Comparative Neutron and Synchrotron X-Ray Diffraction Studies to Determine Residual Stress on an As-Welded AA2024 Plate

2005 ◽  
Vol 490-491 ◽  
pp. 223-228 ◽  
Author(s):  
S. Ganguly ◽  
Michael E. Fitzpatrick ◽  
Lyndon Edwards
Keyword(s):  
Residual Stress ◽  
X Rays ◽  
X Ray Diffraction ◽  
Residual Stress Field ◽  
Good Correspondence ◽  
X Ray ◽  
Diffraction Geometry ◽  
Gauge Volume ◽  
Significant Difference ◽  
Similar Sample

The residual stress field in a VPPA welded AA2024 coupon sample was measured by neutron diffraction. A similar sample was measured using synchrotron X-rays to determine the inplane strain directions. The macrostrain obtained from both sources compares well in spite of the significant difference in gauge volume and diffraction geometry. The result confirms the repeatability of the weld process and also shows good correspondence between the two diffraction processes.

X-ray diffraction properties of curved crystal diffractors

1992 ◽  
Vol 50 (2) ◽  
pp. 1734-1735
Author(s):  
W. Z. Chang ◽  
D. B. Wittry
Keyword(s):  
Diffraction Theory ◽  
X Rays ◽  
Diffraction Image ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Bent Crystal ◽  
Diffraction Geometry ◽  
Crystal Parameter ◽  
Quantitative Procedure

Since Du Mond and Kirkpatrick first discussed the principle of a bent crystal spectrograph in 1930, curved single crystals have been widely utilized as spectrometric monochromators as well as diffractors for focusing x rays diverging from a point. Curved crystal diffraction theory predicts that the diffraction parameters - the rocking curve width w, and the peak reflection coefficient r of curved crystals will certainly deviate from those of their flat form. Due to a lack of curved crystal parameter data in current literature and the need for optimizing the choice of diffraction geometry and crystal materials for various applications, we have continued the investigation of our technique presented at the last conference. In the present abstract, we describe a more rigorous and quantitative procedure for measuring the parameters of curved crystals.The diffraction image of a singly bent crystal under study can be obtained by using the Johann geometry with an x-ray point source.

Determination of the Residual Stress Field around Scratches Using Synchrotron X-Rays and Nanoindentation

2010 ◽  
Vol 652 ◽  
pp. 25-30
Author(s):  
M.K. Khan ◽  
Michael E. Fitzpatrick ◽  
L.E. Edwards ◽  
S.V. Hainsworth
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Small Scale ◽  
X Rays ◽  
X Ray Diffraction ◽  
Residual Stress Field ◽  
Fine Grained ◽  
Load Displacement

The residual strain field around the scratches of 125µm depth and 5µm root radius have been measured from the Synchrotron X-ray diffraction. Scratches were produced using different tools in fine-grained aluminium alloy AA 5091. Residual stresses up to +1700 micro-strains were measured at the scratch tip for one tool but remained up to only +1000 micro-strains for the other tool scratch. The load-displacement curves obtained from nanoindentation were used to determine the residual stresses around the scratches. It was found that the load-displacement curves are sensitive to any local residual stress field present and behave according to the type of residual stresses. This combination of nanoindentation and synchrotron X-rays has been proved highly effective for the study of small-scale residual stresses around the features such as scratches.

Comparison of the hole-drilling and X-ray diffraction methods for measuring the residual stresses in shot-peened aluminium alloys

2005 ◽  
Vol 40 (2) ◽  
pp. 199-209 ◽  
Author(s):  
V Fontanari ◽  
F Frendo ◽  
Th Bortolamedi ◽  
P Scardi
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Surface Layer ◽  
Hole Drilling ◽  
X Ray Diffraction ◽  
Residual Stress Field ◽  
X Ray ◽  
Sources Of Uncertainty ◽  
Stress Profiles ◽  
Good Agreement

The incremental blind hole-drilling and the X-ray diffraction methods were used to measure the residual stress field introduced by shot peening in aluminium alloy 6082-T5 plates. Two peening treatments were selected to produce different depth extensions and peak values arising from different extents of plastic deformation in the surface layer. The results are discussed considering the various sources of uncertainty; in addition to the measuring technique, the effects of the surface treatment that usually induces a strong plastic deformation in the surface layer resulting in material work hardening and worsening of the surface morphology were considered. The residual stress profiles determined by the two methods showed quite good agreement for the two conditions, as regards the values both of the compressive peak and of the penetration depth. The present results provide mutual confirmation of the effectiveness of the two methods for the study of this class of materials.

