ABSTRACT In this study two types of laser surface treatment, laser surface melting and laser proc... more ABSTRACT In this study two types of laser surface treatment, laser surface melting and laser processing, were used to treat the surface of as cast Nickel–Aluminium Bronze. The two treatments were then subjected to cavitation erosion testing and were compared against as-cast Nickel–Aluminium Bronze. While the cavitation performance of the two types of laser surface treatment was equivalent, the morphology of the eroded surfaces was different. Several materials characterisation techniques including neutron diffraction for residual stress measurements and SEM were used to explain why the two eroded surfaces were different. It was found that the tensile residual stresses in the laser melted sample weakened the sample, which negated its superior strength when compared with the laser processed sample. It was also observed that the erosion and pitting in the laser melted sample were deeper and they were attributed to the tensile residual stresses accelerating the attack at grain boundaries.
The metal finishing process of electrolytic hard chrome (EHC) plating has been identified as a so... more The metal finishing process of electrolytic hard chrome (EHC) plating has been identified as a source of environmental pollution in most industrialized countries like Australia, Europe and USA. The key driver for the technology replacement is that the EHC plating process uses hexavalent chromium, which is a known carcinogen. Our previous research has identified that cold spray nanostructured tungsten carbide cobalt (WC-Co) coatings can be a suitable alternative to provide a functional coating in wear applications. This work explores at another similar technology- Kinetic Metallization for deposition of WC-Co coatings. In this work, the objective is to characterize the residual stress profile of these WC-Co coatings that are deposited by the latest KM systems. These coating systems are used in critical applications such as landing gear pistons and axle journals, hydraulic rods, engine shaft journals, and numerous other external surfaces that operate under high cyclic loading conditions. As such, the residual stress developed during the KM coating process has a significant influence on the fatigue properties of the components. Thus, knowledge of stresses and their linkage with other properties and production parameters is essential for the quality control of these critical structures.
The mechanical integrity of WC-Co coatings is critical for their performance in wear, corrosion, ... more The mechanical integrity of WC-Co coatings is critical for their performance in wear, corrosion, and impact resistance applications. Residual stress, with its role in development of cracking, micro-cracking, and delamination, is another integral part of the mechanical characterization of the coated systems. In the given study, the residual stress of the WC-Co coatings on steel and stainless steel substrates was examined in two conditions, after deposition and after subsequent surface grinding. Several experimental techniques, including bi-layer curvature, X-ray diffraction, and neutron diffraction, were used to assess residual stress in the coatings and to enable comparison between the methods. Residual stresses induced by deposition are mostly due to rapid particle quenching and solidification upon impact, as well as any cold working induced by high velocity particle impact, but for the WC ceramic particles both effects are insignificant and result in small deposition stress. Thermal mismatch between materials of coating and substrate is the major source of stress and scale accordingly to the CTE of the substrate and coating materials and deposition temperature. It was demonstrated that the grinding applied to surface does not modify the as-sprayed residual stresses in the coatings significantly therefore assuming absence of microcracking that could have potentially affect the residual stresses.
A synergic combination of neutron techniques was applied to characterize non-invasively the lamin... more A synergic combination of neutron techniques was applied to characterize non-invasively the laminated structure of a set of ancient katana, part of the East Asian Collection of the Museum of Applied Arts and Sciences (MAAS) in Sydney. Neutron tomography, diffraction, residual stress and Bragg-edge transmission analyses were undertaken on samples of well-known origin, time period and authorship to create a reference database on the main manufacturing methods developed by Japanese swordsmiths. In the attempt to attribute mumei (no-signature) blades basing on a scientific analytical method rather than a stylistic analysis, data from the reference samples were benchmarked against the results obtained from the unknown blade to identify differences and commonalities in the production process.
ABSTRACT The numerical application of solid-state phase transformation kinetics relating to conve... more ABSTRACT The numerical application of solid-state phase transformation kinetics relating to conventional welding of ferritic steels is presented. The inclusion of such kinetics in weld models is shown to be necessary for capturing the post-weld residual stress field. To this end, a comparison of two approaches is outlined: a semi-empirical approach that uses thermodynamic transformation kinetics to predict phase morphology; and a fully empirical approach that directly links local material temperature to the present constituent phase(s). The semi-empirical analysis begins with prediction of TTT diagrams using thermodynamic principles for ferritic steels. The data is then converted to CCT diagrams using the Scheil-Avrami additive rule, including austenite grain growth kinetics. This information is used to predict the phases present under varying peak temperatures and cooling rates. In the fully empirical approach, dilatometric experiments of steel samples are performed during heating to simulate expected welding conditions. The constitutive response of the sample is then used as input for the subsequent numerical weld analyses. Input derived from each technique is transferred into weld models developed using the Abaqus finite element package. Model validation is carried out by direct comparison with neutron diffraction residual stress measurements on two beams of SA508 Gr.3 Cl.1 steel subjected to autogenous beam TIG welds under varying torch speeds, heat input and preheat conditions.
HRTex is a new texture data processing tool for two-dimensional position-sensitive area detectors... more HRTex is a new texture data processing tool for two-dimensional position-sensitive area detectors on monochromatic neutron diffractometers. With the aim of improving the resolution and accuracy of pole figure calculations, HRTex treats the raw data of the area detector for each pixel and projects the intensity of each pixel directly onto a high-resolution pole figure. With the resultant refinement of the resolution, HRTex can distinguish close texture peaks with a flexible resolution setting and reduced information loss. Test results of HRTex on the data sets of two samples measured by two different neutron facilities are analysed, and the improvements in accuracy, resolution and efficiency of the pole figure calculation are discussed.
