Joe Kelleher | Rutherford Appleton Laboratory (original) (raw)

Papers by Joe Kelleher

Scientific Reports, 2019

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.

International Journal of Mechanical Sciences, 2019

International Journal of Mechanical Sciences. Changes resulting from the publishing process, such... more International Journal of Mechanical Sciences. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in

$Research paper thumbnail of Modern and Historical Engineering Components Investigated by Neutron Diffraction on ENGIN-X$

The ENGIN-X beamline is mainly used to determine residual strains/stresses deep within the interi... more The ENGIN-X beamline is mainly used to determine residual strains/stresses deep within the interior of bulk engineering components. It is mainly used by scientists and engineers for the development of modern engineering processes and structural integrity investigations. ENGIN-X diffraction and transmission mode can be a very useful tool to measure strain, phase transitions, texture and material composition in spatial resolution in historical or archaeological artifacts and modern materials. The complexity of the shapes and sizes of the samples measured on ENGIN-X varies significantly between experiments, and this required the development of better planning, simulation and control software, SScanSS. In this paper an overview of recent developments in strain scanning on ENGIN-X and a highlight of current scientific research are presented.

Angewandte Chemie (International ed. in English), Jan 18, 2018

Artifacts from the Egyptian grave goods of Kha and Merit preserved at the Museo Egizio in Turin w... more Artifacts from the Egyptian grave goods of Kha and Merit preserved at the Museo Egizio in Turin were studied through a combination of non-destructive and non-invasive neutron and gamma techniques (namely neutron imaging, neutron diffraction and prompt gamma activation analysis). The results provide unprecedented morphological reconstructions of the inner parts of the two alabaster and metallic vases and their isotopic and phase composition, thereby extending our knowledge of the hitherto unknown content of the vases and their functions.

Dental materials : official publication of the Academy of Dental Materials, May 6, 2017

Recent studies of the yttria partially stabilised zirconia-porcelain interface have revealed the ... more Recent studies of the yttria partially stabilised zirconia-porcelain interface have revealed the presence of near-interface porcelain nanovoiding which reduces toughness and leads to component failure. One potential explanation for these nanoscale features is thermal creep which is induced by the combination of the residual stresses at the interface and sintering temperatures applied during manufacture. The present study provides improved understanding of this important phenomenon. Transmission electron microscopy and small angle neutron scattering were applied to a sample which was crept at 750°C and 100MPa (sample C), a second which was exposed to an identical heat treatment schedule in the absence of applied stress (sample H), and a reference sample in the as-machined state (sample A). The complementary insights provided by the two techniques were in good agreement and log-normal void size distributions were found in all samples. The void number density was found to be 1.61μm(-2)...

$Research paper thumbnail of Visco-plasticity during in-situ cooling from solidification of a nickel-base single crystal superalloy using neutron diffraction$

Materials Science and Engineering: A, 2017

Where a licence is displayed above, please note the terms and conditions of the licence govern yo... more Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.

Acta Materialia, 2016

Link to publication on Research at Birmingham portal General rights Unless a licence is specified... more Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. • Users may freely distribute the URL that is used to identify this publication. • Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. • User may use extracts from the document in line with the concept of 'fair dealing' under the Copyright, Designs and Patents Act 1988 (?) • Users may not further distribute the material nor use it for the purposes of commercial gain. Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.

Neutron diffraction methods offer a direct measure of the elastic component of strain deep within... more Neutron diffraction methods offer a direct measure of the elastic component of strain deep within crystalline materials through precise characterisation of the interplanar crystal lattice spacing. The unique non-destructive nature of this measurement technique is particularly beneficial in the context of engineering design and archaeological materials science, since it allows the evaluation of a variety of structural and deformational parameters inside real components without material removal, or at worst with minimal interference. We review a wide range of recent experimental studies using the Engin-X materials engineering instrument at the ISIS neutron source and show how the technique provides the basis for developing improved insight into materials of great importance to applications and industry.

Journal of Applied Crystallography, 2014

A time-of-flight (TOF) neutron strain scanner is a white-beam instrument optimized to measure dif... more A time-of-flight (TOF) neutron strain scanner is a white-beam instrument optimized to measure diffractograms at precise locations within bulky specimens, typically along two perpendicular sample orientations. Here, a method is proposed that exploits the spatial resolution (∼1 mm) provided by such an instrument to determine in a nondestructive manner the crystallographic texture at selected locations within a macroscopic object. The method is based on defining the orientation distribution function (ODF) of the crystallites from several incomplete pole figures, and it has been implemented on ENGIN-X, a neutron strain scanner at the ISIS facility in the UK. This method has been applied to determine the texture at different locations of Al alloy plates welded along the rolling direction and to study a Zr2.5%Nb pressure tube produced for a CANDU nuclear power plant. For benchmarking, the results obtained with this instrument for samples of ferritic steel, copper, Al alloys and Zr alloys ...

