0.25, α 0 = 14.5 × 10 −6/°C, α 1 = 11.03 × 10 −6/°C.
Substituting the thermal expansion coefficients and elastic modulus of Ni base alloy and WC grain into Eq.15 and Eq.16, We have MPa74.169 MPa,12.224 MPa,75.60 )0( )0( 33 )0( 22 )0( 11 −= −== −= mσ σσ σ Using experimental result, we get MPa169 )0( −=mσ .

The eutectic has predominantly fine grained structure, only in some places there was observed lamellar eutectic.
The cracks spread along the grain/phase boundaries.
The oxidized surface of material was completely decomposed – the material lost cohesion through the grain boundaries and eutectic areas (see Fig. 9).
Fig. 8 – The detail of pores and shrinkages in the material of bottle wall Fig. 9 – The detail of decomposed oxidized surface of material – the material lost cohesion through the grain boundaries and eutectic areas Fig. 10 – The EDX analysis of decomposed area and intact material Discussion The oxidized layer with approx. 200 µm thickness was observed on both sides of bottle wall.
The number of cracks and the degree of material decomposition are more significant on the bottle wall side without surface protection (unpainted side).