Browsing by Author "Luzin, V"
Now showing 1 - 20 of 85
Results Per Page
- ItemAnalysis of compositionally ungraded FGM analogues: Neutron diffraction measurements of residual stress and mechanical testing of pressure sintered Mo-Y2O3 and Mo-Al2O3(Karlsruhe Institute of Technology, 2015-05) Saleh, M; Chavara, D; Toppler, K; Alexander, J; Ruys, AJ; Kaveh, K; Luzin, VFunctionally graded materials (FGMs) are a type of naturally inspired composite materials whose properties (e.g. microstructure, chemical or phase composition) vary over one or more dimensions. The FGMs were first proposed as an advanced engineering material in 1972 and research into application for Biomaterials, Aerospace, Chemical Plants, Mining, and Building material commodities[1, 2] is ever present. Within the nuclear industry FGMs can be engineered to effectively resist corrosion, radiation and are a potential choice for nuclear reactor components e.g. first wall for fusion reactors and fuel pellets. Additionally FGM’s have been proposed as potential plasma facing components (PFC) whereby the PFC would gradually vary from a refractory material (tungsten, plasma face) to a heat sink material (copper, coolant side). In the case of a metal-ceramic FGM, the composite mates the strength and ductility of a metal with the hardness and toughness of a ceramic [3-5]. The authors have sought to elucidate the development of residual stress in FGMs using neutron measurements on the Kowari Strain Scanner, ANSTO for the Mo-Y2O3 and Mo-Al2O3 system. Due to their extreme gradients FGM’s are not optimal for fast neutron measurements due to the high spatial resolution requirements and long measurement times. An alternative approach was employed to examine compositionally ungraded analogues of varying metal-ceramic ratios. All sample were manufactured using constituent powders, mixed and subsequently sintered using a hot press with close monitoring of the sintering curve. Optical microscopy and scanning electron microscopy were used to look at the resultant samples to observe the grain growth and the defect-like cracks attributable to the thermally induced stresses. Relaxation due to micro cracking and micro-fracturing are evaluated in light of the neutron residual stress measurements and mechanical strength measurements of : (a) bending stiffness using a three point bend tests, (b) bulk modulus through GrindoSonic techniques and (c) statistically averaged micro-hardness. Further evaluation of the residual stress is done through comparison between established analytical models, neutron diffraction and preliminary FEA. The major contribution of residual stress are further realised and evaluated in light of the interfacial instabilities present and the appropriate ways to optimise the thermal protection characteristics of a compositional gradient.
- ItemAnalysis of the residual stress and bonding mechanism in the cold spray technique using experimental and numerical methods(Elsevier, 2014-08-15) Saleh, M; Luzin, V; Spencer, KIn the current study, numerical solutions were used to simulate multi-particle deposition in the cold spray (CS) process, and to investigate some of the physical attributes of the deposition process of AA-6061-T6 particles deposited on an AA-6061-T6 substrate. Earlier experimental results are presented, with varying substrate and cladding combination; a subset of these results is analysed using single particle impact simulation, a more traditional approach in simulations of cold spray, and the smooth particle hydrodynamic (SPH) formulation to simulate multi-particle deposition. In a single particle impact simulation, a strong correlation between temperature and plastic deformation of the CS particles during the deposition process was found. The authors were able to correlate the onset of adiabatic shear instability with pronounced reduction in the flow stress with an inversely proportional relation exhibited for both temperature rise and plastic deformation. In the simulation of multiple particle impact, 400 particles, several bulk characteristics were extracted as through-thickness functions: density, equivalent plastic strain and stress profile. Stress profile from the simulation was contrasted against neutron diffraction measurements of residual stress, along with the analytical model of Tsui and Clyne, and is shown to achieve good correlation and providing validation of the results of simulations. Furthermore it was found that these stresses originate from a delicate balance between (a) the strain rate hardening and thermal softening and (b) the shot peening effects induced by the impact of CS particles. Analysis of particle morphologies in the simulation suggests a strong influence of temperature rise at the periphery of CS particles during deposition and dynamic recrystallization with the strong jetting of molten metal allowing for inter particle mixing and substrate adhesion. © 2014, Elsevier B.V.
