Investigation of Residual Stress/Strain and Texture in a Large Dissimilar Metal Weld Using Synchrotron Radiation and Neutrons

2013 ◽  
Vol 772 ◽  
pp. 193-199 ◽  
Author(s):  
Carsten Ohms ◽  
Rene V. Martins
Keyword(s):  
Synchrotron Radiation ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Large Scale ◽  
High Energy ◽  
X Ray Diffraction ◽  
Butt Weld ◽  
X Ray ◽  
Component Size ◽  
Thin Slice

Bi-metallic piping welds are frequently used in light water nuclear reactors to connect ferritic steel pressure vessel nozzles to austenitic stainless steel primary cooling piping systems. An important aspect for the integrity of such welds is the presence of residual stresses. Measurement of these residual stresses presents a considerable challenge because of the component size and because of the material heterogeneity in the weld regions. The specimen investigated here was a thin slice cut from a full-scale bi-metallic piping weld mock-up. A similar mock-up had previously been investigated by neutron diffraction within a European research project called ADIMEW. However, at that time, due to the wall thickness of the pipe, stress and spatial resolution of the measurements were severely restricted. One aim of the present investigations by high energy synchrotron radiation and neutrons used on this thin slice was to determine whether such measurements would render a valid representation of the axial strains and stresses in the uncut large-scale structure. The advantage of the small specimen was, apart from the easier manipulation, the fact that measurement times facilitated a high density of measurements across large parts of the test piece in a reasonable time. Furthermore, the recording of complete diffraction patterns within the accessible diffraction angle range by synchrotron X-ray diffraction permitted mapping the texture variations. The strain and stress results obtained are presented and compared for the neutron and synchrotron X-ray diffraction measurements. A strong variation of the texture pole orientations is observed in the weld regions which could be attributed to individual weld torch passes. The effect of specimen rocking on the scatter of the diffraction data in the butt weld region is assessed during the neutron diffraction measurements.

The structure of oxide glasses studied by high-energy x-ray diffraction

2020 ◽  
Vol 61 (6) ◽  
pp. 233-238
Author(s):  
S. Kohara ◽  
◽  
N. Umesaki ◽  
H. Ohno ◽  
K. Suzuya ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Structural Information ◽  
Structural Models ◽  
High Energy ◽  
Reverse Monte Carlo ◽  
Oxide Glasses ◽  
Neutron Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Approaches To Study

The use of high‑energy x‑ray diffraction techniques with the latest generation synchrotron sources has created new approaches to study quantitatively the structure of noncrystalline materials. Recently, this technique has been combined with neutron diffraction at pulsed source to provide more detailed and reliable structural information not previously available. This article reviews and summarises recent results obtained from the high energy x‑ray diffraction on several oxide glasses, SiO2, B2O3 and PbSiO3, using bending magnet beamlines at SPring‑8. In particular, it addresses the structural models of the oxide glasses obtained by the reverse Monte Carlo (RMC) modelling technique using both the high energy x‑ray and neutron diffraction data.

scholarly journals The migration mechanism of transition metal ions in LiNi0.5Mn1.5O4

2015 ◽  
Vol 3 (24) ◽  
pp. 13031-13038 ◽  
Author(s):  
Gui-Liang Xu ◽  
Yan Qin ◽  
Yang Ren ◽  
Lu Cai ◽  
Ke An ◽  
...  
Keyword(s):  
Transition Metal ◽  
Neutron Diffraction ◽  
Metal Ions ◽  
Transition Metal Ions ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Migration Mechanism

In situ high-energy X-ray diffraction and neutron diffraction were deployed to trace the migration of transition metal ions in LiNi0.5Mn1.5O4.

Three-dimensional welding residual stresses evaluation based on the eigenstrain methodology via X-ray measurements at the surface

2014 ◽  
Vol 03 (04) ◽  
pp. 1450023
Author(s):  
Masaru Ogawa
Keyword(s):  
Neutron Diffraction ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Strain Gauges ◽  
X Ray Diffraction ◽  
Stress Evaluation ◽  
X Ray ◽  
Residual Strains ◽  
Non Destructive ◽  
Evaluation Accuracy

