On the stability of grain structure with initial Weibull grain size distribution

ABSTRACTIn this work, aluminum weld beads were deposited on aluminum plates of commercial purity (12.7 mm thick), using an ER-5356 filler wire. The aim of the experiments was to assess the effects that yield the induction of an axial magnetic field (AMF) during the application of the weld beads using the direct current gas metal arc welding process (DC-GMAW). An external power source was use to induce magnetic fields between 0 to 28 mT. The effects of the magnetic fields were assessed in terms of the macrostructural features of the deposits, morphology of the grain structure, grain size and grain size distribution in the weld metal. Macrostructural characteristics of the weld beads revealed that increasing the intensity of the magnetic induction to produce a magnetic field above 14 mT, leads to a significant loss of feeding material and there is a tendency of the deposits to increase their width and reduce penetration. Perturbation of the weld pool induced by the application of the AMF noticeably modified the grain structure in the weld metal. In particular, for the intensities of 5 and 14 mT, columnar growth was essentially non-existent. Grain size distribution plots showed, generally speaking, that the use of magnetic fields is an efficient method to produce homogeneous grain structures within the weld metal. Finite element analysis was used to explain the weld bead geometry with the intensity of the magnetic field.

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The Influence of Grain Size Distribution on the Hydraulic Gradient for Initiating Backward Erosion

Water ◽

10.3390/w12092644 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2644 ◽

Cited By ~ 1

Author(s):

Willem-Jan Dirkx ◽

Rens Beek ◽

Marc Bierkens

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Laboratory Experiments ◽

Hydraulic Gradient ◽

Concentrated Flow ◽

Pipe Formation ◽

Novel Method ◽

Flow Through ◽

The Stability

Backward erosion by piping is one of the processes that threaten the stability of river embankments in the Netherlands. During high river stages, groundwater flow velocities underneath the embankment increase as a result of the steepened hydraulic gradient. If a single outflow point exists or forms, the concentrated flow can entrain soil particles, leading to the formation of a subsurface pipe. The processes controlling this phenomenon are still relatively unknown due to their limited occurrence and because piping is a subsurface phenomenon. To study the initiation of piping, we performed laboratory experiments in which we induced water flow through a porous medium with a vertically orientated outflow point. In these experiments, we explicitly considered grain size variations, thus adding to the existing database of experiments. Our experiments showed that the vertical velocity needed for the initiation of particle transport can be described well by Stokes’ law using the median grain size. We combine this with a novel method to relate bulk hydraulic conductivity to the grain size distribution. This shows that knowledge of the grain size distribution and the location of the outflow point are sufficient to estimate the hydraulic gradient needed to initiate pipe formation in the experiment box.

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EXPERIMENTAL EVALUATION OF STEREOLOGICAL METHODS FOR DETERMINING 3D GRAIN SIZE AND TOPOLOGICAL DISTRIBUTIONS

Image Analysis & Stereology ◽

10.5566/ias.v19.p91-97 ◽

2011 ◽

Vol 19 (2) ◽

pp. 91 ◽

Cited By ~ 6

Author(s):

Guoquan Liu ◽

Haibo Yu

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Experimental Evaluation ◽

Single Phase ◽

Experimental Methods ◽

Grain Structure ◽

Serial Sectioning ◽

Topological Parameters ◽

Selection Of

The conventional serial sectioning analysis and a set of modern stereological methods, including disector, selector, point-sampled intercepts, point-sampled area, and their combinations, have been used in this paper to measure the grain size, grain size distribution, topological parameters and their distributions in a spacefilling single-phase grain structure of steel. The results from different methods are compared and used to evaluate the methods quantitatively, based on which some suggestions will be given for selection of experimental methods in materials stereology research.

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Statistical analysis of the parameters and grain size distribution functions of single-phase polycrystalline materials

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2020-86-4-39-45 ◽

2020 ◽

Vol 86 (4) ◽

pp. 39-45

Author(s):

S. I. Arkhangelskiy ◽

D. M. Levin

Keyword(s):