- ItemAnalysis of the residual stress in ARMOX 500T armour steel and numerical study of the resultant ballistic performance(Materials Research Forum LLC, 2016-07-03) Saleh, M; Luzin, V; Kariem, MM; Ruan, DArmour steels and their response to ballistic and blast threats have been dutifully studied in light of increased conflict and advances in protection levels. The strength of these quenched and tempered martensitic steels is a result of micro alloying, Ni Cr, and Mn, a combination of hot and cold rolling of the steel and proprietary heat treatments. The resultant hardness and toughness are pronounced and are reflected in the ballistic performance of the steel, although the role of the residual stress (RS) has not been unambiguously confirmed. To elucidate the effects of the RS on ballistic properties a two-step study was performed. Firstly, stress measurements were carried out on ARMOX 500T on the RS diffractometer KOWARI at ANSTO on a 8.3 mm thick plate. Stress components in rolling and transverse directions were calculated. Using the experimentally measured stress profiles as an input, numerical analysis was carried out on the ballistic response of the plate to the 7.62 mm APM2 round. Since numerical modelling inherently require the evaluation of material properties at elevated strain rates, to gauge the impact driven stress-strain response, the material’s responses were derived using experiments utilising quasi-static testing and instrumented high strain rate experiments using the Split Hopkinson Pressure Bar (SHPB) at Swinburne University, Australia. These experimentally determined high strain rate data were incorporated into the Johnson-Cook (J-C) computational models for the flow stress along with literature sourced parameters for the failure model of the plate. Analysis of the two starting conditions, with and without residual stress, allows the authors to draw some conclusion about the role of the residual stress on the ballistic performance of ARMOX 500T armour steel. © 2017 The Authors.
- ItemAnisotropic behaviours of LPBF Hastelloy X under slow strain rate tensile testing at elevated temperature(Elsevier B. V., 2022-06) Yu, CH; Peng, RL; Lee, TL; Luzin, V; Lundgren, JE; Moverare, JTo improve the understanding of high temperature mechanical behaviours of LPBF Ni-based superalloys, this work investigates the influence of an elongated grain structure and characteristic crystallographic texture on the anisotropic tensile behaviours in LPBF Hastelloy X (HX) at 700 °C. Two types of loading conditions have been examined to analyse the anisotropy related to the building direction (BD), including the vertical loading (loading direction//BD) and the horizontal loading (loading direction ⊥ BD). To probe the short-term creep behaviours, slow strain rate tensile testing (SSRT) has been applied to address the strain rate dependent inelastic strain accumulation. In-situ time-of-flight neutron diffraction upon loading was performed to track the anisotropic lattice strain evolution in the elastic region and the texture evolution in the plastic region. Combined with the post microstructure and fracture analysis, the anisotropic mechanical behaviours are well correlated with the different microstructural responses between vertical and horizontal loading and the different strain rates. A better creep performance is expected in the vertical direction with the consideration of the better ductility and the higher level of texture evolution. © 2022 The Authors. Published by Elsevier B.V. Open access article under the CC BY licence.
