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At present, it has been reliably established that the hydrogenation of wire samples made from nickel titanium based alloys leads to the degradation of their superelastic and mechanical properties (hydrogen embrittlement), regardless of the grain size [2,3].
In a number of publications the subsequent effect of aging at room temperature on functional and mechanical properties has been studied [4-6].
The wires after drawing had nanocrystalline structure with an average grain size of 86 nm dominated by qusiequiaxed grains with high-angle misorientations (Fig. 1a, b).
Microstructure (a) and grain size distribution (b) in ultrafine-grained Ti49.1Ni50.9 (at.%).

Thereby, this stable compound can only play a part in control of original austenite grain size at a high temperature.
The carbide and nitride of V almost dissolve in austenite, so they show no effect on controlling original austenite grain and delaying the recrystallization.
Finally, the solid solution and precipitation of the carbides and nitrides of Nb can be produced in austenite region, to cause fine grain strengthening and precipitation strengthening, and its strengthening effect is the largest.
Transitions such as recovery, recrystallization, and grain coarsening after recrystallization happen in this process.
The relative alloy elements can be dissolved by increasing reheating temperature, but excess coarsening grains may be produced at a higher reheating temperature, the refining effect of deformation grains is closely associated with the initial grain size, so the tinier the grain size before deformation, the larger effective grain bundary area can be obtained finally.

This is a direct method, because the recrystallized fraction can be estimated from relative area of recrystallized grains.
Fig. 3.: EBSD scan results of a partially recrystallized sample, IPF map (a.), Image Quality map (b.), recrystallized grain map by DRG software (c.)
Volume fraction of recrystallized grains computed with the default settings of DRG software [1].
Table 1. represents the number of samples, recrystallized fraction obtained by DRG software, and its deviation.
Treatment of misorientation data to determine the fraction of recrystallized grains in a partially recrystallized metal.

Inside spherical pores, the pore wall is smooth, grain boundaries are coarser than outside, the number of secondary phases in the grains is increased and the size is larger.
Single interstices distribute along grain boundaries with size of several microns to tens of microns (Fig. 2d).
Interconnected pores arise along grain boundaries with long and thin morphology (Fig. 3d).
And grain boundaries inside the gas pores are broader than outside.
The grains and intragranular precipitates around gas pores are bigger than that of interstices.

Analysis of Theory When calculating true contact length, three factors should be considered: (1)geometric contact length, (2)deformation contact length and (3)grain contact length of the surface roughness effect.
The equation of microcontact theory is expressed as: (14) (15) f1(e)= (16) (17) (18) (19) where β=ηReRq with η representing the peak number on an unit area, Re is the composite surface curvature radius of peak and Rq is the composite square root of surface roughness.
‘Curvature radius of peak’ refers to the radius of the wheel grains in grinding.
Under the same values of Re and Rq, different value of β represents different number of wheel grains in a unit area.
In other words, the higher is β, the denser is the grains in a unit area.

Within interdentritic areas metal obtain its grain structure, which is typical of an average ≈ 20 ± 3.36 µm nickel-chrome austenite (Fig. 3, a).
Grain structure becomes more expressive, and an average grain becomes 1.5 times smaller and makes ≈ 12 ± 0.57 µm.
Heat-affected zone in both cases has a polyhedral grain structure, typical of a nickel-chrome austenite (Fig. 3, c, d).
Some grains contain twins.
Within a heat-affected zone of a welded joint, made with the help of an inverter converter, an average grain makes less than ≈ 30 ± 6.28µm, with a higher twinned degree of grains (Fig. 3, d).

Steel balls diamater used in this research was about 0.6 mm with hardness number of 40-50 HRC.
Therefore, it is important to improve hardness number of surface layer of the mechanical component.
The Vickers hardness number was calculated using reference [5].
Hardness number of surface layer is bigger than that of the centre due to smaller grain size as shown in Figure 6. 105 μm Raw material area Shot peening effect area Fig 6.
Hardness number of shot-peening treated AISI 304 is 495.89 VHN, and hardness number of AISI 316L is 384.91 VHN.

Inclusions of β grains are also seen with average grain size of 10µm (range of 5µm-20 µm).
The Co binder is uniformly distributed and WC grains have sizes varying from 1 to 5 µm.
Also, we see that the WC grain size is close to that of the Ti-555 alloy grains.
Turning is a manufacturing process with a large number of interacting variables.
Ti-555 has a nodular structure with very fine grains of about 1μm with a much harder phase β.

An effect of the grain size on the kinetics, completeness, and position of critical points of martensite transformation in steels is known [1, 2].
They were studied in coarse-grained (CG) and nanocrystalline (NC) condition.
Grain size of CG iron was about 500-1000 μm with low density of dislocations.
The nanostructure with grain size down to 60 nm was produced by high pressure torsion (HPT) technique [13-15].
The structural parameters were: the average crystallite size is about 60nm, Fig. 2; dislocation number density of crystallites is low (i.e., they are almost dislocation-free); mutual misorientation angles of the crystallites are at least 15°.

The method allows for revealing simultaneously open-micropipes, polytype inclusions, low grain boundary regions, and non-uniform resistivity.
Despite the obvious progress in SiC growth, there is still a number of factors, which hinder SiC from achieving its real commercial potential.
Porous SiC (PSC) has been around as an object of interest for a number of years, since its ability of going beyond conventional applications of SiC and developing new technologies for wide band gap semiconductor-based electronics has been demonstrated.
Results and Discussion Currently, there exist a number of methods for defect inspection in SiC wafers.
Images of anodized SiC substrates, which were obtained with the use of commercial optical scanner: (а); area containing micropipes, (b); polytype inclusions; (c); grains with low-angle boundaries, and (d); doping non-uniformity in 2 inch wafer; (e) an optical microscopy image of the PSC surface subjected to the treatment in KOH melt.