Grain Size ◽

Distribution Function ◽

Size Distribution ◽

Grain Size Distribution ◽

Single Phase ◽

Distribution Functions ◽

Grain Structure ◽

Polycrystalline Materials ◽

Grain Sizes ◽

Average Grain Size

A statistical analysis of the grain size distribution is important both for developing theories of the grain growth and microstructure formation, and for describing the size dependences of various characteristics of the physical and mechanical properties of polycrystalline materials. The grain size distribution is also an important characteristic of the structure uniformity and, therefore, stability of the properties of the products during operation. Statistical Monte Carlo modeling of single-phase and equiaxed polycrystalline microstructures was carried out to determine the type of statistically valid distribution function and reliable estimates of the average grain size. Statistical parameters (mean values, variances, variation coefficient) and distribution functions of the characteristics of the grain microstructure were obtained. It is shown that the distribution function of the effective grain sizes for the studied polycrystal model is most adequately described by γ-distribution, which is recommended to be used in analysis of the experimental distribution functions of grain sizes of single-phase polycrystalline materials with equiaxed grains. The general average (mathematical expectation) of the effective grain size (projection diameter) with γ-distribution function (parameters of the distribution function are to be previously determined in analysis of the grain structure of polycrystalline materials) should be taken as a statistically valid and reliable estimate of the average grain size. The results of statistical modeling are proved by the experimental data of metallographic study of the microstructures of single-phase model and industrial materials with different degree of the grain structure heterogeneity.

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Grain sorting effects on the formation of tidal sand waves

Journal of Fluid Mechanics ◽

10.1017/s0022112009006387 ◽

2009 ◽

Vol 629 ◽

pp. 311-342 ◽

Cited By ~ 23

Author(s):

TOMAS VAN OYEN ◽

PAOLO BLONDEAUX

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Fine Fraction ◽

Sand Wave ◽

Flat Bottom ◽

Sand Waves ◽

Sand Mixture ◽

Sea Bed ◽

The Stability

A model is developed to investigate the process which leads to the formation of sand waves in shallow tidal seas characterized by a heterogeneous sea bed composition. The main goal of the analysis is the evaluation of the effects that a graded sediment has on the formation of the bottom forms and the investigation of the sorting process induced by the growth of the bottom forms. The analysis is based on the study of the stability of the flat bed configuration, i.e. small amplitude perturbations are added to the flat bottom and a linear analysis of their time development is made. For an oscillatory tidal current dominated by one tidal constituent, the results show that the graded sediment can stabilize or destabilize the flat bottom configuration with respect to the uniform sediment case, depending on the standard deviation σ* of the grain size distribution and on the ratio between the horizontal tidal excursion and the water depth. For moderate values of , i.e. values just larger than the critical value for which the sediment is moved and sand waves appear, the presence of a sand mixture stabilizes the flat bed. On the other hand, for large values of , the mixture has a destabilizing effect. In both cases the effect that a sand mixture has on the stability of the flat bed configuration is relatively small. Moreover, for moderate values of , the fine fraction of the mixture tends to pile up at the crests of the bottom forms while the coarse fraction moves towards the troughs. For large values of , the grain size distribution depends on the value of σ*. The results are physically interpreted and provide a possible explanation of the apparently conflicting field observations of the grain size distribution along the sand wave profile, carried out in the North Sea.

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The Role of the Nd/Zn Ratio on the Stability of Mg-Zn-Nd Clusters and the Evolution of Texture in Two Mg-Zn-Nd Alloys during Annealing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.542 ◽

2016 ◽

Vol 879 ◽

pp. 542-547

Author(s):

Mehdi Sanjari ◽

Amir Rezaei Farkoosh ◽

Abu S.H. Kabir ◽

Jing Su ◽

In Ho Jung ◽

...

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Early Stage ◽

Texture Evolution ◽

Reduction Rate ◽

Grain Coarsening ◽

Weight Percentage ◽

Basal Pole ◽

The Stability

Texture evolution in two magnesium alloys, Mg-4%Zn-1%Nd and Mg-1%Zn-1%Nd (weight percentage), was studied after rolling and the subsequent isothermal annealing. The finish rolling was completed in a single pass with a thickness reduction rate of ~30% at 100 °C and a rolling speed of 1000 m/min. After cooling to room temperature, the rolled samples were annealed at 350 °C for different annealing times. Upon annealing, the maximum intensity of the basal pole texture decreases as recrystallization progresses. In the Mg-1Zn-1Nd alloy (with a high Nd/Zn ratio), texture weakening is maintained even after complete recrystallization and grain coarsening, while in the Mg-4Zn-1Nd alloy, texture strengthening occurs after grain coarsening, and a single peak replaces the double split basal peaks. In the Mg-1Zn-1Nd alloy, grain coarsening is accompanied by a bimodal grain size distribution, whereas in the Mg-4Zn-1Nd alloy, the grain coarsening leads to a uniform grain size distribution. TEM investigations show the formation of the Zn and Nd rich clusters at early stage of annealing in both alloys. During recrystallization, these clusters were dissolved in the Mg-4Zn-1Nd alloy, but they are more stable in the Mg-1Zn-1Nd alloy. In our opinion, the formation of these stable clusters is one of the main factors for texture weakening of the Mg-Zn-RE alloys.