Acta Materialia, 2013

The bainite transformation behavior after plastic deformation of austenite, i.e., ausforming was ... more The bainite transformation behavior after plastic deformation of austenite, i.e., ausforming was studied by in situ neutron diffraction and ex situ experiments, and the effects of ausforming temperature was made clear. Ausforming, at a low temperature (573 K) was found to accelerate bainite transformation and produce a characteristic microstructure, whereas at a high temperature (873 K), ausforming had little influence. The reason for the different results stems from the dislocation structure introduced in austenite; planar dislocations remaining on the active slip planes are believed to assist bainite transformation, accompanied by strong variant selection. The variant selection rule that focuses on Shockley partial dislocation was verified from electron backscatter diffraction results.

Materials Today, 2009

High-tech composites to ancient metals A variety of strain measurement techniques have evolved ov... more High-tech composites to ancient metals A variety of strain measurement techniques have evolved over the decades and are widely employed in experimental studies of deformation behaviour of materials and structures. The aim of strain measurement is to characterise the response to applied loads, particularly those corresponding to in-service loading, and to observe the response of objects so as to predict the integrity of various designs. This is the principal significance of strain analysis for structural design 1. Most strain measurement methods are only capable of measuring total strain increments. This is due to the fact that strain measurement Neutron diffraction methods offer a direct measure of the elastic component of strain deep within crystalline materials through precise characterisation of the interplanar crystal lattice spacing. The unique non-destructive nature of this measurement technique is particularly beneficial in the context of engineering design and archaeological materials science, since it allows the evaluation of a variety of structural and deformational parameters inside real components without material removal, or at worst with minimal interference. We review a wide range of recent experimental studies using the Engin-X materials engineering instrument at the ISIS neutron source and show how the technique provides the basis for developing improved insight into materials of great importance to applications and industry.

$Research paper thumbnail of PVP2011-57786 Study of Residual Stresses Heterogeneities in a Ring Norem Hardfaced Sample by Neutron Diffraction$

Iron-based hard-facing alloys, such as Norem, are considered to be good substitutes for Co-based ... more Iron-based hard-facing alloys, such as Norem, are considered to be good substitutes for Co-based ones where radiological activation is an issue. This work aims at studying residual stresses inside Norem02 Plasma Transferred Arc deposits. A standard test sample used by a valve manufacturer is taken as an example: it consists of a stainless steel (AISI 316L) disk with circular weld bead deposits of Norem hard-facing on both sides. Residual stresses were investigated using neutron diffraction on the ENGIN-X beam line. As expected, experimental results tends to indicate the welding overlap zones to be affected by reheating. Since previous works indicates quite limited metallurgical influence of high temperature re-heating on the deposited material, it is expected to be possible to capture this effect by further finite element modelling of the welding process, in order to study its influence on further in-service behaviour of valves.

Materials Research Proceedings

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licens... more Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under license by Materials Research Forum LLC.

The Excel spreadsheet contains an overview tab (“Neutron Data”) which contains the name of each n... more The Excel spreadsheet contains an overview tab (“Neutron Data”) which contains the name of each neutron diffraction run number, alongside the corresponding alloy and the temperature at which the data acquisition was carried out. The “Composition” tab contains the bulk composition of each alloy, as determined experimentally by SEM EDX. The “Precipitate Size” tab contains the areas of individual precipitates within each alloy. Between 128 and 345 precipitate areas are given for each alloy. The raw diffraction data are presented as individual ascii txt files for each run within the folder “Neutron Raw Data”. Each txt file is named as detailed in the Excel spreadsheet tab (“Neutron Data”). Each txt file contains four space-delimited columns of data (time-of-flight, d-spacing, intensity, intensity uncertainty).

New experimental approaches enabling in-depth study of granular mechanics using based neutron and... more New experimental approaches enabling in-depth study of granular mechanics using based neutron and xray based measurements of deformation and force transfer mechanisms at continuum-and grain-scales are presented.

Welding residual stresses exist in various welded structures such as ships and offshore structure... more Welding residual stresses exist in various welded structures such as ships and offshore structures. According to the load levels during operation, the as-welded residual stresses can be relaxed or redistributed. The elastic shakedown phenomenon can be considered as one of the reasons for the stress relaxation or redistribution. This work studies the redistribution of welding residual stresses during different levels of shakedown in a fillet-welded plate manufactured in line with ship design and welding procedures. Fillet welding was performed on a ship structural steel, DH36. The fillet welds were subjected to different levels of shakedown under tensile cyclic load. Neutron diffraction was used to measure residual stresses in these plates in the as-welded state and after elastic shakedown. A mixed hardening model in line with the Chaboche model was determined for both weld and base material. A shakedown limit analysis based on plastic work dissipation was developed as the shakedown ...

