scholarly journals Initiation and short crack growth behaviour of environmentally induced cracks in AA5083 H131 investigated across time and length scales

2019 ◽  
Vol 37 (5) ◽  
pp. 469-481 ◽  
Author(s):  
Visweswara C. Gudla ◽  
Alistair Garner ◽  
Malte Storm ◽  
Parmesh Gajjar ◽  
James Carr ◽  
...  
Keyword(s):  
Electron Backscatter Diffraction ◽  
Three Dimensional ◽  
High Strength ◽  
Time Lapse ◽  
Growth Behaviour ◽  
Spectroscopy Analysis ◽  
Crack Growth Behaviour ◽  
Rate Testing ◽  
X Ray Computed ◽  
Backscatter Diffraction

AbstractEnvironmentally induced cracking (EIC) in a sensitized high-strength AA5083 H131 alloy has been investigated using time-lapse synchrotron X-ray computed tomography combined with post-mortem correlative characterization. Small corrosion features deliberately introduced in a pre-exposure step were found to be the site of initiation for over 95% of the 44 EIC cracks that developed under slow strain rate testing. Detailed analysis using three-dimensional electron backscatter diffraction and energy-dispersive spectroscopy analysis of a single crack confirmed the intergranular nature of the cracks from the start and that the pre-exposure corrosion was associated with an α-AlFeMnSi particle cluster. It also appears that several cracks may have initiated at this site, which later coalesced to form the 300-μm-long crack that ultimately developed. Of further note is the fact that initiation of the EIC cracks across the sample started below the yield strength and continued beyond the ultimate tensile strength. The most rapid crack propagation occurred during sample extension following a period of fixed displacement.

scholarly journals Validation of three-dimensional diffraction contrast tomography reconstructions by means of electron backscatter diffraction characterization

2013 ◽  
Vol 46 (4) ◽  
pp. 1145-1150 ◽  
Author(s):  
Melanie Syha ◽  
Andreas Trenkle ◽  
Barbara Lödermann ◽  
Andreas Graff ◽  
Wolfgang Ludwig ◽  
...  
Keyword(s):  
Electron Backscatter Diffraction ◽  
Three Dimensional ◽  
Data Reconstruction ◽  
Characterization Methods ◽  
Diffraction Contrast ◽  
Ebsd Data ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Tomography Data ◽  
Good Agreement

Microstructure reconstructions resulting from diffraction contrast tomography data of polycrystalline bulk strontium titanate were reinvestigated by means of electron backscatter diffraction (EBSD) characterization. Corresponding two-dimensional grain maps from the two characterization methods were aligned and compared, focusing on the spatial resolution at the internal interfaces. The compared grain boundary networks show a remarkably good agreement both morphologically and in crystallographic orientation. Deviations are critically assessed and discussed in the context of diffraction data reconstruction and EBSD data collection techniques.

scholarly journals Visualization of the Bainite Fine Structure Using EBSD and Euler Angles

2019 ◽  
Vol 1 (1) ◽  
pp. 11
Author(s):  
Yu.V. Yudin ◽  
A.A. Kuklina ◽  
M.V. Maisuradze ◽  
M.S. Karabanalov
Keyword(s):  
Fine Structure ◽  
Electron Backscatter Diffraction ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Bainitic Steel ◽  
Near Surface ◽  
Steel Microstructure ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Ebsd Method

The electron backscatter diffraction method (EBSD) is widely used to studycrystallographic orientational relationships of the steel microstructure constituentsincluding bainite. Nevertheless the fine structure of bainite (subunits, plates) is notinvestigated by this method. In this paper we propose a technique for visualizing ofthe structure of a bainitic steel near-surface layer using the values of Euler anglesobtained by EBSD method. A three-dimensional picture of the bainite fine structure ofthe HY-TUF steel obtained by the proposed technique is in

Determining the orientation of parent β grain from one α variant in titanium alloys

2018 ◽  
Vol 51 (4) ◽  
pp. 1125-1132 ◽  
Author(s):  
Z. B. Zhao ◽  
Q. J. Wang ◽  
H. Wang ◽  
J. R. Liu ◽  
R. Yang
Keyword(s):  
Titanium Alloys ◽  
Habit Plane ◽  
Electron Backscatter Diffraction ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Plane Normal ◽  
Β Phase ◽  
Microstructural Morphology ◽  
Backscatter Diffraction ◽  
The Relationship

The relationship between the crystallographic orientation and habit plane normal of transformed α laths in titanium alloys is discussed according to the Burgers orientation relationship and the three-dimensional structure of the α lath. A new method (orientation–trace method) is developed to determine the orientation of the parent β phase using the orientation of the α lath, which was measured by electron backscatter diffraction, and the microstructural morphology of that α variant. This approach is validated in a near-α titanium alloy. Moreover, the habit plane normal direction of the transformed α lath can be obtained from the crystallographic orientations of the α lath itself and its parent β grain. The verification and the corresponding discussion show the reliability of this approach.

