scholarly journals Influence of Residual Stress Around Constituent Particles on Recrystallization and Grain Growth in Al-Mn-Based Alloy during Annealing

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1701
Author(s):  
Sung-Jin Park ◽  
Shinji Muraishi
Keyword(s):  
Residual Stress ◽  
Dislocation Density ◽  
Grain Boundaries ◽  
Nucleation And Growth ◽  
X Ray ◽  
Total Displacement ◽  
Initial Dislocation Density ◽  
Cold Rolled ◽  
Inhomogeneity Problem ◽  
Misorientation Angles

Effect of the residual stress on the recovery and recrystallization behaviors of the cold-rolled AA3003 aluminum alloy was investigated. The evolution of deformed microstructure and dislocation density characterized by TEM and Synchrotron X-ray measurements found that the change in the ratio between low angle grain boundaries (LAGBs) and high angle grain boundaries (HAGBs) during annealing is varied depending on the initial dislocation density, where the value of HAGB/LAGBs ratio is amounted to be about 0.8 at maximum. The nucleation and growth rate of the recrystallized grains are strongly dependent on the net driving pressure associated with dislocation density increased by the amount of reduction. EBSD analysis revealed that the deformed zone composed of the fine equi-axed grains with large misorientation angles would be formed in the vicinity of the constituent particles, which is consistent with the region of the large residual stress and total displacement predicted by Eshelby inhomogeneity problem under cold rolling condition.

Recrystallization Investigated by X- Ray Diffraction Imaging

2007 ◽  
Vol 550 ◽  
pp. 631-636 ◽  
Author(s):  
Thomas Wroblewski ◽  
Adeline Buffet
Keyword(s):  
Nucleation And Growth ◽  
Single Shot ◽  
X Ray Diffraction ◽  
Growth Behaviour ◽  
Large Area ◽  
Polycrystalline Specimen ◽  
X Ray ◽  
Classical Models ◽  
Diffraction Imaging ◽  
Cold Rolled

X-ray diffraction imaging allows the investigation of a large area of a polycrystalline specimen in a single shot. Dynamic processes like recystallization can, therefore, be studied without prior knowledge of where they occur. Even early stages of nucleation can be traced back using the information from images taken from the fully recrystallized specimen. Experiments performed at HASYLAB beamline G3 on cold rolled Cu and Al showed nucleation and growth behaviour that cannot be explained by classical models.

Influence of Plastic Pre-Strain on Low-Temperature Gas Carburization of 316L Austenitic Stainless Steel

2016 ◽  
Vol 853 ◽  
pp. 178-183 ◽  
Author(s):  
Ya Wei Peng ◽  
Jian Ming Gong ◽  
Yong Jiang ◽  
Ming Hui Fu ◽  
Dong Song Rong
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Low Temperature ◽  
Dislocation Density ◽  
Carbon Diffusion ◽  
Uniaxial Tensile ◽  
Engineering Strain ◽  
X Ray ◽  
316L Austenitic Stainless Steel

In this paper, the influence of pre-strain on low-temperature gas carburization of 316L austenitic stainless steel was investigated. A group of flat specimens were uniaxial tensile to several levels of pre-strain including 5%, 10%, 15%, 20% and 25% engineering strain. Then, the pre-strained specimens was treated by low-temperature gas carburization at 470 °C for 30 h. In order to elucidate the effect of pre-strain on low-temperature gas carburization, optical microscopy (OM), X-ray diffractometer (XRD), scanning electron probe micro-analyzer (EPMA), microhardness tester and residual stress analyzer were used. Meanwhile, dislocation density of the pre-strained specimens was semi-quantitatively measured by means of X-ray diffraction analysis and the role of dislocation density on carbon diffusion during low-temperature gas carburization was discussed. The results show as follow: (1) the thicknesses of the carburized layers are independent of the pre-strain degree. (2) dislocation density increases with the increasing pre-strain, but almost has no effect on carbon diffusion at the given carburizing temperature. (3) an outstanding surface with hardness (≈ 1150 HV0.1) and compressive residual stress (≈1900 MPa) is introduced by low-temperature gas carburization, and the strengthening results of carburization are unaffected by pre-strain.

High Resolution X-ray Diffraction Analysis of GaN-Based Heterostructures Grown by OMVPE

1996 ◽  
Vol 449 ◽  
Author(s):  
M.S. Goorsky ◽  
A.Y. Polyakov ◽  
M. Skowronski ◽  
M. Shin ◽  
D.W. Greve
Keyword(s):  
High Resolution ◽  
Dislocation Density ◽  
Layer Thickness ◽  
Vapor Phase ◽  
Edge Dislocation ◽  
Initial Level ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Perfection ◽  
Misorientation Angles

ABSTRACTWe demonstrate the use of triple axis diffraction measurements, including Φ scans (in which the sample is rotated about an axis perpendicular to its surface) to assess the crystal perfection of wurtzite GaN layers on sapphire grown using different pre-nitridation growth treatments by or-ganometallic vapor phase epitaxy. The Φ scans determine the in-plane misorientation angles between the crystallites and hence provide information on the edge dislocation density. Using glancing incidence (1014) and (1015) reflections, we determined that the misorientation among the GaN crystallites decreases with increasing layer thickness and that the pre-nitridation conditions control the initial level of misorientation. Triple axis ω and ω-2θ scans around the (0002) reflection did not show a systematic trend with increasing layer thickness. However, layers grown without a pre-nitridation step tended to exhibit higher values of both mosaic spread and strain. The appropriate asymmetric reflections for GaN-based Φ scan measurements are determined using structure factor calculations, which are presented here.

