High-resolution Observation of Steel Using X-ray Tomography Technique

Abstract

A common, serviceable form of steel has been observed by employing synchrotron X-ray microtomography technique. Spatial resolution has been optimized using a test object with varying experimental conditions. Reasonably high resolution, which is close to the theoretical upper limit for the projection-type Xray tomography, has been achieved for a reasonably large specimen. Its application has made it possible to clearly observe a fatigue crack and its opening behavior in steel, and to demonstrate some quantitative mechanical evaluations.

W-Concentration 3D Mapping in SKH51 Steel by Dual-Energy K-Absorption Edge Subtraction Imaging

“…However, effect of scattering and diffraction on spatial resolution has been reported for imaging in steels. 11,12) Therefore, sample-to-detector distance may affect concentration brought by absorption edge subtraction imaging. Sample-to-detector distance was set 2, 20 and 65 mm, and then its effect was examined in this study.…”

“…Recently, utilizing stable high-energy beam and adjusting an effect of scattering and diffraction by sample-to-detector distance, however, the SR-CT with theoretically limited resolution is available in also steels, in which the sample is same size with aluminum alloy. 11,12) In this study, three-dimensional W-concentration mapping has been attempted in steels by applying absorption edge subtraction imaging with high energy X-ray in synchrotron radiation facility. The effect of sample-to-detector distance on spatial resolution is known in the SR-CT using high energy X-ray.…”

3D Fracture Behaviours in Dual-phase Stainless Steel

“…It has been reported that in a relatively high X-ray energy range, preferential forward scattering occurs, 12,14) which results in a remarkably low signal-tonoise ratio and spatial resolution when the sample-to-detector distance is less than 50 mm. 12,14) On the other hand, the ring artefacts observed above a sample-to-detector distance of 50 mm are gradually annihilated in the long-distance images. This may be attributable to degradation in the spatial resolution.…”

“…There have already been a number of attempts [8][9][10][11][12][13] to investigate microscopic damage mechanisms in DP steels by employing the recently improved high-resolution X-ray microtomography (hereinafter XMT) technique. 14) However, most of these studies have focused on simple damage evolution behaviour in continuum solids.…”

“…It has been reported by the present authors that the results of interface-based MTF calculations and those obtained with 3D test patterns showed reasonable agreement. 12) Noise was also measured in the phase-contrast images, by calculating the standard deviation inside given regions of interest (30 pixels × 30 pixels × 5 regions) for each image. In order to evaluate the efficiency of the single-distance phase retrieval technique, contrast was defined by substituting average grey values between the ferritic and austenitic phases.…”