Determination of crystal phase from an electron backscatter diffraction pattern

2009 ◽  
Vol 42 (2) ◽  
pp. 234-241 ◽  
Author(s):  
David J. Dingley ◽  
Stuart I. Wright
Keyword(s):  
Crystal Orientation ◽  
Electron Backscatter Diffraction ◽  
Hexagonal Phase ◽  
Three Dimensional ◽  
Lattice Parameters ◽  
Crystal Phase ◽  
Test Case ◽  
Electron Backscatter ◽  
Ebsd Pattern ◽  
Backscatter Diffraction

Electron backscatter diffraction (EBSD) is a scanning electron microscope-based technique principally used for the determination and mapping of crystal orientation. This work describes an adaptation of the EBSD technique into a potential tool for crystal phase determination. The process can be distilled into three steps: (1) extracting a triclinic cell from a single EBSD pattern, (2) identifying the crystal symmetry from an examination of the triclinic cell, and (3) determining the lattice parameters. The triclinic cell is determined by finding the bands passing through two zone axes in the pattern including a band connecting the two. A three-dimensional triclinic unit cell is constructed based on the identified bands. The EBSD pattern is indexed in terms of the triclinic cell thus formed and the crystal orientation calculated. The pattern indexing results in independent multiple orientations due to the symmetry the crystal actually possesses. By examining the relationships between these multiple orientations, the crystal system is established. By comparing simulated Kikuchi bands with the pattern the lattice parameters can be determined. Details of the method are given for a test case of EBSD patterns obtained from the hexagonal phase of titanium.

X-ray diffraction contrast tomography: a novel technique for three-dimensional grain mapping of polycrystals. II. The combined case

2008 ◽  
Vol 41 (2) ◽  
pp. 310-318 ◽  
Author(s):  
Greg Johnson ◽  
Andrew King ◽  
Marcelo Goncalves Honnicke ◽  
J. Marrow ◽  
Wolfgang Ludwig
Keyword(s):  
Electron Backscatter Diffraction ◽  
Three Dimensional ◽  
Real Data ◽  
X Ray Diffraction ◽  
Data Set ◽  
Transmitted Beam ◽  
X Ray ◽  
Diffraction Contrast ◽  
Simultaneous Acquisition ◽  
Backscatter Diffraction

By simultaneous acquisition of the transmitted and the diffracted beams, the applicability of the previously introduced diffraction contrast tomography technique [Ludwig, Schmidt, Lauridsen & Poulsen (2008).J. Appl. Cryst.41, 302–309] can be extended to the case of undeformed polycrystalline samples containing more than 100 grains per cross section. The grains are still imaged using the occasionally occurring diffraction contribution to the X-ray attenuation coefficient, which can be observed as a reduction in the intensity of the transmitted beam when a grain fulfils the diffraction condition. Automating the segmentation of the extinction spot images is possible with the additional diffracted beam information, even in the presence of significant spot overlap. By pairing the corresponding direct (`extinction') and diffracted beam spots a robust sorting and indexing approach has been implemented. The analysis procedure is illustrated on a real data set and the result is validated by comparison with a two-dimensional grain map obtained by electron backscatter diffraction.

Hydrogen effects on fracture of high-strength steels with different micro-alloying

2015 ◽  
Vol 33 (6) ◽  
pp. 515-527 ◽  
Author(s):  
Olga Todoshchenko ◽  
Yuriy Yagodzinskyy ◽  
Valentina Yagodzinska ◽  
Tapio Saukkonen ◽  
Hannu Hänninen
Keyword(s):  
Chemical Composition ◽  
Electron Backscatter Diffraction ◽  
High Strength Steels ◽  
Thermal Desorption Spectroscopy ◽  
High Strength ◽  
Constant Load ◽  
Carbon Steels ◽  
Hydrogen Induced Cracking ◽  
Load Tests ◽  
Backscatter Diffraction

AbstractConstant load tests of high-strength carbon steels with different micro-alloying using strengths in the range of 1000–1400 MPa were performed at ambient temperature under continuous electrochemical hydrogen charging. Hydrogen markedly affects delayed fracture of all the studied steels. Fractography of the studied steels shows that fracture mechanism depends on the chemical composition of the studied steels and hydrogen-induced cracking exhibits intergranular or transgranular character occurring often in the form of hydrogen flakes. The size and chemical composition of non-metallic inclusions are analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Hydrogen-induced cracking initiates at TiN/TiC particles in steels with Ti alloying. Crack paths are studied with electron backscatter diffraction mapping to analyze crack initiation and growth. The thermal desorption spectroscopy method is used to analyze the distribution of hydrogen in the trapping sites. The mechanisms of hydrogen effects on fracture of high-strength steels are discussed.

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