Sin2ψ-based residual stress gradient analysis by energy-dispersive synchrotron diffraction constrained by small gauge volumes. I. Theoretical concept

2013 ◽  
Vol 46 (3) ◽  
pp. 610-618 ◽  
Author(s):  
M. Meixner ◽  
M. Klaus ◽  
Ch. Genzel
Keyword(s):  
Residual Stress ◽  
Energy Dispersive ◽  
Narrow Slit ◽  
X Rays ◽  
Synchrotron Diffraction ◽  
Near Surface ◽  
X Ray ◽  
Least Squares Fit ◽  
Gauge Volume ◽  
Information Depth

The influence of the gauge volume size and shape on the analysis of steep near-surface residual stress gradients by means of energy-dispersive synchrotron diffraction is studied theoretically. Cases are considered where the irradiated sample volume is confined by narrow-slit systems, in both the primary and the diffracted beam, to dimensions comparable to the `natural' 1/einformation depth τ1/eof the X-rays. It is shown that the ratio between τ1/e, defined by the material's absorption, and the immersion depthhGVof the gauge volume into the sample is the crucial parameter that shapes thedψhklor ∊ψhklversussin2ψ distributions obtained in the Ψ mode of X-ray stress analysis. Since the actual information depth 〈z〉GVto which the measured X-ray signal has to be assigned is a superposition of geometrical and exponential weighting functions, ambiguities in the conventional plot of the Laplace stressesversus〈z〉GVmay occur for measurements performed using narrow-slit configurations. To avoid conflicts in data analysis in these cases, a modified formalism is proposed for the evaluation of the real space residual stress profiles σ||(z), which is based on a two-dimensional least-squares fit procedure.

scholarly journals Influence of Layer Removal Methods in Residual Stress Profiling of a Shot Peened Steel Using X-Ray Diffraction

2014 ◽  
Vol 996 ◽  
pp. 175-180 ◽  
Author(s):  
Rasha Alkaisee ◽  
Ru Lin Peng
Keyword(s):  
Residual Stress ◽  
Chemical Etching ◽  
Stress Measurement ◽  
Diffraction Measurement ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer Removal ◽  
Compressive Stresses ◽  
The Difference

For X-Ray Diffraction Measurement of Depth Profiles of Residual Stress, Step-Wise Removal of Materials has to be Done to Expose the Underneath Layers to the X-Rays. this Paper Investigates the Influence of Layer Removal Methods, Including Electro-Polishing in Two Different Electrolytes and Chemical Etching, on the Accuracy of Residual Stress Measurement. Measurements on Two Shot-Peened Steels Revealed Large Discrepancy in Subsurface Distributions of Residual Stress Obtained with the Respective Methods. Especially, the Chemical Etching Yielded much Lower Subsurface Compressive Stresses than the Electro-Polishing Using a so Called AII Electrolyte. the Difference was Explained by the Influence of the Different Layer Removal Methods on the Microscopic Roughness.

Data Collection Requirements for the Analysis of Residual Stress in Polycrystalline Coatings

2006 ◽  
Vol 524-525 ◽  
pp. 795-800 ◽  
Author(s):  
Arnold C. Vermeulen ◽  
Detlev Götz
Keyword(s):  
Residual Stress ◽  
Data Collection ◽  
Single Crystal ◽  
Test Cases ◽  
X Ray Diffraction ◽  
Polycrystalline Specimen ◽  
X Ray ◽  
Data Collection Strategy ◽  
Diffraction Geometry ◽  
Complete Set

Residual stress in polycrystalline coatings can be determined by X-ray diffraction. The data collection requirements are summarized and evaluated in this paper. First, general requirements for stress measurements are described. Then, requirements related to the diffraction geometry and the specimen manipulation are considered. Finally, requirements with respect to specimen characteristics, including various coating-substrate combinations are presented. Polycrystalline coatings can be nanocrystalline, randomly orientated or highly textured. The substrates can be of any nature: amorphous, polycrystalline or single crystal. The complete set of requirements leads to a measurement advice for a particular coatingsubstrate specimen, which includes the choice of diffraction geometry and the data collection strategy. Based on two complementary test cases it is demonstrated that the set of rules is complete and that they can be applied to any type of polycrystalline specimen.

Adaptation of the X-Ray Diffraction Technique to the Analysis of Residual Stress in Carbo-Nitrided Steel Layers

2005 ◽  
Vol 490-491 ◽  
pp. 125-130
Author(s):  
Jean Michel Sprauel ◽  
H. Michaud
Keyword(s):  
Residual Stress ◽  
Carbon Content ◽  
Diffuse Scattering ◽  
Volume Fraction ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Quantitative Phase ◽  
Nitrided Steel ◽  
Stress Components

X-ray diffraction is used to analyse the fatigue behaviour of carbo-nitrided steel layers. Measurements are therefore carried out on the two major phases of the material, i.e. the martensite (a') and the retained austenite (g). On such gear material, X-ray residual stress evaluations are particularly difficult for three reasons. First, the studied material is multiphase. For that reason, in each phase, the stress component in the direction normal to the surface is non negligible. Second, the diffraction peaks obtained on the martensite are broadened, due to the overlap of different reflections of the tetragonal structure. Third, the material contains also carbide and nitride clusters, which lead to incoherent and diffuse scattering of X-rays thus making quantitative phase determination difficult. In our paper the methods used to solve these problems are presented. The development of a new quantitative phase analysis method which accounts for the variation of diffuse scattering of X-rays is shown first. The second part deals with an iterative micromechanical model implemented for the evaluation of the carbon content and the residual stress components of each phase. These methods are used for analysing the evolution with cycling fatigue of all the parameters derived from our enhanced analysis (phase volume fraction, carbon content, stress components, peak width).

