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Grain Boundary Engineering of High-Nitrogen Austenitic Stainless Steel H.
During welding, an HNSS is ready to precipitate rapidly immense amounts of chromium nitride in the HAZ, as intergranular or cellular morphologies at or from grain boundaries into grain interiors [9].
Recent grain boundary studies of austenitic stainless steels have revealed that the sensitization depends strongly on grain boundary structure, and that low energy grain boundaries such as CSL boundaries have strong resistance to intergranular precipitation and corrosion [14,15].
In contrast, the GBEed HNSS having a very high CSL frequency (87 %) shows a small number of isolated random boundaries surrounded by many CSL boundaries as shown in Fig. 2(b).
During the thermomechanical-processing, a migrating grain boundary inevitably interacts with lattice dislocations and other grain boundaries.

Grain growth.
The discretized grains are used for the calculation of the mean grain size, µ, and the grain size distribution in the form of standard deviation, σ.
Systematic errors are often an issue, and for the complicated field of temperature measurements there was a feeling that this field would be no exception dealing with emission numbers, wall temperatures, surface temperatures etc.
The results reliability improves as the number of coils fed into the ANN are increased and the model results are very dependent upon accurate temperature measurements and that this is a complicated field, especially for stainless steel and aluminum where emission numbers can be difficult, the RMS error is low and model accuracy is high.
Since the model discretization deals with time steps and not with individual grains, each time step represents the average grain size for this time increment and the grain growth is the increase of average grain size for the time increment and not for the individual grain.

According to our research, we conclude that, the existence of a large number of twin, twin boundary, fault and the grow up grain are the main factor of the improvement of the electrical performance; and the existence of twin, stress concentration holes and fault are the key to improve its mechanical properties.
Also, we observed the grain growth phenomenon.
It clearly shows the quasi-static grain.
A large number of vacancy defects form in the process of atomic plane slip.
After LSP, the hardness and elastic modulus of the nanometer copper film increase by 38.5 %, 45.2 %, respectively; 2) The existence of a large number of twin, twin boundary, fault and the grain growing up are the main factor of the improvement of the electrical performance.

The subsequent electropulse treatment furthers transformation of the grain structure since grains arise and grow due to evolving local dynamic recrystallization and partial transformation of the dislocation substructure and occurrence of a great number of microtwins.
Besides the above dislocation substructures there are grains (25-30% of the total number of grains) with a few dislocations.
The letter A points at the grain with a low scalar density of dislocations.
The grain structure is transformed – grains arise and grow due to the evolving local dynamic crystallization.
The further electropulse treatment is the reason for grain structure transformations since grains arise and grow due to the evolving local dynamic recrystallization and partial change in the dislocation substructure, as well as because of a great number of micro-twins.

From the zinc diffusion profiles were deduced the volume diffusion coefficient and the product δDgb for the grain-boundary diffusion, where δ is the grain-boundary width and Dgb is the grain-boundary diffusion coefficient.
However, in spite of a number of previous works on zinc diffusion, oxygen diffusion, and defects in ZnO, there is still lack of conclusive data about defects and diffusion in this material.
Determination of the grain-boundary diffusion coefficient.
The authors of the present work have performed a limited number of measurements of zinc diffusion coefficients in Al-doped ZnO in order to obtain information about the zinc diffusion mechanism in ZnO.
Fundamentals of Grain and Interphase Boundary Diffusion.

Figure 1a shows the number of cycles needed to form a PSB and demonstrates that the number of cycles is the higher the lower the stress amplitudes are.
Fig. 1a Stress amplitude and number of cycles needed to form a PSB.
In addition, the increasing number of grains containing PSBs was observed continuously and is also plotted in Fig. 2.
The other lines in Fig. 2 indicate examples, when 5%, 10%, 30% and 100% of the grains were covered by PSBs at higher numbers of cycles.
Cracks even 50 µm apart from the surface and also interior grain-boundary cracks as well as fragmented internal grain boundaries and dislocation wall structures could be observed [4].

In the process of grain refinement through phase transformation, driving force and the parent phase grain size are two key factors.
From this Figure, there are some austenite grains with the grain size about 3~6μm and the other austenite grains are pretty small, the mean grain size of all the austenite grains is about 1~3μm.
The number of quenching cycles also affected the austenite grain size.
Most of the observed areas were filled with the equiaxed ultrafine grains whose grain size is less than 0.3μm.
The ultrafine grains are surrounded by clear grain boundaries.

In this paper, a deformation test method to reproduce, on a laboratory scale, the microstructure evolution of aluminium alloys occurring during industrial forming processes with a limited number of tests is presented.
Another requirement for the testing method was to cover the parametric ranges of industrial forming processes such as rolling, forging and extrusion and, at the same time, to allow the analysis of varied conditions within a limited number of specimens.
No nucleation of new grains was observed.
Summary and Conclusions An innovative test method was developed to reproduce different deformation conditions with a limited number of tests.
strain, strain rate and temperature) with a small number of specimens (8 for each alloy).

Introduction Since fatigue life is usually controlled by crack growth life, there are a number of reports on the crack growth behavior of conventional grain-sized metals, whereas little has been reported on crack growth of ultrafine grained (UFG) metals.
Fig. 1 Microstructure of the material. 105 106 107 100 150 200 250 Number of cycles to failure Nf Stress amplitude σa MPa □:Coarse grain ●:Ultrafine grain Fig. 2 S-N diagram.
At this stage, a number of microcracks formed from PSB-like SBs are distributed ahead of the major crack tip.
Zhang [8] conducted fatigue tests of UFG aluminum alloy (grain size: 0.4 µm).
At this stage, a high number of shear cracks from PSB-like SBs form around the crack.

Although surface hardness of SFAP is decreasing with grain size number increasing, surface hardness of SFAP in different grain size is no evident distinction.
While in the same 65 wt% abrasive weight percent, Young's modulus of SFAP is decreasing with grain size number increasing, as Fig.11 shows.
It because that bond strength between abrasives in SFAP is decreasing with grain size number increasing, so it influences the Young's modulus of SFAP.
SFAP of 50 wt% abrasive had more bonding material and a small number of pores.
And with the same abrasive weight percent, shearing strength of SFAP is decreasing along with grain size number increasing.