Search results

This size provides sufficient area for a number of indents located far from grain boundaries which may affect nanoindentation results [7].
At the same time, it still allows covering a large number of differently oriented grains by EBSD and nanoindentation in a reasonable time.
In order to obtain a reasonable statistics, a number of indents per grain ranged between 10 and 20.
All indents were located within the grain interior more than 1 μm far from grain boundaries to minimize their influence [7].
It may, however, change with increasing number of indents during the experiment due to sticking of the indented material to the indenter tip.

Ti : C+N=12 Al-killed Steel Rimmed Steel Ti : C+N=6 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 Steel B Mean r- value Steel A Large Small Grain size Occurrence of Orange Peel Fig.5 Correlation between ASTM grain size numbers and mean r-values of cold-rolled steel sheets.
progress of recrystallization, where the <111>//ND grains increased and the <100>//ND grains decreased.
Therefore, the larger number of the <111>//ND recrystallized grains in Steel B, which nucleate in the vicinity of the hot-band's grain boundaries, can provide the large grain boundary area to grow into the deformed matrix even under the same migration rate to Steel A.
In the PFZ, little fine precipitates were not observed besides the small numbers of coarser precipitates.
Coarsening of precipitates on grain boundary relieves the pinning force and gives rise to the grain boundary migration.

The TBRVE consists of a certain number of grains and orientations of the polycrystal, which conveniently represents the global texture and can capture the mechanical response of the material including the BE under cyclic loading.
It is a small volume element which contains a sufficient number of grains to model the global response of the macro-scale specimen.
The EBSD data obtained on the AA7075 specimen is imported to the MTEX toolbox [26] where the ODF is generated, and then crystallographic orientations are obtained by discretising this ODF with the grain number in the RVE as the control parameter.
Before carrying out the simulations, convergence studies in terms of grain number, grain orientation, mesh density and tessellation were conducted to obtain the appropriate RVE.
The model consists of a total number of 51840 brick elements (C3D8R), and the grain tessellations at the edges have been created to be repeatable in each direction.

For this, it is necessary to solve a number of emerging problems: analyze how the effect of heat treatment on the grain size occurs; determine the value of the factor of different grain size serving as the main criterion for the dispersion of the system as a whole, and also try to find correlation between it and the ultimate strength and coercive force of the steel under study; explain the changes occurring with the grain size factor during heat treatment.
The grain size factor is calculated by the following formula: (1) where fi – share of grain with a certain score, %; fmax – share of grain occupying maximum area on the microsection, %; Zi – grain score; Zmax – score of the grain occupying maximum area on the microsection.
Methods for identifying and determining grain size’[2].
Histogram of percentage distribution of grains by score for microsections of heat-treated specimens made of 15KHSND steel by grain size Fig. 3.
Methods of Detection and Determination of Grain Size].

First, the exponent of the inverse grain size is given by p = 2.
The alloy had an initial grain size of ~1.8 μm after annealing at 473 K for 1 h and was refined by ECAP processing for 8 passes to have a mean linear grain size of ~0.8 μm [8].
It should be noted that the tensile axis is vertical in the micrograph in Fig. 1(b) and the grains appearing white are the Zn-rich grains and the grains appearing dark are Al-rich grains.
The disk samples with a diameter of ~10 mm and a thickness of ~0.80 mm were processed under a pressure of 6.0 GPa at 1 rpm for total numbers of 4 and 5 turns in a constant rotational direction.
There is a reasonably homogeneous distribution of Zn and Al grains with an average linear intercept grain size of ~350 nm.

This AFM examination bring out the details of grain refinement and topographical roughness emerging from crystalline and microstructural properties like orientation by color contrast after etching, precipitation, deformation bands, slip lines and shear bands with progress in rolling as referred by the number of rolling cycles here.
In SPD methods, large strains refine the grain structure into ultrafine grain size (100 nm-1000 nm) or nanostructures (less than 100 nm) [1].
Further, the number of cycles can be chosen carefully to avoid cracking of material that could occur during further rolling cycles [32].
The fraction of such slipped/sheared grains increased with increasing number of cycles as observed from Fig. 3.This could be caused by simple shear forces which are predominant compared to tensile and compressive forces.
Strength can be observed to increase with increasing number of cycles while ductility decreased partially as shown in Fig. 4 c and d.

The grain refining mechanism of the carbon grain refinement is currently under disputation [4, 5].
The twins usually traverse entire grain and stop at the grain boundary.
However, the twins are finer and number of twins is larger than that in AZ31 alloy.
As mentioned above, the newly formed grains expand into the as-cast matrix by grain growth and nucleation of further grains at the grain boundaries of the growing grains.
Nucleation of new grains at grain boundaries involves formation of subgrains at grain boundary regions [6, 7].

The paper considers the problem of improving fine-grain concretes production technologies.
Materials and Methods The application of 3D-technologies creates the possibility of constructing buildings and structures of any shape or number of floors, or original architectural expressions.
Components of fine-grain concrete compositions № Number of composition Binder Type of main aggregate Fine aggregate Coarse aggregate 1 1 CEM I 42.5N Nizhneolshansk sand granite macadam 2 2 CEM I 42.5N QS crushing screenings – 3 3 CB QS crushing screenings – 4 4 CB QS crushing screenings, Nizhneolshansk sand – Prototype samples were made of the mix with the necessary content of all components, including the construction composite and the modifying admixture, which provided the optimal phase composition of hydration products (Fig. 2).
During the whole curing time a number of alterations in the material’s structure take place, due to the artificial contraction, decrease of porosity and prevention of flowing deformation.
For fine-grained concrete on a composite binder with high-density packaging, creep decreased by more than two and a half times compared to fine-grained concrete on cement.

The main advantage of such modifiers is a great number of particles per the melt volume unit.
Phase Composition and Structural State of Unmodified High-Manganese Steel The quality of railway arrow samples was evaluated in terms of austenite grains, phase composition, number, shape, and distribution of nonmetallic inclusions.
However, the MM introduction into the melt had an impact on the grain size, number and distribution pattern of nonmetallic inclusions in the railway arrow samples.
Figure 3 a shows the optical image of a modified sample, which demonstrates that the number of nonmetallic inclusions has significantly reduced both in the grain body and along the grain boundaries.
The comparison of microstructure in unmodified and modified samples by means of SEM revealed that the MM introduction significantly reduced the number of nonmetallic inclusions inside the grain and along their boundaries (Figs. 2 and 4).

Under these conditions, Ostwald ripening is the dominating mechanism of grain coarsening in the stage of high liquid fraction, in which grains continuously coarsen and the small grains gradually melt [9].
Shape factor of solid grains was calculated by applying the Eq. 1 [10]: SF= 1(1Np2/4πA)/N (1) In which A, N, and P are the area, the number of experiments and perimeter of solid particles, respectively.
Fig. 2 The effect of Ti addition on grain size.
Because of this low amount of liquid phase, it cannot soak into the grain boundries; hence, grain boundaries are not uniform and continuous.
Due to these two mechanisms, grain boundaries between adjacent grains disappear, causing larger grain with irregular shapes.