The Measurement of Residual Stresses by X-Ray Diffraction Techniques

James, M. R.; Cohen, J. B.

doi:10.21236/ada060349

Cited by 9 publications

(10 citation statements)

References 41 publications

(70 reference statements)

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“…For higher applied stresses we observe a systematic deviation of the stresses measured by the single exposure techniques from the dashed line denoting 1-to-1 correspondence with the two-tilt sin 2 ψ formulation. As noted before, this deviation might be caused by either (i) the elastic grain interaction stresses forming in response to the heterogeneous distribution of plastic flow in the microstructure, and the correspondent heterogeneous elastic residual strain distribution within the diffracting volumes, or (ii) the modification of any existing residual stresses due to plastic flow, or a combination of both effects [5]. This point should be taken into consideration in the selection of instruments/techniques for measurements on samples with complex residual stress distributions, as well as in the interpretation of the results.…”

Section: Resultsmentioning

confidence: 92%

Stress measurement using area detectors: a theoretical and experimental comparison of different methods in ferritic steel using a portable X-ray apparatus

et al. 2016

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Using area detectors for stress determination by diffraction methods in a single exposure greatly simplifies the measurement process and permits the design of portable systems without complex sample cradles or moving parts. An additional advantage is the ability to see the entire or a large fraction of the Debye ring and thus determine texture and grain size effects before analysis. The two methods most commonly used to obtain stress from a single Debye ring are the so called cos α and full-ring fitting methods, which employ least-squares procedures to determine the stress from the distortion of a Debye ring by probing a set of scattering vector simultaneously. The widely applied sin 2 ψ method, in contrast, requires sample rotations to probe a different subset of scattering vector orientations. In this paper we first present a description of the different methods under the same formalism and using a unified set of coordinates that are suited to area detectors normal to the incident beam, highlighting the similarities and differences between them. We further characterize these methods by means of in-situ measurements in carbon steel tube samples, using a portable detector in reflection geometry. We show that, in the absence of plastic flow, the different methods yield basically the same results and are equivalent. An analysis of possible sources of errors and their impact in the final stress values is also presented.

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Section: Resultsmentioning

confidence: 92%

Stress measurement using area detectors: a theoretical and experimental comparison of different methods in ferritic steel using a portable X-ray apparatus

et al. 2016

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“…The X-ray technique measures stresses indirectly by measuring the surface strain, which is indicated by the position of a diffraction peak for a crystal plane, oriented at various angles to the surfaces of a specimen [11]. Residual stresses were measured using peak shift sin 2 y technique with CrK α radiation.…”

Section: Methodsmentioning

confidence: 99%

Microstructure and mechanical property correlations in AA 6061 aluminium alloy friction stir welds

Reddy

Mastanaiah

Prasad

et al. 2009

Trans Indian Inst Met

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The influence of friction stir welding on the microstructure development and its role on residual stress distribution in the weldment and mechanical properties has been investigated. The study also focused on the impact of post weld heat treatment on the microstructure and mechanical properties as well as on residual stress distribution. The weld nugget region contained fine equiaxed grains as a result of thermomechanical working. Hardness survey showed that nugget region is soft due to precipitates dissolution. Weld joint exhibited lower strength as compared to the parent metal. Post weld Solution Treatment and Aging (STA) of longitudinal welds resulted in strength and ductility equivalent to that of parent metal while transverse weld tensile strength and ductility were lower than that of parent metal even after post weld STA. Residual stress distribution profiles across the weld region are asymmetric with respect to weld centerline, with the largest residual; stress gradients occurring on the advancing side of the weld. Within the region inside the shoulder diameter, residual stress is entirely compressive. Welds exhibited tensile residual stresses in post weld STA condition

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“…Due to the low dose tested in this experiment, the diffraction elastic constants were assumed to be unchanged by irradiation since it is likely that point defects and dislocation loops would be present at these low doses and therefore would not significantly alter the interplanar response. In the standard case of residual stress measurement in plastically deformed surfaces using the Sin 2 ψ method, such as those achieved using tooling or shot peening, the presence of dislocations does not alter the diffraction elastic constants 73 , so can be thought of as insensitive to this type of defect. However, in the case of materials irradiated to high doses, such as those leading to the formation of voids, precipitation and significant microstructural modification, the diffraction elastic constants would need to be calculated for this condition.…”

Section: Methods 1: Xrd and Dic Monitoring Of Plastic Deformationmentioning

confidence: 99%

Novel Methods for Recording Stress-Strain Curves in Proton Irradiated Material

Smith

Garner

Lunt

et al. 2020

Sci Rep

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proton irradiation is often used as a proxy for neutron irradiation but the irradiated layer is typically <50 μm deep; this presents a problem when trying to obtain mechanical test data as a function of irradiation level. two novel methodologies have been developed to record stress-strain curves for thin proton-irradiated surface layers of SA-508-4N ferritic steel. In the first case, in-situ loading experiments are carried out using a combination of X-ray diffraction and digital image correlation on the near surface region in order to measure stress and strain, thereby eliminating the influence of the non-irradiated volume. the second approach is to manufacture small-scale tensile specimens containing only the proton irradiated volume but approaching the smallest representative volume of the material. this is achieved by high-speed focused ion beam (fiB) milling though the application of a Xe + plasma-fiB (PFIB). It is demonstrated that both techniques are capable of recording the early stage of uniaxial flow behaviour of the irradiated material with sufficient accuracy providing a measure of irradiation-induced shift of yield strength, strain hardening and tensile strength.The limited penetration depth of proton irradiation makes measurement of mechanical properties difficult using established techniques 16,17 . Over the last decade, the use of Ga + focussed ion beam (FIB) instruments has allowed for the preparation of small scale samples from proton irradiated layers 18-23 . The mechanical properties of these samples are then tested using a MEMS chip or piezo-actuated test rig without contributions from the non-irradiated volume. This development has allowed studies to take advantage of the increased dose rates and to probe changes in properties previously only attainable using indentation testing [24][25][26][27][28] . However, milling rates are slow because for Ga + FIBs the useable milling currents are limited due to the point source of Ga + ions. Consequently, specimen diameters achievable in a practical time frame are limited to ~10 µm. For most engineering materials, the maximum achievable scale is therefore in the order of single to only a few grains. Hence, the technique is most applicable to single and bi-crystal investigations rather than representing the bulk response of polycrystalline specimens. It has been demonstrated that small scale specimens exhibit an increased hardening inversely proportional to specimen diameter [29][30][31][32][33] . In order to obtain a bulk response, specimens require a minimum length scale sufficient to overcome size reduction effects. The optimum specimen size would have the smallest representative volume (SRV), which would retain the benefits of scale reduction whilst exhibiting bulk behaviour 34 .Recent work by the authors has explored two techniques to increase the sampling volume in low energy proton irradiated samples prepared for mechanical testing 35,36 . The first, an adaptation of the technique outlined by Foecke et al. 37 , combines in-situ X-ray diffraction ...

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The Measurement of Residual Stresses by X-Ray Diffraction Techniques

Cited by 9 publications

References 41 publications

Stress measurement using area detectors: a theoretical and experimental comparison of different methods in ferritic steel using a portable X-ray apparatus

Stress measurement using area detectors: a theoretical and experimental comparison of different methods in ferritic steel using a portable X-ray apparatus

Microstructure and mechanical property correlations in AA 6061 aluminium alloy friction stir welds

Novel Methods for Recording Stress-Strain Curves in Proton Irradiated Material

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