scholarly journals On Sampling Discrete Orientations from XRD for Texture Representation in Aggregates with Varying Grain Size

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1021
Author(s):  
Aditya Vuppala ◽  
Alexander Krämer ◽  
Johannes Lohmar
Keyword(s):  
Grain Size ◽  
Texture Evolution ◽  
Plastic Anisotropy ◽  
Experimental Measurements ◽  
Electrical Steels ◽  
Texture Representation ◽  
Electrical And Magnetic Properties ◽  
Grain Size Distributions ◽  
Size And Morphology ◽  
Orientation Optimization

The amount of orientation difference of crystallites, i.e., the texture in a metallic polycrystal governs, plastic anisotropy, electrical and magnetic properties of the material. For simulating the microstructure and texture evolution during forming processes, representative volume elements (RVEs) often generated based on experimental measurements are commonly used. While the grain size and morphology of polycrystals are often determined via light-optical microscopy, their texture is conventionally analyzed through diffraction experiments. Data from these different experiments must be correlated such that a representative set of sampled orientations is assigned to the grains in the RVE. Here, the concept Texture Sampling through Orientation Optimization (TSOO) is introduced, where based on the intensity the required number of orientations is first assigned to the grains of the RVE directly. Then the Bunge–Euler angles of all orientations are optimized in turn with respect to the experimental measurements. As orientations are assigned to grains of variable size during optimization, the compatibility between inhomogeneity in the microstructure and texture is inherently addressed. This method was tested for different microstructures of non-oriented electrical steels and showed good accuracy for homogenous and inhomogeneous grain size distributions.

Recrystallisation, Grain Growth and Texture Evolution in Nonoriented Electrical Steels

2007 ◽  
Vol 558-559 ◽  
pp. 657-664 ◽  
Author(s):  
Jong Tae Park ◽  
Jae Kwan Kim ◽  
Jerzy A. Szpunar
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Grain Growth ◽  
Texture Evolution ◽  
Size Control ◽  
Goss Texture ◽  
Final Annealing ◽  
Electrical Steels ◽  
Grain Size Control ◽  
Specific Orientation

The magnetic properties of nonoriented electrical steels are influenced by grain size and texture of final products. The key technology in the commercial production of nonoriented electrical steels is to grow grains with {hk0}<001> texture up to the optimum size in the final annealing process. The problems related to grain size control have been extensively investigated, while texture control has received much less attention. Therefore, there is enough room to improve the magnetic properties through the control of texture. In this study, systematic investigations on the texture evolution during both recrystallization and grain growth have been made. The formation of recrystallization texture is explained by oriented nucleation. This is supported by the fact that the area fraction of nuclei or recrystallized grains with specific orientation to all new grains remains almost constant during the progress of recrystallization. Most nuclei have a high misorientation angle of 25∼55° with the surrounding deformed matrices. During the progress of grain growth, the Goss texture component continues to decrease because the Goss grains have a high percentage of low angle, low mobility grain boundaries. The grains of Goss orientation have a smaller grain size than those of random orientation.

A Study of Texture Evolution during Deformation and Annealing in Fe 3 wt.-% Si by Orientation Contrast Microscopy

2007 ◽  
Vol 550 ◽  
pp. 539-544 ◽  
Author(s):  
Pablo Rodriguez-Calvillo ◽  
Roumen H. Petrov ◽  
Yvan Houbaert ◽  
Leo Kestens
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Plane Strain ◽  
Lattice Structure ◽  
Texture Evolution ◽  
Constant Strain Rate ◽  
Plane Strain Compression ◽  
Compression Tests ◽  
Electrical Steels ◽  
Average Grain Size

Electrical steels, in particular Fe-Si alloys, are used as magnetic flux carrier in transformers and motors because of their excellent magnetic properties. They owe these magnetic properties in part to the presence of specific texture components such as the Goss ({110} <001>) or the cube components ({001} <010>), but also to the chemical composition which is optimum with 6.5 wt. % Si. This high silicon content provides a stable BCC lattice structure to the alloy over the entire solid state domain, but also renders the material more brittle. This embrittlement, which is induced by ordering phenomena, makes it impossible to produce the alloy in a conventional rolling process unless a specific thermomechanical route at high temperature is applied. In order to examine the working behaviour of high Si electrical steels, a series of room temperature plane strain compression tests was carried out on a Fe-3%Si alloy in hot band condition. The samples were compressed with a constant strain rate of 20 s-1 to a reduction of 10, 35 and 70% and subsequently annealed for different times at 800 and 900°C in an electrical furnace without protecting atmosphere. The hot rolled microstructure displayed an average grain size of 195 7m and the texture showed on the cube component ({001} <010>) of maximum 5x random levels. After plane strain compression the samples developed the conventional α (<110> // RD) / γ (<111> // ND) fibre texture by plastic shear which was also accommodated, in part, by mechanical twinning. With regard to the annealed material, it was observed that the recrystallisation started in grains with the higher stored energy and within the shear bands. After a reduction of 70% the samples that were annealed at 800°C for 4 hours displayed an average grain size of 27 7m and a relative maximum of 4x random on the cube component. Also other less intense components such as the rotated cube ({001} <110>) and the Goss ({110} <001>) were present in the annealing texture. The samples that were annealed at 900°C, after a reduction of 70%, were characterized by an average grain size of 36 7m and by the appearance of the {111} <121> γ fibre component with an intensity of 4.7.