$Research paper thumbnail of Multiscale Analysis of Sand Under Load: A Novel Neutron Diffraction Based Experimental Approach$

The theoretical enrichment of continuum models for granular materials that take into account stra... more The theoretical enrichment of continuum models for granular materials that take into account strain localisation processes down to the microscale level (i.e., grain scale) is still ongoing and has always been highly dependent on the available experimental data and its quality. To this end, over the past few years there has been a great effort to develop new experimental approaches to provide missing information on the state of strain and stress deep inside granular media. Neutron Strain Scanning (NSS) is a diffraction–based technique that has been successfully used to determine the force/stress distribution in granular materials under load (e.g., [1-3]), by measuring the variations in interplanar distances of crystals (i.e., the crystallographic – or grain – strains). The work presented here is part of a PhD research project that involves the development of a specially designed plane strain loading apparatus for the realisation of NSS experiments on granular geomaterials, in combina...

$Research paper thumbnail of Mapping Grain Strains in Sand Under Load Using Neutron Diffraction Scanning$

Towards the improvement of the understanding of force/stress distribution in granular media under... more Towards the improvement of the understanding of force/stress distribution in granular media under load, a new experimental approach is suggested. Neutron diffraction, a non-conventional experimental technique, has been successfully used to map the evolution of intragranular strains in sand specimens loaded in a novel plane-strain apparatus. Representative preliminary results from recent experiments are presented, focusing on the correlation between the macro- and micro-scale response of the material, to highlight the potential of the experimental approach.

$Research paper thumbnail of Effects of heat treatment on residual stresses in the laser powder bed fusion of 316L stainless steel: Finite element predictions and neutron diffraction measurements$

Journal of Manufacturing Processes

Abstract Heat treatments are used in laser powder bed fusion (LPBF) to reduce residual stress and... more Abstract Heat treatments are used in laser powder bed fusion (LPBF) to reduce residual stress and improve service life. In order to qualify components for service, the degree of stress relaxation under heat treatment must be known. In this work, the effect of heat treatment on residual stress (RS) in LPBF 316L stainless steel was studied. Finite element (FE) models were developed to predict the RS distribution in specimens in the as-built state and subjected to heat treatment. The models simulated the thermo-mechanical LPBF build process, sample removal from the build plate and creep stress relaxation effects from a 2 h heat treatment at 700 ° C. The predictions were validated by neutron diffraction measurements in as-built and heat treated samples, in both build orientations. Large tensile RS of around 450 MPa were predicted at the vertical sample's outer gauge surfaces, balanced by high compressive stresses of similar magnitude at the centre. The residual stresses in the horizontal sample were significantly lower, by around 40%. The influence of sample removal from the base plate on the RS distribution was found to be strongly dependent on the sample orientation and geometry. The heat treatment preserved the unique microstructure of the LPBF process and reduced the peak RS by around 10% in the vertical sample and 40% in the horizontal sample. The FE model predictions were found in good agreement with the experimental measurements, thus providing an effective tool for RS predictions in LPBF components and proving the effectiveness of the heat treatment on RS relaxation.

Volume 6A: Materials and Fabrication, Jul 16, 2017

Flow forming is a near net shape process for manufacturing of dimensionally accurate hollow compo... more Flow forming is a near net shape process for manufacturing of dimensionally accurate hollow components such as shaft in gas turbines, that is currently at its development stage for aerospace industry. The process has several advantages such as reducing material wastage, extremely fast manufacturing time, and eliminating extra manufacturing processes such as machining. Due to the nature of this complicated cold deformation process, significant magnitude of residual stress is introduced into the component. Understanding the magnitude and distribution of residual stress is essential to tailor the flow forming process to achieve parts within dimensional tolerances and desired mechanical properties. The present research is aiming to explore the generation and evolution of residual stress at various stages of flow forming process in a tubular component made from martensitic 15Cr-5Ni stainless steel, using different techniques of neutron scattering, x-ray diffraction (XRD) and hole-drilling based on electronic speckle pattern interferometry (ESPI). Residual stress measurements were carried out in preformed and flow formed components at surface, near-surface and in the bulk of components using XRD, ESPI based hole-drilling and neutron diffraction techniques. These measurements were conducted at different levels of reduction in the thickness of the original part (i.e. after 20% and 40%), by applying identical forming parameters for all samples. The XRD results show significant change in hoop and axial residual stress levels with a reduction in the wall thickness. This is more pronounced for the axial component where the average stress switches from relatively high tensile (~ 450MPa) in the original part to significant compressive stress (~-600MPa) in the formed part, after 20% of reduction. The bulk residual stress components measured in the middle of thickness of the parts, using neutron scattering, show a general increase in the magnitude of residual stress by higher level of deformation (i.e. reduction in the wall thickness). The measured bulk stress components through the thickness were tuned to tensile after reducing the wall thickness by 40%. The results of XRD and neutron diffraction stress measurements suggest that the residual stress along the length of the samples (i.e. axial direction) is consistent with ±800 MPa and ±400 MPa after 20% and 40% reduction by forming process, respectively. The results of ESPI based hole-drilling show tensile hoop residual stress (≈600 MPa) and an abrupt fluctuation (i.e. tension-compressive-tension) in the axial residual stress near the surface of the part following flow forming. The stresses measured by ESPI based hole-drilling are complementary to the results of the XRD on surface and neutron diffraction in the bulk to reconstruct the residual stress profile form the surface through to the bulk.