- ItemAn assessment of the effect of cutting welded samples on residual stress measurements by chill modelling(SAGE Publications, 2010-08-01) Law, M; Kirstein, O; Luzin, VIn making residual stress measurements in welds, a common problem is that the samples are often cut before measurement, which may alter the stresses. To estimate the effects of cutting, a simplified method of modelling residual stresses in welds was developed, known as chill modelling, which requires limited material data and no welding process data. The method can be performed with elastic finite element analysis. The method does not predict the value of the stresses, just the relative reduction that occurs after cutting. The method was validated against published synchrotron measurements of welded plates, which were cut and remeasured a number of times. For welded plates only, an empirical equation was developed that predicts the change in stress after cutting. © 2010, SAGE Publications
- ItemBenchmarking studies of the MPISI material science diffractometer at SAFARI-1(Materials Research Forum LLC, 2016-07-03) Venter, AM; Marais, D; Luzin, VThe measurement performance of the new material science instrument MPISI at the SAFARI-1 research reactor in South Africa has been comprehensively benchmarked for strain scanning applications. In addition to the traditional VAMAS Ring and Plug specimen, the benchmarking was extended to a project that required sub-millimeter spatial resolution. For the latter the MPISI performance has been compared with experimental investigations on the same sample set at the KOWARI instrument at ANSTO. Overall, good data quality and agreement have been observed between the two instruments.© The Authors
- ItemBragg-edge elastic strain tomography(Engineers Australia, 2017-11-27) Wensrich, CM; Gregg, AWT; Hendriks, JN; Aggarwal, R; Tremsin, AS; Shinohara, T; Luzin, V; Meylan, MH; Kisi, EH; Kirstein, OTime-of-flight neutron imaging has now progressed to the point where high-resolution energy-resolved imaging is possible. Among many other applications, this technology allows the imaging of elastic strain fields within polycrystalline solids using a geometry identical to a traditional radiograph. 3D strain tomography from measurements such as these has been a current topic of research over the past decade. The authors recently solved this tomography problem and provided a reconstruction algorithm for the set of all systems subject to external loads in the absence of residual or eigenstrain. In this paper we provide an overview of the recent experiment carried out at the J-PARC pulsed neutron source in Japan focused on demonstrating this algorithm. This now represents the first-ever practical demonstration of Bragg-edge neutron transmission strain tomography in a non-axisymmetric system. The results of the experiment are presented along with the validation of the reconstructed field through Digital Image Correlation and traditional constant wavelength neutron strain scanning within the Australian Centre for Neutron Scattering at ANSTO. An outlook on potential strategies for reconstruction in the general case is also provided. © 2017 Engineers Australia
- ItemCarbide composition and stress measurement in ethylene pyrolysis tubes(Australian Institute of Physics, 2010-02-05) Stevens, KJ; Ingham, B; Ryan, M; Luzin, V; Cheong, KEthylene is important in the production of polyethylene, used in thin film packaging, piping and cable sheathing. It is produced by steam cracking of naptha, LPG or ethane at temperatures around 950°C at high flow velocities. Carburisation of ethylene pyrolysis tubes (typically of nominal composition 31%Fe, 37%Ni and 25%Cr) causes a loss in weldability, corrosion resistance and ductility, and provides a source of micro-cracking. Plant operators prefer to replace tubes at planned outages and are interested in remaining life assessments assisted by description and modelling of the progress of carburisation. The powder diffraction beamline at the Australian Synchrotron has been used to radially scan mounted and polished tube sections prepared from ex-service carburised tubes. Radial dependence of carbide phases in the tubes is being quantified using Bruker TOPAS software for whole pattern line fitting. Composition analysis and microscopy is being used to create a representative microstructure in Abaqus Finite Element Analysis (FEA) models and to interpret non-destructive eddy current measurements  of carburisation. The austenite diffracting planes give a peak shift response to stress that is anisotropic and is being interpreted with FEA based crystal plasticity models. Neutron diffraction at the Kowari beamline at OPAL (Open Pool Australian Lightwater reactor) was used to measure strain in unsectioned tubes at room temperature. This was compared to FEA models of the strain created by differential thermal expansion between carbide phases and austenite, assuming creep relaxation at normal tube operating temperature.
