Processing Path Model to Describe Texture Evolution during Mechanical Processing

2005 ◽  
Vol 495-497 ◽  
pp. 977-982 ◽  
Author(s):  
Dong Sheng Li ◽  
J. Bouhattate ◽  
Hamid Garmestani
Keyword(s):  
Spherical Harmonics ◽  
Texture Evolution ◽  
Path Model ◽  
Polycrystalline Materials ◽  
Explicit Solutions ◽  
Mechanical Processing ◽  
Initial State ◽  
Texture Coefficients ◽  
Orientation Space ◽  
Spherical Harmonics Expansion

Using a processing path model based on the conservation principle in the orientation space explicit solutions can be formed linking any final (desired) microstructure to a given initial state for polycrystalline materials. The model uses texture coefficients in spherical harmonics expansion to as materials descriptors to represent the texture state of polycrystalline materials. In this work, the effect of increasing the maximum number of texture coefficients used in the series expansion (represented by Lmax) on the prediction of texture and its accuracy is fully studied.

Modelling of Microstructure and Texture and the Resulting Properties during the Thermo-Mechanical Processing of Aluminium Sheets

2006 ◽  
Vol 519-521 ◽  
pp. 1563-1568 ◽  
Author(s):  
Olaf Engler
Keyword(s):  
Texture Evolution ◽  
Mechanical Processing ◽  
Process Chain ◽  
Production Lines ◽  
Thermomechanical Process ◽  
Polycrystal Plasticity ◽  
History Of ◽  
Strain Paths ◽  
Aluminium Sheets ◽  
Evolution Of Microstructure

In order to predict the mechanical properties of Al sheet products, the evolution of microstructure and crystallographic texture along the process chain must be tracked. During the thermo-mechanical processing in commercial production lines the material experiences a complex history of temperature, time and strain paths, which results in alternating cycles of deformation and recrystallization with the associated changes in texture and microstructure. In the present paper the texture evolution of AA 3104 can body stock is modelled. In particular, the earing behaviour at final gauge is linked to the decisive steps of deformation and recrystallization along the thermomechanical process chain. For this purpose, the textures predicted by a comprehensive throughprocess model of the texture evolution during the thermo-mechanical production of Al sheet are input into a polycrystal-plasticity approach to simulate earing of the final gauge sheets.

Simulating the diffraction line profile from nanocrystalline powders using a spherical harmonics expansion

2018 ◽  
Vol 74 (6) ◽  
pp. 640-646
Author(s):  
K. R. Beyerlein ◽  
P. Scardi
Keyword(s):  
Line Profile ◽  
Spherical Harmonics ◽  
Diffraction Line ◽  
Nanocrystalline Powders ◽  
Computationally Efficient ◽  
Profile Function ◽  
Diffraction Line Profile ◽  
Cubic Crystallites ◽  
Crystallite Shape ◽  
Spherical Harmonics Expansion

An accurate description of the diffraction line profile from nanocrystalline powders can be obtained by a spherical harmonics expansion of the profile function. The procedure outlined in this work is found to be computationally efficient and applicable to the line profile for any crystallite shape and size. Practical examples of the diffraction pattern peak profiles resulting from cubic crystallites between 1 and 100 nm in size are shown.

scholarly journals Effect of Supra-Transus Deformation Conditions on Recrystallization of Beta Ti Alloy

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1278
Author(s):  
Chao Voon Samuel Lim ◽  
Yang Liu ◽  
Chen Ding ◽  
Aijun Huang
Keyword(s):  
Hot Deformation ◽  
Static Recrystallization ◽  
Dynamic Recovery ◽  
Texture Evolution ◽  
High Strength ◽  
Ex Situ ◽  
Mechanical Processing ◽  
Ti Alloy ◽  
Electron Backscattered Diffraction ◽  
Beta Ti Alloy

