Denoising of crystal orientation maps

Hielscher, Ralf; Silbermann, Christian B.; Schmidl, E.; Ihlemann, Joern

doi:10.1107/s1600576719009075

Cited by 102 publications

(45 citation statements)

References 29 publications

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“…As discussed in the introduction, various orientation filtering approaches have been used to improve the orientation precision of the raw orientation data derived from Hough‐based data analysis procedures (Humphreys, 2001; Chen & Kuo, 2010; Hielscher et al ., 2019; Seret et al ., 2019). It is thus pertinent to analyse the efficacy of the postprocessing orientation filters in comparison to the FPM approach.…”

Section: Discussionmentioning

confidence: 99%

“…In Figure 8, we show the result of this approach for the ‘infimal convolution’ filter introduced in Hielscher et al . (2019) and as implemented in MTEX 5.2. When we choose the filter parameters

α = β = 10^{- 4}

, the dislocation features of the FPM result in Figure 8(A) are already significantly smoothed in (b), but still visible.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, we have also verified that stronger filtering leads to an increased smoothing of orientation features in the grain. To visualise the resulting loss of spatial resolution, in Figure 9 we show the filtering results assuming

α = β = 0.0075

(this choice is based on Hielscher et al ., 2019, fig. 11) for both the RA data and the FPM refinement results.…”

Section: Discussionmentioning

confidence: 99%

“…Determination of parameters for the infimal convolution filter (Hielscher et al ., 2019) based on their effect on high‐precision orientation data. Compared to the best fit pattern matching result in (A), (the high‐precision ‘ground truth’), the parameters α , β = 10 −4 lead to a moderate smoothing without complete loss of the dislocation features in (B).…”

Section: Discussionmentioning

confidence: 99%

“…There has therefore been an increase in the development of other methods to improve on or complement the information available from EBSD measurements and to derive more information from them, as fast EBSD detectors increase the ease with which they can be captured. One approach is to postprocess the orientation information delivered by the EBSD system, using for example Kuwahara filters (Humphreys, 2001; Humphreys et al ., 2001), bilateral filters (Chen & Kuo, 2010), spline‐based filters (Seret et al ., 2019), variational methods from mathematical image analysis (Hielscher et al ., 2019) or pattern averaging (Wright et al ., 2015). These filtering approaches can involve a loss of spatial information if operated on features with dimensions approaching the filter kernel size.…”

Section: Introductionmentioning

confidence: 99%

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Improving EBSD precision by orientation refinement with full pattern matching

Winkelmann

Jablon

Tong

et al. 2020

Journal of Microscopy

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Summary We present a comparison of the precision of different approaches for orientation imaging using electron backscatter diffraction (EBSD) in the scanning electron microscope. We have used EBSD to image the internal structure of WC grains, which contain features due to dislocations and subgrains. We compare the conventional, Hough‐transform based orientation results from the EBSD system software with results of a high‐precision orientation refinement using simulated pattern matching at the full available detector resolution of 640 × 480 pixels. Electron channelling contrast imaging (ECCI) is used to verify the correspondence of qualitative ECCI features with the quantitative orientation data from pattern matching. For the investigated sample, this leads to an estimated pattern matching sensitivity of about 0.5 mrad (0.03°) and a spatial feature resolution of about 100 nm. In order to investigate the alternative approach of postprocessing noisy orientation data, we analyse the effects of two different types of orientation filters. Using reference features in the high‐precision pattern matching results for comparison, we find that denoising of orientation data can reduce the spatial resolution, and can lead to the creation of orientation artefacts for crystallographic features near the spatial and orientational resolution limits of EBSD.

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Section: Discussionmentioning

confidence: 99%

α = β = 10^{- 4}

, the dislocation features of the FPM result in Figure 8(A) are already significantly smoothed in (b), but still visible.…”

Section: Discussionmentioning

confidence: 99%

α = β = 0.0075

(this choice is based on Hielscher et al ., 2019, fig. 11) for both the RA data and the FPM refinement results.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improving EBSD precision by orientation refinement with full pattern matching

Winkelmann

Jablon

Tong

et al. 2020

Journal of Microscopy

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Effect of Grain Statistics on Micromechanical Modeling: The Example of Additively Manufactured Materials Examined by Electron Backscatter Diffraction

et al. 2020

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Micromechanical modeling is one of the prominent numerical tools for the prediction of mechanical properties and the understanding of deformation mechanisms of metals. As input parameters, it uses data obtained from microstructure characterization techniques, among which the electron backscatter diffraction (EBSD) technique allows us to understand the nature of microstructural features, that are usually described by statistics. Because of these advantages, the EBSD dataset is widely used for synthetic microstructure generation. However, for the statistical description of microstructural features, the population of input data must be considered. Preferably, the EBSD measurement area must be sufficiently large to cover an adequate number of grains. However, a comprehensive study of this measurement area with a crystal plasticity finite element method (CPFEM) framework is still missing although it would considerably facilitate information exchange between experimentalists and simulation experts. Herein, the influence of the EBSD measurement area and the number of grains on the statistical description of the microstructural features and studying the corresponding micromechanical simulation results for 316L stainless steel samples produced by selective laser melting is investigated.

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Evolution of local misorientations in the γ/γ’‐microstructure of single crystal superalloys during creep studied with the rotation vector baseline (RVB) EBSD method

Gamanov,

Dlouhy,

Bürger

et al. 2023

Microscopy Res & Technique

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The present work uses the rotation vector baseline electron back scatter orientation imaging method (RVB‐EBSD) to study the evolution of small misorientations between the γ‐ and γ′‐phase in Ni‐base single crystal superalloys (SXs) during creep. For this purpose, two material states of the SX ERBO1 (CMSX4 type) were characterized after creep deformation at 850°C and 600 MPa to final strains of 1% and 2%. Obtaining reliable phase boundary misorientation (PBM), kernel average misorientation (KAM) and orientation spread (OS) data represents a challenge for electron backscatter diffraction (EBSD), not only because the method operates at its limits of lateral and angular resolution, but also because it is difficult to differentiate between the two phases merely based on Kikuchi diffraction. The two phases differ in chemical composition which gives rise to different EBSD background intensities. These can be exploited to differentiate between the two phases. In the present work, crystallographic and chemical information are combined to demonstrate that orientation imaging can be used to document the formation of dislocation networks at γ/γ′‐interfaces and the filling of γ‐channels by dislocations. These findings are in good agreement with reference results from diffraction contrast scanning transmission electron microscopy. It is also shown that misorientations evolve between small groups of equally oriented γ/γ′‐neighborhoods, on a size scale above characteristic γ/γ′‐dimensions (>0.5 μm) and below distances associated with dendritic mosaicity (<200 μm). The methodological aspects as well as the new material specific results are discussed in the light of previous work published in the literature.Research Highlights Microstructure evolution during [001] tensile creep of Ni‐based single‐crystalline alloy. Application of RVB‐EBSD technique, focused on angular misorientations between γ/γ′ phases, with accuracy of 0.01°. Separation of γ/γ′ phases using experimental post‐processing of raw EBSD data.

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Denoising of crystal orientation maps

Cited by 102 publications

References 29 publications

Improving EBSD precision by orientation refinement with full pattern matching

Improving EBSD precision by orientation refinement with full pattern matching

Effect of Grain Statistics on Micromechanical Modeling: The Example of Additively Manufactured Materials Examined by Electron Backscatter Diffraction

Evolution of local misorientations in the γ/γ’‐microstructure of single crystal superalloys during creep studied with the rotation vector baseline (RVB) EBSD method

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