- ItemCharacterization of the residual stresses introduced by a new joining method in diamond and tungsten carbide composites(Curran Associates, Inc., 2019-05-29) Lavigne, O; Luzin, V; Mendez, M; Malik, AS; Rosas-Carrasco, O; Salvemini, FIn this work, a co-sintering method was used to attach diamond to cemented carbide composites. The joining method consists of sintering a green part (ring) of cemented carbide (CC) around a thermally stable diamond composite (TSDC) part (plug) to radially contain it. During the sintering step, the green body shrinks to a controlled level and therefore forms interference fit between the two parts (mismatch between the inner diameter (ID) of the CC ring and the outer diameter (OD) of the TSDC cylinder). The residual stresses induced by this process as well as the bond strength between the CC and the TSDC parts were quantitatively evaluated. It is shown that the interface pressure between the two parts, and the level of residual stresses, increased with increase in the designed interference fit, as well as with the increase of the ID/OD ratios of the CC ring. For the chosen material combination (cemented carbide ring comprised 90 vol% WC and 10 vol% Co with medium coarse WC grains; diamond composite plug comprised 84 vol% diamond and 16 vol% SiC), the values of the hoop stresses at the interface in the CC ring measured by neutron diffraction was determined to be between 150 MPa and 550 MPa, depending on the ID/OD ratio. It was also found that for a given ID/OD ratio, the increase of the designed interference fit had little effect on that attained due to the plastic deformation of the cemented carbide material at the interface during the sintering (dynamic) process. A mechanical bond around 60 MPa was nevertheless achieved.
- ItemCharacterization of thermally stable diamond composite material(Scientific.Net, 2014-02-01) Luzin, V; Boland, JN; Avdeev, M; Li, XSDiamond composite materials are being used increasingly in cutting tools for both the mining and manufacturing industries. Except for the low pressure CVD and SPS methods, most SiC based diamond composites are produced under high pressure and high temperature (HPHT). The dominant binder phase is SiC and these composites are classed as thermally stable and are referred to as TSDC (thermally stable diamond composite). TSDC composites are produced by reactive sintering either within the diamond stability field, ~1500°C and ~5.5 GPa, or in the graphite phase field at ~1550°C and ~2 - 3.5 GPa as originally patented by Ringwood. Unlike the traditional polycrystalline diamond composite (PCD) that use Co as the binder phase and operate under restricted temperature conditions, usually less the 800°C, TSDC is Co-free allowing the operational temperature range for TSDC to be extended substantially. Extensive experimental research has been conducted at the CSIRO (Commonwealth Scientific & Industrial Research Organization) Rock Cutting Laboratory to assess the quality of TSDC products through a series of in-house tests that have been developed (abrasive wear test, compressive and shear testing) to facilitate their use in the mining industry. The focus is to prevent TSDC from premature failures in drilling and cutting operations. Since the wear resistance and performance in general, of TSDC cutting elements are strongly dependent on the phase composition, phase distribution (microstructures) and phase interaction (microstresses), detailed studies of TSDC have been undertaken using optical, SEM (with EDS and CL), Raman microscopy and radiographic imaging of macro defects as well as x-ray and neutron diffraction. Residual stress measurements were made using the neutron diffractometer Kowari at OPAL research reactor in the diamond and SiC phases in two TSDC samples. The microstresses that developed in these phases as a result of quenching from high sintering pressure and temperature and the mismatch of the thermo-mechanical properties of SiC matrix and diamond inclusions were evaluated. The matrix-inclusion concept has also been used to calculate stress partition in the phases of the TSDC products that can be directly comparable with the experimental data and give clearer interpretation of the experimental results. © 2021 by Trans Tech Publications Ltd.
- ItemComprehensive numerical analysis of a three-pass bead-in-slot weld and its critical validation using neutron and synchrotron diffraction residual stress measurements(Pergamon-Elsevier Science LTD, 2012-05-01) Muránsky, O; Smith, MC; Bendeich, PJ; Holden, TM; Luzin, V; Martins, RV; Edwards, LThe current paper presents a finite element simulation of the residual stress field associated with a three pass slot weld in an AISI 316LN austenitic stainless steel plate. The simulation is split into uncoupled thermal and mechanical analyses which enable a computationally less expensive solution. A dedicated welding heat source modelling tool is employed to calibrate the ellipsoidal Gaussian volumetric heat source by making use of extensive thermocouple measurements and metallographic analyses made during and after welding. The mechanical analysis employs the Lemaitre-Chaboche mixed hardening model. This captures the cyclic mechanical response which a material undergoes during the thermo-mechanical cycles imposed by the welding process. A close examination of the material behaviour at various locations in the sample during the welding process, clearly demonstrates the importance of defining the correct hardening and high temperature softening behaviour. The simulation is validated by two independent diffraction techniques. The well-established neutron diffraction technique and a very novel spiral slit X-ray synchrotron technique were used to measure the residual stress-strain field associated with the three-pass weld. The comparison between the model and the experiment reveals close agreement with no adjustable parameters and clearly validates the used modelling procedure. Crown Copyright (C) 2011 Elsevier Ltd.