In order to assure structural integrity for operating welded structures, it is necessary to evaluate crack growth rate and crack propagation direction for each observed crack non-destructively. Here, three dimensional (3D) welding residual stresses must be evaluated to predict crack propagation. Today, X-ray diffraction is used and the ultrasonic method has been proposed as non-destructive method to measure residual stresses. However, it is impossible to determine residual stress distributions in the thickness direction. Although residual stresses through a depth of several tens of millimeters can be evaluated non-destructively by neutron diffraction, it cannot be used as an on-site measurement technique. This is because neutron diffraction is only available in special irradiation facilities. Author pays attention to the bead flush method based on the eigenstrain methodology. In this method, 3D welding residual stresses are calculated by an elastic Finite Element Method (FEM) analysis from eigenstrains which are evaluated by an inverse analysis from released strains by strain gauges in the removal of the reinforcement of the weld. Here, the removal of the excess metal can be regarded as non-destructive treatment because toe of weld which may become crack starters can be eliminated. The effectiveness of the method has been proven for welded plates and pipes even with relatively lower bead height. In actual measurements, stress evaluation accuracy becomes poorer because measured values of strain gauges are affected by processing strains on the machined surface. In the previous studies, the author has developed the bead flush method that is free from the influence of the affecting strains by using residual strains on surface by X-ray diffraction. However, stress evaluation accuracy is not good enough because of relatively poor measurement accuracy of X-ray diffraction. In this study, a method to improve the estimation accuracy of residual stresses in this method is formulated, and it is shown numerically that inner welding residual stresses can be estimated accurately from the residual strains measured by X-ray diffraction.

Atomic-Scale Structure of Polymer-Route Si-C-O Fibers Observed by Synchrotron Radiation X-Ray Diffraction

2007 ◽  
Vol 352 ◽  
pp. 65-68 ◽  
Author(s):  
Kiyohito Okamura ◽  
Kentaro Suzuya ◽  
Shinji Kohara ◽  
Hiroshi Ichikawa ◽  
Kenji Suzuki
Keyword(s):  
Synchrotron Radiation ◽  
Network Structure ◽  
High Energy ◽  
Scale Structure ◽  
Atomic Scale ◽  
Intermediate Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Scale Structure ◽  
Amorphous Sic

The atomic scale structure of amorphous Si-C-O ceramics fibers produced from the pyrolysis of a polycarbosilane precursor has been investigated by X-ray diffraction using high-energy synchrotron radiation at SPring-8. First peak in the total correlation function T(r) of the amorphous and the heat-treated fibers is analyzed to consist of two contributions: Si-C (1.89 Å) and Si-O (1.61 Å) bonds. The coordination number of C and/or O around Si is about four. This suggests that the Si-C-O fibers basically have a network structure that consists of two tetrahedral units: SiC4 and SiO4. The local chemical and structural orders vary continuously in the materials from the disordered network structure of SiC4 and SiO4 tetrahedra (mixture of amorphous SiC and SiO2) to nanocrystals of SiC and SiO2, through the ternary Si-C-O solid solution which is believed to have an intermediate structure between the amorphous and crystalline states.

Experimental Comparison of In-Depth Residual Stresses Measured with Neutron and X-Ray Diffraction with a Numerical Stress Relaxation Correction Method

2017 ◽  
Vol 905 ◽  
pp. 131-136
Author(s):  
Bruno Levieil ◽  
Florent Bridier ◽  
Cédric Doudard ◽  
Vincent Klosek ◽  
David Thévenet ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Correction Method ◽  
Experimental Comparison ◽  
X Ray Diffraction ◽  
Element Analysis ◽  
Notched Specimen ◽  
X Ray

This study is an experimental comparison of in-depth X-ray diffraction residual stress measurements with neutron diffraction measurements. The goal is to evaluate the relevance of the Savaria-Bridier-Bocher [1] stress relaxation correction method. Neutron diffraction are performed on a bent notched specimen. Destructive X-ray diffraction is performed until 5.25mm below the surface by polishing the material. This polishing induces stress relaxation and X-ray diffraction results have to be corrected. For that purpose, a finite element analysis is realised and show good correlation with neutron measurements results. The application of the stress correction method improves the X-ray measurements especially after 2 mm below the surface. The differences between measured and corrected residual stresses from both diffraction techniques are analyzed and discussed.

Focusing Optics for High-Energy X-ray Diffraction

1998 ◽  
Vol 5 (3) ◽  
pp. 226-231 ◽  
Author(s):  
U. Lienert ◽  
C. Schulze ◽  
V. Honkimäki ◽  
Th. Tschentscher ◽  
S. Garbe ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
High Spatial Resolution ◽  
Dispersion Compensation ◽  
High Energy ◽  
Polycrystalline Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Momentum Resolution ◽  
Potential Applications ◽  
Band Pass

Novel focusing optical devices have been developed for synchrotron radiation in the energy range 40–100 keV. Firstly, a narrow-band-pass focusing energy-tuneable fixed-exit monochromator was constructed by combining meridionally bent Laue and Bragg crystals. Dispersion compensation was applied to retain the high momentum resolution despite the beam divergence caused by the focusing. Next, microfocusing was achieved by a bent multilayer arranged behind the crystal monochromator and alternatively by a bent Laue crystal. A 1.2 µm-high line focus was obtained at 90 keV. The properties of the different set-ups are described and potential applications are discussed. First experiments were performed, investigating with high spatial resolution the residual strain gradients in layered polycrystalline materials. The results underline that focused high-energy synchrotron radiation can provide unique information on the mesoscopic scale to the materials scientist, complementary to existing techniques based on conventional X-ray sources, neutron scattering or electron microscopy.

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