Browsing by Author "Wu, X"

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    Corrigendum to “Effects of preheating and carbon dilution on material characteristics of laser-cladded hypereutectoid rail steels” [Mater. Sci. Eng. A 712 (2018) 548–563]
    (Elsevier, 2019-01-10) Lai, Q; Abrahams, R; Yan, W; Qiu, C; Mutton, PJ; Paradowska, AM; Fang, X; Soodi, M; Wu, X
    The authors regret that the scale bar was missing from Figure 7. This has now been corrected. Fig. 7. Unaffected rail substrate and corresponding HAZ of a typical rail-transverse sections at (a) left gauge corner, (b) middle section, (c) right gauge corner and (d) representative of the longitudinal sections for (i) Group 1-1L, (ii) Group 1-2L, (iii) Group 2-1L & (iv) Group 2-2L. Martensitic morphology (M=martensite) with white etching colour were detected in (c) and (d) of the (i) Group 1-1L and (ii) Group 1-2L. Copyright © 2021 Elsevier B.V.
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    Effects of preheating and carbon dilution on material characteristics of laser-cladded hypereutectoid rail steels
    (Elsevier, 2018-01-17) Lai, Q; Abrahams, R; Yan, W; Qiu, C; Mutton, PJ; Paradowska, AM; Fang, X; Soodi, M; Wu, X
    The impacts of preheating conditions and carbon dilution on the microstructural and mechanical properties of laser cladded rails using single and double cladding layers have been investigated for a hypereutectoid steel grades typically used under heavy haul conditions. The microstructures in the HAZ showed that formation of martensite, which has a detrimental effect on behaviour in wheel-rail contact, was successfully inhibited by increasing the length of the preheated region using a preheating temperature of 350 °C. Dilution of carbon from the hypereutectoid substrate was observed and its effect on the microstructures of the 410L ferritic stainless-steel deposits was investigated. The formation of ferrite in the 410L cladding layers was attributed to the very low carbon content, and no carbide formation was observed on boundaries of the ferritic grains. The thickness of dilution band was determined to be approximately equal to the thickness of the first cladding layer. Texture measurement obtained by EBSD showed a random trend owing to the formation of martensite in diluted bands. Strong solidification fibre texture was developed for double deposition, particularly in the second deposit. Mechanical characterization of the 410L deposits undertaken in terms of Vickers microhardness, shear and tensile yield strengths, and ultimate tensile and shear strengths were correlated with the observed microstructural morphologies. © 2017 Elsevier B.V.
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    Influences of depositing materials, processing parameters and heating conditions on material characteristics of laser-cladded hypereutectoid rails
    (Elsevier, 2019-01-01) Lai, Q; Abrahams, R; Yan, W; Qiu, C; Mutton, PJ; Paradowska, AM; Soodi, M; Wu, X
    The effects of different cladding materials, processing parameters and heating regimes on the underlying microstructural features and mechanical properties of laser-cladded premium rails were investigated by using a hypereutectoid rail grade as a substrate, which is extensively used in heavy-haul rail systems. Cladding materials of 410L, 420SS, Stellite 6 and Stellite 21 with single and double depositions were considered for the comparative study of different cladding materials and processing parameters. To ensure the constant thickness of the claddings for comparison purposes, transverse speed and powder feed rate were modified concurrently in the ranges of 1000–1200 mm/min and 3–4 RPM, respectively. Two heating conditions, i.e. preheating only (HTA) and a combination (HTB) of preheating and post weld heat treatment (PWHT) were applied after the preferable parameters for each cladding material were obtained. The most suitable cladding material for rail-wheel contact was established by assessing all crucial aspects, i.e. surface defects, hardness, microstructural and mechanical properties. Process parameters for each considered cladding material were determined to achieve no surface defects. For cladding layers, application of HTA was not able to significantly modify the microstructures of the deposits, whereas HTB was observed to cause severe cracks in Co-base alloys, i.e. Stellite 6 and Stellite 21. In the heat affected zones (HAZs), irrespective of the cladding materials, the formation of untempered martensite was not avoided by the application of preheating at 350 °C. Consequentially, cracking in the HAZ was observed. An uncracked and desirable microstructure in the HAZs was established using HTB, regardless of the depositing materials. The addition of a second layer did not change the thickness of the HAZs but refined the HAZ’s microstructures. Shear punch testing (SPT) and Vickers hardness testing were utilized to characterize mechanical properties for the considered cladding materials and good correlations with the obtained microstructural morphologies were shown. © 2018 Elsevier B.V.
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    Measuring residual stress in parts built using selective laser melting
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2013-12-02) Slingsby, T; Paradowska, AM; Law, M; Davies, C; Wu, X
    Selective Laser Melting (SLM) is an additive manufacturing technology that allows parts to be created from a laser melting metal powder in layer, rather than traditional methods such a machining and milling which removes waste from a bulk material. It is because of the greater efficiencies presented with this new technology that additive manufacturing is considered to be at the forefront of the third industrial revolution. SLM shows great promise to produce parts with unique geometry, minimal waste and short production times. While processing issues of balling, density and surface finish are gradually being improved, the issues of deformation and residual stress are major problems. For the SLM technology to be utilised, an understanding of the formation and control of residual stresses must be established. As the layer thickness of the manufacturing process is small, approx. 40μ, the techniques for analysing the residual stresses present must be carefully devised. A combination of neutron and synchrotron diffraction is to be used to analyse both macro and micro stresses in parts, utilising the advantages of both technologies. Experimental temperature profile logging and residual stress testing results are used alongside Finite Element Modelling (FEM) to quantify, predict and control these stresses.