- ItemCultural heritage project at Australian Nuclear Science and Technology Organisation (ANSTO)(Springer Nature, 2022-01-25) Salvemini, F; White, R; Levchenko, VA; Smith, AM; Pastuovic, Z; Stopic, A; Luzin, V; Tobin, MJ; Puskar, L; Howard, DL; Davis, J; Avdeev, M; Gatenby, S; Kim, MJ; Grazzi, F; Sheedy, K; Olsen, SR; Raymond, CA; Lord, C; Richards, C; Bevitt, JJ; Popelka-Filcoff, RS; Lenehan, CE; Ives, S; Dredge, P; Yip, A; Brookhouse, MT; Austin, AGThe Australian Nuclear Science and Technology Organization (ANSTO) is the home of Australia’s most significant landmark and national infrastructure for research. ANSTO operates one of the world’s most modern nuclear research reactors, OPAL; a comprehensive suite of neutron beam instruments; the Australian Synchrotron; the Electron Microscope Facility; and the Center for Accelerator Science. Over the years, the suite of nuclear methods available across ANSTO’s campuses has been increasingly applied to study a wide range of heritage materials. Since 2015 the strategic research project on cultural heritage was initiated in order to promote access to ANSTO’s capabilities and expertise, unique in the region, by cultural institution and researchers. This chapter offers a compendium of ANSTO nuclear capabilities most frequently applied to cultural heritage research. A series of innovative, interdisciplinary, and multi-technique studies conducted in close collaboration with Australian museums, institutions, and universities is also showcased. It includes research on dating Aboriginal Australian rock art and fingerprinting the sources of ochre pigments; rediscovering the technological knowledge in the making of early coinage and ancient weapons; virtually unwrapping the content of votive mummies from ancient Egypt; and investigating and restoring the original layer of a painting that can be explored by the museum audience in a novel type of exhibition based on an immersive, interactive, and virtual environment. © 2022 Springer Nature Switzerland AG
- ItemDeformation textures in the principal slip zone of the Chelungpu fault, Taiwan, and its implication for stress change during the seismic cycle(American Geophysical Union, 2018-12-10) Kuo, LW; Luzin, V; Chen, PC; Yeh, EC; Ma, KFThermal pressurization is postulated for fault lubrication during seismic ruptures and leads catastrophic natural disasters. One recent example includes the active Chelungpu fault resulted in 1999 Mw 7.6 Chi-Chi earthquake in Taiwan. Efforts to improve seismic hazard assessment in such a region require a quantitative understanding of fault dynamics during earthquake generation. The principal slip zone (PSZ) of the active Chelungpu fault, showing rapid shear heating of fault gouge, might preserve stress magnitude accommodated the thermal pressurization during the earthquake. Here we conduct in situ neutron texture analysis for determining both recent and ancient histories of rocks because deformation events like earthquakes are imprinted in the crystallographic grain orientation. Overall, 12 samples collected from the fresh fault core, which represent almost continuous scan across the fault, were analyzed with the neutron experiment on KOWARI, Australia. Two distinguished types of the preferred orientation were found: (1) the textures with c-axis orientations predominantly parallel to bedding planes, which are found in the most of sedimentary rocks, are compaction-related and this is observed for the most analyzed samples; (2) the textures of sample 5 and 10, which are identified as Chi-Chi PSZ, demonstrate quite different deformation history with different orientation of the principal stresses that plausibly resulted from thermal pressurization process within the PSZ. Integrating these observations with the multiple stress inversion method, we obtain the change in stress field and it magnitude related to the end of the fault rupture. Since thermal pressurization process is proposed as a widespread process for earthquake generation and propagation, we suggest that the investigation of gouge orientation of a fault offers the opportunity to study the stress drop and recovery during the seismic cycle.