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Understanding the effect of grain size distribution on the stability of nanocrystalline materials: An analytical approach

Materialia ◽

10.1016/j.mtla.2019.100579 ◽

2020 ◽

Vol 9 ◽

pp. 100579 ◽

Cited By ~ 1

Author(s):

Srikant Gollapudi ◽

Ajay K Soni

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Nanocrystalline Materials ◽

Analytical Approach ◽

The Stability

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Statistical Analysis of Histograms of Grain Size Distribution in Nanostructured Materials Processed by Severe Plastic Deformation

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.284.431 ◽

2018 ◽

Vol 284 ◽

pp. 431-435 ◽

Cited By ~ 4

Author(s):

Alexey V. Stolbovsky ◽

Elena Farafontova

Keyword(s):

Plastic Deformation ◽

Grain Size ◽

Statistical Analysis ◽

Severe Plastic Deformation ◽

Size Distribution ◽

Nanostructured Materials ◽

Grain Size Distribution ◽

Grain Structure ◽

Standard Distribution ◽

Statistical Analysis Methods

Analysis of histograms of grain size distribution of materials nanostructured by severe plastic deformation has been carried out using statistical analysis methods. It has been established that in materials with quite homogeneous nanostructure, the fitting of histograms of grain size distribution by using a logarithmic standard distribution is not accurate enough. It is proposed to compensate for the observed imprecision by including into the model the additional component – normal distribution. It is shown that this approach is applicable to nanostructured materials with both the deformation-origin nanostructure and the grain structure formed during annealing.

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Control of Microstructure by Laser Spot Heating

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.127.337 ◽

2007 ◽

Vol 127 ◽

pp. 337-342 ◽

Cited By ~ 2

Author(s):

Toshiya Shibayanagi ◽

Masahiro Tsukamoto ◽

N. Matsuda ◽

Y. Soga ◽

Nobuyuki Abe ◽

...

Keyword(s):

Computer Simulation ◽

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Laser System ◽

Grain Structure ◽

Laser Spot ◽

Heating Process ◽

Polycrystalline Aluminum ◽

Different Grain Size

The present study tried to control grain structure in polycrystalline aluminum or titanium by means of a laser spot heating method as well as by a computer simulation technique. Monte Carlo simulation of spot heating was performed utilizing two-dimensional grain structure model composed of 200 x 200 sites with hexagonal cells. Grain growth proceeded preferentially in the higher temperature region and resulted in a large grain surrounded by small grains. This large grain tended to keep on growing during homogeneous heating after the spot heating, suggesting that the spot heating technique can fabricate a peculiar grain structure such as different grain size distribution and texture that are not realized by utilizing conventional uniform heating process. Laser spot heating utilizing a fiber-laser system realized heating of small area such as 30micorn diameter to bring about peculiar grain size distribution as calculated by the computer simulation.

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Grain Growth, Stress, and Impurities in Electroplated Copper

Journal of Materials Research ◽

10.1557/jmr.2002.0082 ◽

2002 ◽

Vol 17 (3) ◽

pp. 582-589 ◽

Cited By ~ 90

Author(s):

S. H. Brongersma ◽

E. Kerr ◽

I. Vervoort ◽

A. Saerens ◽

K. Maex

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Growth ◽

Sheet Resistance ◽

Grain Size Distribution ◽

High Temperatures ◽

Intermediate State ◽

Growth Stress ◽

Grain Structure ◽

Electroplated Copper

The widely observed secondary grain growth in electroplated Copper layers is shown to be incomplete after the sheet resistance and stress of the layer appear to have stabilized. Instead the layer is in an intermediate state with a grain size distribution that depends on the plating conditions. Further extensive annealing at high temperatures results in an additional considerable enlargement of the grain structure, accompanied by an additional decrease of the sheet resistance and desorption of impurities that were incorporated during plating.

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