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    Neutron measurements for additively manufactured components
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11) Chiu, L; Paradowska, AM; Wu, X
    Additive manufacturing is an exciting new approach to produce components that are not manufacturable using traditional methods. Coupled with its short CAD-to-product time, this method had been gaining significant attention. In particular, the application of Selected Laser Melting, which can process metals, is gaining popularity in application on aerospace components. Due to the numerous rapid thermal cycling in the melting process, strong residual stresses develop within the component being built, which leads to deformation and cracking. Neutron diffraction has sufficient penetration and measurement resolution to map the residual stresses variations within the component. Furthermore, the dimensional accuracy of the produced components is particularly difficult to measure due to the complex geometry. For example, the application of topology optimisation for weight reduction leads to a more organic shape as well as internal cavities but the component becomes more sensitive to geometric variations. Neutron CT is able to capture the geometry, particularly of internal cavities, as well as possible defects present. The combination of these two neutron measurement techniques provide a strong basis for improving the understanding of the SLM process and aid in the maturing of this process towards serial production.
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    Status of the compactlight design study
    (JACoW Publishing, 2019-05-19) D'Auria, G; Mitri, SD; Rochow, RA; Latina, A; Liu, X; Rossi, C; Schulte, D; Stapnes, S; Wu, X; Castañeda Cortes, HM; Clarke, J; Dunning, DJ; Thompson, N; Fang, W; Gazis, E; Gazis, N; Tanke, E; Trachnas, E; Goryashko, V; Jacewicz, M; Ruber, R; Taylor, G; Dowd, RT; Zhu, D; Aksoy, A; Nergiz, Z; Apsimon, R; Burt, G; Castilla, A; Priem, H; Janssen, X; Luiten, J; Mutsaers, P; Stragier, X; Alesini, D; Bellaveglia, M; Buonomo, B; Cardelli, F; Croia, M; Diomede, M; Ferrario, M; Gallo, A; Giribono, A; Piersanti, L; Scifo, J; Spataro, B; Vaccarezza, C; Geometrante, R; Kokole, M; Arnesano, J; Bosco, F; Ficcadenti, L; Mostacci, A; Palumbo, L; Dattoli, G; Nguyen, F; Petralia, A; Marcos, J; Marín, E; Muñoz Horta, R; Perez, F; Faus-Golfe, A; Han, Y; Bernhard, A; Gethmann, J; Calvi, M; Schmidt, T; Zhang, K; Esperante, D; Fuster, J; Gimeno, B; Gonzalez-Iglesias, D; Aicheler, M; Hoekstra, R; Cross, AW; Nix, L; Zhang, L
    CompactLight (XLS) is an International Collaboration of 24 partners and 5 third parties, funded by the European Union through the Horizon 2020 Research and Innovation Programme. The main goal of the project, which started in January 2018 with a duration of 36 months, is the design of an hard X-ray FEL facility beyond today’s state of the art, using the latest concepts for bright electron photo-injectors, high-gradient accelerating structures, and innovative shortperiod undulators. The specifications of the facility and the parameters of the future FEL are driven by the demands of potential users and the associated science cases. In this paper we will give an overview on the ongoing activities and the major results achieved until now. © The Authors - CC-BY 3.0 licence
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    Studies of magnetic structure of La1-xSrxMnO3 colossal magnetoresistive perovskites
    (Australian Institute of Physics, 2004-02-04) Finlayson, TR; Wu, X; Ersez, T; Schulz, JC
    This class of materials, based on the compound LaMnO3, continues to be the focus of attention because they exhibit colossal magnetoresistance (CMR) [1] which could lead to possible applications in magnetic recording and field sensors. In addition to the technological applications, the materials are important from a fundamental point of view due to the strong correlations between transport, structural and magnetic behaviour. The origin of the CMR effect has been attributed to the presence of magnetic polarons above the ferromagnetic ordering temperature, Tc. From recent research, using a combination of powder neutron diffraction, polarisation analysis and small-angle neutron scattering together with magnetic measurements, we present diffuse scattering, spin dynamics and lattice and magnetic correlations results for the La1-xSrxMnO3 (x=0.125 and 0.175) compounds. The diffuse scattering in the neutron diffraction patterns increases as the temperature approaches Tc from low temperature and continues to increase above Tc. The scattering peak in the forward direction above Tc (Tc
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    Towards the thermodynamic equilibrium of titanium aluminides after consolidation by back pressure equal channel angular pressing
    (ARC Centre of Excellence for Design in Light, 2007-12) Xu, W; Wu, X; Whitfield, R; Liss, KD; Buslaps, T; Yeoh, LA; Zhang, DL; Xia, K