Evaluation of intragranular strain and average dislocation density in single grains of a polycrystal using K-map scanning

2016 ◽  
Vol 49 (5) ◽  
pp. 1814-1817 ◽  
Author(s):  
Ernesto Filippelli ◽  
Gilbert Chahine ◽  
András Borbély
Keyword(s):  
Residual Stress ◽  
Dislocation Density ◽  
Three Dimensional ◽  
Tensile Load ◽  
Polycrystalline Materials ◽  
Strain Component ◽  
Reciprocal Space Mapping ◽  
X Ray ◽  
Average Dislocation Density ◽  
Single Grain

Quick scanning X-ray microscopy combined with three-dimensional reciprocal space mapping was applied to characterize intragranular orientation and strain in a single grain of uniaxially deformed Al polycrystal. The strain component perpendicular to the direction of the applied tensile load was found to be very heterogeneous with high compressive and tensile values in the grain interior and near two grain boundaries, respectively. The distribution of the magnitude of diffraction vectors indicates that dislocations are the origin of the strain. The work opens new possibilities for analysing dislocation structures and intragranular residual stress/strain in single grains of polycrystalline materials.

scholarly journals Effects of Pulsed Magnetic Fields of Different Intensities on Dislocation Density, Residual Stress, and Hardness of Cr4Mo4V Steel

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 115 ◽  
Author(s):  
Mingdong Hou ◽  
Kejian Li ◽  
Xiaogang Li ◽  
Xu Zhang ◽  
Shaoshi Rui ◽  
...  
Keyword(s):  
Residual Stress ◽  
Magnetic Fields ◽  
Dislocation Density ◽  
Compressive Residual Stress ◽  
Electron Backscatter Diffraction ◽  
Dislocation Motion ◽  
Pulsed Magnetic Fields ◽  
X Ray ◽  
Average Value ◽  
Backscatter Diffraction

To study the effects of pulsed magnetic fields of different intensities on the dislocation density, residual stress, and hardness of Cr4Mo4V steel, magnetic treatment is conducted at 0, 1.0, 1.3, 1.5, 2.0, and 2.5 T. The dislocation density and residual stress are measured using Electron Backscatter Diffraction (EBSD) and X-ray technique, respectively. The results reveal the dislocation density and compressive residual stress decrease at lower magnetic fields such as 1.0 T and 1.3 T, while they increase at higher magnetic fields such as 2.0 T and 2.5 T. The average value of kernel averaged misorientation (KAM) and compressive residual stress decrease about 10.4% and 15.8%, respectively, at 1.0 T, while they increase about 5.88% and 18.2%, respectively, at 2.5 T. The average value of hardness decreases about 3.5% at 1.0 T, from 817 HV to 787 HV. With the increments of intensities, the hardness of the treated samples increases. The hardness essentially remains unchanged at 2.0 T and 2.5 T. The reason for the dislocation motion under the action of pulsed magnetic fields is discussed.

Measurement of Dislocation Density in Cold-Drawn Steel Wires by Means of X-Ray Bragg Profiles Analysis

2012 ◽  
Vol 184-185 ◽  
pp. 1054-1059
Author(s):  
Fan Yang ◽  
Ying Ying Fan ◽  
Yi Ming Jin
Keyword(s):  
Dislocation Density ◽  
True Strain ◽  
Pearlitic Steel ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Line Profile ◽  
Steel Wires ◽  
Initial Dislocation Density ◽  
Cold Worked

Cold-drawn pearlitic steel wires are widely used in numerous engineering fields. One of the most powerful analysis methods on determining the dislocation character of this heavily cold worked material is to investigate the X–ray diffraction line-profile broadening. Fourier line–broadening analysis in steel wires with near eutectoid composition indicates that with cumulative true strains, the initial dislocation density of 6×1014m-2in the rods increases at least one magnitude in wires. Up to 1.5×1016m-2of dislocation density is found in the ferrite lamella of wires with a true strain of 2.77.

Effect of Nanocrystalline Structure and Polygonized Dislocation Substructure on Ti-Ni Martensite Lattice Parameters and Transformation Lattice Strain

2008 ◽  
Vol 584-586 ◽  
pp. 475-480 ◽  
Author(s):  
Sergey Prokoshkin ◽  
Andrey Korotitskiy ◽  
Vladimir Brailovski ◽  
K.E. Inaekyan
Keyword(s):  
Dislocation Density ◽  
Dislocation Substructure ◽  
Subgrain Size ◽  
Nanocrystalline Structure ◽  
Transformation Strain ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ni Alloys ◽  
Cold Rolled

The Ti-50.26 and 50.61at.%Ni alloys were cold-rolled with true strains from e=0.3 to 2.1. Post-deformation annealing in the 200 to 500°C temperature range after a moderate deformation (e=0.3) produced a polygonized dislocation substructure with various dislocation density and subgrain size, while after severe plastic deformation (e=1.7-1.9), a nanocrystalline structure with various grain size was formed in the B2-austenite. An X-ray diffraction study shows that lattice parameters of B19'-martensite formed from (a) partially recovered and polygonized or (b) nanocrystalline austenites differ from the corresponding parameters of the martensite formed from quenched (recrystallized) austenite. This difference increases with nanocrystalline grain refinement and with an increase in residual dislocation density and subgrain refinement. The maximum martensitic transformation strain has the highest value for the martensite formed in recrystallized austenite, and this value decreases with nanograin refinement and with an increase in dislocation density and subgrain refinement.

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