- ItemDynamics of ice mass deformation: Linking processes to rheology, texture, and microstructure(American Geophysical Union, 2013-10-01) Piazolo, S; Wilson, CJL; Luzin, V; Brouzet, C; Peternell, MPrediction of glacier and polar ice sheet dynamics is a major challenge, especially in view of changing climate. The flow behavior of an ice mass is fundamentally linked to processes at the grain and subgrain scale. However, our understanding of ice rheology and microstructure evolution based on conventional deformation experiments, where samples are analyzed before and after deformation, remains incomplete. To close this gap, we combine deformation experiments with in situ neutron diffraction textural and grain analysis that allows continuous monitoring of the evolution of rheology, texture, and microstructure. We prepared ice samples from deuterium water, as hydrogen in water ice has a high incoherent neutron scattering rendering it unsuitable for neutron diffraction analysis. We report experimental results from deformation of initially randomly oriented polycrystalline ice at three different constant strain rates. Results show a dynamic system where steady-state rheology is not necessarily coupled to microstructural and textural stability. Textures change from a weak single central c axis maxima to a strong girdle distribution at 35° to the compression axis attributed to dominance of basal slip followed by basal combined with pyramidal slip. Dislocation-related hardening accompanies this switch and is followed by weakening due to new grain nucleation and grain boundary migration. With decreasing strain rate, grain boundary migration becomes increasingly dominant and texture more pronounced. Our observations highlight the link between the dynamics of processes competition and rheological and textural behavior. This link needs to be taken into account to improve ice mass deformation modeling critical for climate change predictions. © 2013, American Geophysical Union.
- ItemEffect of laser clad repair on the fatigue behaviour of ultra-high strength AISI 4340 steel(Elsevier, 2014-06-12) Sun, SD; Liu, Q; Brandt, M; Luzin, V; Cottam, R; Janardhana, M; Clark, GAThe fatigue behaviour of an ultra-high strength steel (>1800 MPa) was evaluated to assess the potential of using laser cladding as a repair tool for such steels in aeronautical structural applications. AISI 4340 and AerMet 100 steel powder were used to clad over a grind-out region in an AISI 4340 steel substrate using a 2.5 kW ND:YAG laser. Post-clad heat treatment (PCHT) was also investigated. Results showed very poor tensile properties and significantly reduced fatigue life of the AISI 4340 as-clad with a very high hardness and brittle fracture in the clad and HAZ zone. Residual stress results showed a compressive residual stress in the clad region and tensile residual stress in the HAZ. Changing the alloy of the clad layer to AerMet 100 steel, as well as applying a PCHT process, showed promising results as the fatigue life was improved from that of the grind-out substrate. © 2014, Elsevier B.V.
- ItemEffect of residual stress on the integrity of a branch connection(Elsevier Science Ltd, 2012-08-01) Law, M; Kirstein, O; Luzin, VA new connection to an existing gas pipeline was made by hot-tapping, welding directly onto a pressurised pipeline. The welds were not post-weld heat treated, causing significant residual stresses. The critical weld had residual stresses determined by neutron diffraction using ANSTO's residual stress diffractometer, Kowari. The maximum measured residual stress (290 MPa) was 60% of the yield strength. The magnitudes of errors from a number of sources were estimated. An integrity assessment of the welded branch connection was performed with the measured residual stress values and with residual stress distributions from the BS 7910 and API 579 analysis codes. Analysis using estimates of residual stress from API 579 overestimated the critical crack size. © 2012, Elsevier Ltd.