X-ray diffraction at constant penetration depth – a viable approach for characterizing steep residual stress gradients

2008 ◽  
Vol 41 (2) ◽  
pp. 377-385 ◽  
Author(s):  
Thomas Erbacher ◽  
Alexander Wanner ◽  
Tilmann Beck ◽  
Otmar Vöhringer
Keyword(s):  
Residual Stress ◽  
Penetration Depth ◽  
Ground Surface ◽  
Shear Stresses ◽  
X Rays ◽  
X Ray Diffraction ◽  
Machined Surface ◽  
Near Surface ◽  
X Ray ◽  
Surface Residual Stresses

The experimental analysis of near-surface residual stresses by X-ray diffraction methods is based on measuring the spacings of lattice planes while the inclination ψ with respect to the surface plane is changed stepwise. A characteristic feature of conventional techniques is that the penetration depth of the X-rays is altered as inclination is varied. By simultaneously varying three different goniometer angles in a particular fashion, both the penetration depth and the measuring direction can be held constant while ψ is varied. Thus the normal and shear stresses can be derived from the sin2ψ plots by means of standard evaluation procedures developed for gradient-free stress states. The depth profile of residual stress is then obtainedviaLaplace transformation of the results from several stress measurements carried out at different penetration depths. In the present paper, the feasibility of this experimental approach for characterizing the strongly graded, non-equiaxed stress state existing at a machined surface is demonstrated. The results from constant-penetration-depth measurements on the ground surface of an engineering ceramic are compared with those from conventional sin2ψ measurements.

scholarly journals Direct Observation of Elastic and Plastic Strain Fields During Ductile Tearing of a Ferritic Steel

2016 ◽  
Author(s):  
Harry E. Coules ◽  
Graeme C. M. Horne ◽  
Matthew J. Peel ◽  
Sam J. Oliver ◽  
Derreck G. A. Van Gelderen ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Plastic Strain ◽  
Crack Tip ◽  
Image Correlation ◽  
Pressure Vessel Steel ◽  
X Ray Diffraction ◽  
Residual Stress Field ◽  
Ductile Tearing ◽  
X Ray

Residual and thermal stresses have a considerable effect on the process of brittle fracture. In addition to this, the effect of these stresses on elastic-plastic fracture is known to be significant. This is accounted for in structural integrity assessment methodologies such as R6 Rev 4 and BS 7910:2013 by introducing factors representing the interaction between primary and secondary stresses (those that do and do not contribute towards plastic collapse, respectively). The initiation of ductile tearing in a ferritic pressure vessel steel was studied experimentally. Energy-dispersive X-ray diffraction was used to determine lattice strains in the vicinity of a crack tip in modified compact tension specimens at incremental loading steps until the initiation of ductile tearing. The X-ray diffraction measurements allowed the stress field to be evaluated with a high spatial resolution. At the same time, the pattern of total strain at the surface of the specimen was observed using digital image correlation. Prior to the experiment, two samples were subjected to localised out-of-plane compression ahead of the crack tip to introduce a residual stress field and hence significant crack loading in the absence of external load. Stress and strain field data for cracked specimens, with and without a pre-existing residual stress field, indicated significant differences in the development of plastic strain up to the point of tearing initiation. It is shown that this can only be explained when both residual stress and prior material hardening are taken into account.

Residual Stress Analysis with Neutrons

1989 ◽  
Vol 166 ◽  
Author(s):  
Aaron D. Krawitz
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Analysis ◽  
X Rays ◽  
X Ray Diffraction ◽  
Paper Briefly ◽  
Sampling Depth ◽  
X Ray ◽  
Stress Studies ◽  
Residual Stress Analysis

ABSTRACTThe use of neutrons for the measurement of stress is complementary to and extends traditional x-ray diffraction methods to new types of problems. This is due to the lower absorption of neutrons compared to x-rays by most engineering materials, which increases the sampling depth from microns to millimeters. It is particularly suitable for triaxial macrostress gradients through the depth of engineering components and volumetric microstresses in composites. In addition, applied stress studies may also be performed. This paper briefly describes the nature of residual stresses, the use of diffraction for stress measurements, experimental aspects of the use of neutrons, and illustrative applications.

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