There is increasing usage of high strength Beta Ti alloy in aerospace components. However, one of the major challenges is to obtain homogeneous refined microstructures via the thermo-mechanical processing. To overcome this issue, an understanding of the hot deformation conditions effect on the microstructure, prior to and after annealing, is needed. In this work, the effect of strain levels, which is more precise than percentage of reduction, and strain rate under supra-transus deformation temperature on beta annealing are studied using a double cone sample. The Electron Backscattered Diffraction (EBSD) is used to determine the deformed microstructure and texture evolution, as well as the static recrystallized grains evolution using the ex situ annealing approach. This work provides evidence that the mechanisms of dynamic recovery and recrystallization, along with texture evolution, are affected by the deformation conditions, which in turn affected the subsequent static recrystallization during annealing. It will also be shown that high levels of strain do not necessarily lead to an increase in the rate of recrystallization. Finally, the results obtained provided several examples of guidance in designing the TMP processes for obtaining not only a refine microstructure, but a more homogeneous beta microstructure during the beta processing of Beta Ti alloy.

scholarly journals Total Electron Content (TEC) estimation over Pakistan from local GPS network using spherical harmonics

2021 ◽  
Vol 64 (1) ◽  
Author(s):  
Maria Mehmood ◽  
Sajid Saleem ◽  
Renato Filjar ◽  
Najam Naqvi ◽  
Arslan Ahmed
Keyword(s):  
Spherical Harmonics ◽  
Orbit Determination ◽  
Region Of Interest ◽  
Local Model ◽  
Small Scale ◽  
Electron Content ◽  
Total Electron ◽  
Gps Network ◽  
Spherical Harmonics Expansion ◽  
The Impact

Many organizations allow GNSS users to access Global Ionosphere Maps (GIMS). However, the TEC estimates derived from GIMs are of insufficient quality to describe small-scale TEC variations over Pakistan. In this paper, the first local TEC map over Pakistan for the year 2019, derived from a regional GPS network, is presented. Spherical harmonics expansion is employed to estimate TEC with the spatial resolution of latitude 0.2° x longitude 0.2° and temporal resolution of 5 minutes. The impact of changing the degree/order of harmonics is assessed and it is determined that harmonic expansion up to 6 degrees is sufficient for estimating accurate TEC map for the region of interest. We have demonstrated that the TEC maps of Pakistan generated by local model conform better to the GIM by Center of Orbit Determination (CODE) (RMS = 5.83) as compared to International Reference Ionosphere (IRI-2016) (RMS = 7.18). We found that the TEC estimated by the local model shows a better correlation to measured TEC; CODE-GIM overestimated TEC, while IRI-2016 underestimates it. Moreover, it was observed that TEC peaks during noon (1100-0100 LT) and Equinox (April). The residuals of local TEC estimates with respect to TEC obtained from CODE- GIM indicate the inaccuracy of CODE-GIM over the region of Pakistan: highest deviation of TEC from local model with respect to CODE –GIM was observed in April (RMS = 8.73) and minimum in October (RMS = 2.78). We have also analyzed the performance of our maps in geomagnetically disturbed days. The research presented in this paper will contribute towards the ionosphere study over Pakistan, where limited research is available currently.

FISSION DYNAMICS IN THE FOUR-DIMENSIONAL DEFORMATION SPACE

2006 ◽  
Vol 15 (02) ◽  
pp. 417-425 ◽  
Author(s):  
KRZYSZTOF POMORSKI ◽  
JOHANN BARTEL
Keyword(s):  
Spherical Harmonics ◽  
Deformation Space ◽  
Neck Formation ◽  
Deformation Parameters ◽  
Fission Barriers ◽  
Spherical Harmonics Expansion ◽  
Left Right Asymmetry ◽  
Rotating Nuclei

A four-dimensional deformation space adapted to describe the fission dynamics of hot, rotating nuclei is proposed. The deformation coordinates consisting of the elongation, neck formation, left-right asymmetry and nonaxiality result in fission barriers much lower and thiner than those obtained in the spherical-harmonics expansion using the same number of deformation parameters.

Boundary conditions for spherical harmonics expansion of Boltzmann equation

1992 ◽  
Vol 28 (11) ◽  
pp. 995-996 ◽  
Author(s):  
D. Schroeder ◽  
D. Ventura ◽  
A. Gnudi ◽  
G. Baccarani
Keyword(s):  
Boltzmann Equation ◽  
Boundary Conditions ◽  
Spherical Harmonics ◽  
Spherical Harmonics Expansion
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