Microstructural Development of Electrical Steels under Si and Al Diffusion

2006 ◽  
Vol 258-260 ◽  
pp. 39-45
Author(s):  
José Barros ◽  
Yvan Houbaert
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Grain Growth ◽  
Alpha Phase ◽  
Microstructural Development ◽  
Diffusion Annealing ◽  
Electrical Steels ◽  
Common Features ◽  
Columnar Grain ◽  
Size And Morphology

The effect of Si and Al diffusion from a coating in the microstructure of electrical steels have been investigated for three different processing routes. In general the final texture is not affected by the diffusion of Si or Al from the coating whereas the grain size and mor- phology can be affected if the silicon content of the substrate is low enough to allow phase transformation. The gamma to alpha phase transformation caused by the diffusion of Si and Al determines the grain size and morphology resulting in columnar grain growth. The evolu- tion of the microstructures during the diffusion annealing for the production of high Si steels shows some common features with the microstructure evolution during the grain growth in conventional low silicon (Si < 3 wt.%) electrical steels.

scholarly journals Effect of Strain-Induced Precipitation on the Recrystallization Kinetics in a Model Alloy

2021 ◽  
Author(s):  
Mo Ji ◽  
Martin Strangwood ◽  
Claire Davis
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Avrami Exponent ◽  
Model Alloy ◽  
Size Distributions ◽  
Recrystallization Kinetics ◽  
Grain Size Distributions ◽  
Recrystallized Grain Size ◽  
Nb Addition

AbstractThe effects of Nb addition on the recrystallization kinetics and the recrystallized grain size distribution after cold deformation were investigated by using Fe-30Ni and Fe-30Ni-0.044 wt pct Nb steel with comparable starting grain size distributions. The samples were deformed to 0.3 strain at room temperature followed by annealing at 950 °C to 850 °C for various times; the microstructural evolution and the grain size distribution of non- and fully recrystallized samples were characterized, along with the strain-induced precipitates (SIPs) and their size and volume fraction evolution. It was found that Nb addition has little effect on recrystallized grain size distribution, whereas Nb precipitation kinetics (SIP size and number density) affects the recrystallization Avrami exponent depending on the annealing temperature. Faster precipitation coarsening rates at high temperature (950 °C to 900 °C) led to slower recrystallization kinetics but no change on Avrami exponent, despite precipitation occurring before recrystallization. Whereas a slower precipitation coarsening rate at 850 °C gave fine-sized strain-induced precipitates that were effective in reducing the recrystallization Avrami exponent after 50 pct of recrystallization. Both solute drag and precipitation pinning effects have been added onto the JMAK model to account the effect of Nb content on recrystallization Avrami exponent for samples with large grain size distributions.

scholarly journals Mean Field Analysis of Orientation Selective Grain Growth Driven By Interface-Energy Anisotropy

1994 ◽  
Vol 343 ◽  
Author(s):  
J. A. Floro ◽  
C. V. Thompson
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Growth ◽  
Texture Evolution ◽  
Mean Field ◽  
Orientation Distribution ◽  
Interface Energy ◽  
Abnormal Grain Growth ◽  
Field Analysis ◽  
Energy Anisotropy

ABSTRACTAbnormal grain growth is characterized by the lack of a steady state grain size distribution. In extreme cases the size distribution becomes transiently bimodal, with a few grains growing much larger than the average size. This is known as secondary grain growth. In polycrystalline thin films, the surface energy γs and film/substrate interfacial energy γi vary with grain orientation, providing an orientation-selective driving force that can lead to abnormal grain growth. We employ a mean field analysis that incorporates the effect of interface energy anisotropy to predict the evolution of the grain size/orientation distribution. While abnormal grain growth and texture evolution always result when interface energy anisotropy is present, whether secondary grain growth occurs will depend sensitively on the details of the orientation dependence of γi.

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