- ItemEffect of scan rotation on the microstructure development and mechanical properties of 316L parts produced by laser powder bed fusion(Elsevier B.V., 2020-05) Leicht, A; Yu, CH; Luzin, V; Klement, U; Hryha, EMAdditive manufacturing possesses appealing features for producing high-performance components, for a wide range of materials. One of these features is the ability to locally tailor the microstructure and in turn, the mechanical properties. This study investigates how the microstructure of stainless steel 316L parts produced by laser powder bed fusion are affected by alternating the laser scan orientation. The microstructure consists of large elongated grains with a fine cell substructure. This study established the correlation between the orientation of this substructure and the crystallographic orientation. The results show that by producing parts without any rotation a quite unique crystallographic orientation can be achieved. The grain structure primarily consisted of large 〈101〉 oriented grains, that were separated by thin bands of small 〈100〉 oriented grains with respect to the building direction. As rotation was added these bands were eliminated. Samples that were produced without any rotation generated the highest tensile strength (527 ± 5.4 MPa), yield strength (449 ± 2.4 MPa) and ductility (58 ± 1.3%). The lowest mechanical properties were obtained for samples that were produced using a scan rotation of 67° with the tensile strength of 485 ± 4.8 MPa, yield strength of 427 ± 5.4 MPa and ductility of 50 ± 1.3%. This indicates that cell orientation and crystallographic orientation plays an essential role in the tensile properties of 316L parts produced by laser powder bed fusion (L-PBF). © 2020 Elsevier Inc.
- ItemEffect of spatial variation of stress-free lattice spacings on measured residual stresses(SAGE Publications, 2011-11-01) Law, M; Luzin, VWhen neutron diffraction is used to measure residual stresses, estimates of the unstressed lattice spacing (d(0)) are often required. These are generally measured on a sample that is considered representative of the component. In the case of welded samples, the possibility of variation in weld shape between the d(0) sample and the area where stresses are determined must be taken into account. To assess this, d(0) values are measured on an area considered representative of the sample, and then are re-measured on a sample cut from the actual strain measurement plane. The residual stresses are re-calculated with these new d(0) values and the results compared to those based on the initial d(0) measurement. Methods of estimating these errors are discussed. The errors in residual stress that arise from the spatial variation of d(0) values are greater than the commonly reported peak fitting errors. These errors can be estimated and should be included in the reported residual stress measurements. Cutting a d(0) sample from the measurement plane makes this a destructive technique. © 2011, SAGE Publications
- ItemThe effect of the crystallographic texture on intergranular stress corrosion crack paths(Elsevier, 2014-11) Lavigne, O; Gamboa, E; Luzin, V; Law, M; Giuliani, M; Costin, WIntergranular stress corrosion cracking (IGSCC) crack paths usually travel perpendicular to the applied load direction. Some instances of crack paths propagating in directions away from the perpendicular have been observed in low carbon steels. This study shows that the crystallographic texture is a critical factor that drives the IGSCC crack path. Residual shear strain induced by shear texture (induced by rolling processes) explains the inclination of the cracks at a certain depth and the continuous propagation of the cracks along the transverse directions. The residual strains coming from the manufacturing processes determine the crack propagation paths. © 2014, Elsevier B.V.
- ItemEffects of cutting and specimen size on neutron measurement of residual stresses(Insitute of Physics, 2010-12-16) Law, M; Luzin, V; Kirstein, OTo perform neutron residual stress measurements it is often necessary to cut samples to a manageable size. The effects of cutting a girth welded pipe were investigated with analytical methods and finite element analysis. The effect of cutting on measured stresses was calculated. A simplified method of modelling residual stresses in welds, "chill modelling", is introduced. In ring slitting a cut is made in the axial direction and the deformation is maeesured. The change in elastic stress can be calculated and added to neutron diffraction measurements made on a cut ring to calculate the original stresses. Residual stress measurements were performed to validate the ring slitting correction using ANSTO's residual stress diffractometer Kowari. © 2010, Insitute of Physics.