Change of misorientation of individual grains in fatigue of polycrystalline alloys by diffraction contrast tomography using ultrabright synchrotron radiation

Nakai, Yoshikazu; Shiozawa, Daiki; Asakawa, Naoya; Nonaka, Kenji; Kikuchi, Shoichi

doi:10.1016/j.prostr.2017.04.058

Cited by 10 publications

(11 citation statements)

References 14 publications

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“…Moreover, some of the issues of mineral differentiation with µCT can be alleviated by the use of other contrast modes such as diffraction-contrast tomography (DCT) and phase-contrast tomography (PCT), which is mainly available only in synchrotron sources. Both contrast modes have found applications mostly in analysis of microstructures in crystalline samples, as it allows the high contrast between phases [48][49][50][51][52][53]. Synchrotron systems also open up possibilities of complimentary tomography methods such as X-ray diffraction microtomography (XRD-CT) and X-ray Fluorescence microtomography (XRF-CT).…”

Section: Measurementsmentioning

confidence: 99%

X-ray Microcomputed Tomography (µCT) for Mineral Characterization: A Review of Data Analysis Methods

et al. 2019

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The main advantage of X-ray microcomputed tomography (µCT) as a non-destructive imaging tool lies in its ability to analyze the three-dimensional (3D) interior of a sample, therefore eliminating the stereological error exhibited in conventional two-dimensional (2D) image analysis. Coupled with the correct data analysis methods, µCT allows extraction of textural and mineralogical information from ore samples. This study provides a comprehensive overview on the available and potentially useful data analysis methods for processing 3D datasets acquired with laboratory µCT systems. Our study indicates that there is a rapid development of new techniques and algorithms capable of processing µCT datasets, but application of such techniques is often sample-specific. Several methods that have been successfully implemented for other similar materials (soils, aggregates, rocks) were also found to have the potential to be applied in mineral characterization. The main challenge in establishing a µCT system as a mineral characterization tool lies in the computational expenses of processing the large 3D dataset. Additionally, since most of the µCT dataset is based on the attenuation of the minerals, the presence of minerals with similar attenuations limits the capability of µCT in mineral segmentation. Further development on the data processing workflow is needed to accelerate the breakthrough of µCT as an analytical tool in mineral characterization.

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Section: Measurementsmentioning

confidence: 99%

X-ray Microcomputed Tomography (µCT) for Mineral Characterization: A Review of Data Analysis Methods

et al. 2019

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“…By SR‐μCT imaging, we successfully observed the shape and propagation behavior of fatigue cracks 38,50–52 . Microstructural alterations related to fatigue crack initiation were also observed by diffraction contrast tomography (DCT) using ultrabright synchrotron radiation X‐rays 53,54 . SR‐μCT has been applied to the observation of the RCF process; however, the penetration depth of ultrabright synchrotron radiation X‐rays is limited, so the sample size should be less than 1 mm in all directions.…”

Section: Introductionmentioning

confidence: 99%

“…38,[50][51][52] Microstructural alterations related to fatigue crack initiation were also observed by diffraction contrast tomography (DCT) using ultrabright synchrotron radiation X-rays. 53,54 SR-μCT has been applied to the observation of the RCF process; however, the penetration depth of ultrabright synchrotron radiation X-rays is limited, so the sample size should be less than 1 mm in all directions. Then samples should be cut from a bulk specimen to include damaged areas.…”

Section: Introductionmentioning

confidence: 99%

Inclusion orientation dependent flaking process in rolling contact fatigue observed by laminography using ultrabright synchrotron radiation X‐ray

Nakai

Shiozawa

Kikuchi

et al. 2022

Fatigue Fract Eng Mat Struct

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The formation and propagation of cracks in rolling contact fatigue were observed by synchrotron radiation computed laminography, and the effect of stringer-type inclusion orientation was examined. For longitudinal inclusions, cracks started forming at their tips. After cracks propagated toward the rolling direction, a longitudinal crack was kinked simultaneously at both its tips, and propagated toward the direction perpendicular to the rolling direction to form lateral cracks. After kinking, horizontal cracks were formed from the deepest point of a lateral crack, leading to flaking. On the other hand, for specimens with lateral inclusions, cracks propagated to the lateral direction without the formation of longitudinal cracks. Since the propagation life of lateral cracks and that of horizontal cracks were unrelated to the inclusion orientation, the rolling contact fatigue life of specimens with longitudinal inclusions was considerably longer than that of specimens with lateral inclusions.

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“…Consequently, the harmonic-structured SUS304L exhibits a lower resistance to fatigue crack growth owing to grain refinement, and the formation of pores is suppressed by MM. In the future, the three-dimensional fatigue crack shape [41][42][43][44][45][46] and the misorientations near the crack initiation site [47][48][49] will be measured for SUS304L with fatigue damage using synchrotron radiation to describe the mechanism of fatigue crack initiation and propagation in greater detail.…”

Section: -7mentioning

confidence: 99%

Evaluation of Fatigue Properties under Four-point Bending and Fatigue Crack Propagation in Austenitic Stainless Steel with a Bimodal Harmonic Structure

Kikuchi

Nakatsuka

Nakai

et al. 2019

Frattura Ed Integrità Strutturale

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Austenitic stainless steel (JIS-SUS304L) with a bimodal harmonic structure, which is defined as a coarse-grained structure surrounded by a network of fine grains, was fabricated using powder metallurgy to improve both the strength and ductility. Four-point bending fatigue tests and Kdecreasing tests were conducted in air at room temperature under a stress ratio R of 0.1 to investigate fatigue crack propagation in SUS304L. The fatigue limit of this harmonic-structured material is higher than that of the material with a homogeneous coarse-grained structure. This is attributable to the formation of fine grains by mechanical milling and to the suppression of pore formation. In contrast, the threshold stress intensity range, Kth, for the harmonicstructured material is lower than that for the homogeneous coarse-grained material, while the crack growth rates, da/dN, are higher at comparable K. These results can be attributed to a reduction in the effective threshold stress intensity range, K eff,th , due to the presence of fine grains in the harmonic structure.

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Change of misorientation of individual grains in fatigue of polycrystalline alloys by diffraction contrast tomography using ultrabright synchrotron radiation

Cited by 10 publications

References 14 publications

X-ray Microcomputed Tomography (µCT) for Mineral Characterization: A Review of Data Analysis Methods

X-ray Microcomputed Tomography (µCT) for Mineral Characterization: A Review of Data Analysis Methods

Inclusion orientation dependent flaking process in rolling contact fatigue observed by laminography using ultrabright synchrotron radiation X‐ray

Evaluation of Fatigue Properties under Four-point Bending and Fatigue Crack Propagation in Austenitic Stainless Steel with a Bimodal Harmonic Structure

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