International Thermal Spray Conference and Exposition (ITSC), May 11, 2015
The mechanical integrity of WC-Co coatings is critical for their performance in wear, corrosion, ... more The mechanical integrity of WC-Co coatings is critical for their performance in wear, corrosion, and impact resistance applications. Residual stress, with its role in development of cracking, micro-cracking, and delamination, is another integral part of the mechanical characterization of the coated systems. In the given study, the residual stress of the WC-Co coatings on steel and stainless steel substrates was examined in two conditions, after deposition and after subsequent surface grinding. Several experimental techniques, including bi-layer curvature, X-ray diffraction, and neutron diffraction, were used to assess residual stress in the coatings and to enable comparison between the methods. Residual stresses induced by deposition are mostly due to rapid particle quenching and solidification upon impact, as well as any cold working induced by high velocity particle impact, but for the WC ceramic particles both effects are insignificant and result in small deposition stress. Thermal mismatch between materials of coating and substrate is the major source of stress and scale accordingly to the CTE of the substrate and coating materials and deposition temperature. It was demonstrated that the grinding applied to surface does not modify the as-sprayed residual stresses in the coatings significantly therefore assuming absence of microcracking that could have potentially affect the residual stresses.
Marcellus Shale samples were used to quantify mineralogy and texture, evaluate the abundance and ... more Marcellus Shale samples were used to quantify mineralogy and texture, evaluate the abundance and thermal maturity of organic matter, describe porosity and interpret the diagenetic history of this post‐mature shale‐gas reservoir. A multidisciplinary approach was adopted comprising X-ray diffraction to quantify the mineralogy, neutron diffraction to quantify the texture of the rock-forming minerals, electron microscopy to visualise porosity in the shale and distinguish between detrital and diagenetic phases and Raman spectroscopy to quantify thermal transformation in the organic matter. Results indicate that the samples are composed of quartz, illite, calcite, chlorite, albite, and pyrite with a total organic content ranging between 3 and 7 wt %. There is a significant crystallographic preferred orientation in the diagenetic illite and calcite that can be well modelled assuming transverse isotropy; quartz shows random texture. Nano sized pores are observed within the organic matter as well as at mineral junctions. Raman geothermometry indicate that the sediment witnessed maximum temperatures of approximately 250°C commensurate with the high optical reflectance (R0 > 4.5%) reported on the same material. This and the analysis of illite cristallinity indicate that the Marcellus Shale has been exposed to prehnite-pumpellyite metamorphic facies and a maximum burial depth of 6-8 km
ABSTRACT In this study two types of laser surface treatment, laser surface melting and laser proc... more ABSTRACT In this study two types of laser surface treatment, laser surface melting and laser processing, were used to treat the surface of as cast Nickel–Aluminium Bronze. The two treatments were then subjected to cavitation erosion testing and were compared against as-cast Nickel–Aluminium Bronze. While the cavitation performance of the two types of laser surface treatment was equivalent, the morphology of the eroded surfaces was different. Several materials characterisation techniques including neutron diffraction for residual stress measurements and SEM were used to explain why the two eroded surfaces were different. It was found that the tensile residual stresses in the laser melted sample weakened the sample, which negated its superior strength when compared with the laser processed sample. It was also observed that the erosion and pitting in the laser melted sample were deeper and they were attributed to the tensile residual stresses accelerating the attack at grain boundaries.
The metal finishing process of electrolytic hard chrome (EHC) plating has been identified as a so... more The metal finishing process of electrolytic hard chrome (EHC) plating has been identified as a source of environmental pollution in most industrialized countries like Australia, Europe and USA. The key driver for the technology replacement is that the EHC plating process uses hexavalent chromium, which is a known carcinogen. Our previous research has identified that cold spray nanostructured tungsten carbide cobalt (WC-Co) coatings can be a suitable alternative to provide a functional coating in wear applications. This work explores at another similar technology- Kinetic Metallization for deposition of WC-Co coatings. In this work, the objective is to characterize the residual stress profile of these WC-Co coatings that are deposited by the latest KM systems. These coating systems are used in critical applications such as landing gear pistons and axle journals, hydraulic rods, engine shaft journals, and numerous other external surfaces that operate under high cyclic loading conditions. As such, the residual stress developed during the KM coating process has a significant influence on the fatigue properties of the components. Thus, knowledge of stresses and their linkage with other properties and production parameters is essential for the quality control of these critical structures.
The mechanical integrity of WC-Co coatings is critical for their performance in wear, corrosion, ... more The mechanical integrity of WC-Co coatings is critical for their performance in wear, corrosion, and impact resistance applications. Residual stress, with its role in development of cracking, micro-cracking, and delamination, is another integral part of the mechanical characterization of the coated systems. In the given study, the residual stress of the WC-Co coatings on steel and stainless steel substrates was examined in two conditions, after deposition and after subsequent surface grinding. Several experimental techniques, including bi-layer curvature, X-ray diffraction, and neutron diffraction, were used to assess residual stress in the coatings and to enable comparison between the methods. Residual stresses induced by deposition are mostly due to rapid particle quenching and solidification upon impact, as well as any cold working induced by high velocity particle impact, but for the WC ceramic particles both effects are insignificant and result in small deposition stress. Thermal mismatch between materials of coating and substrate is the major source of stress and scale accordingly to the CTE of the substrate and coating materials and deposition temperature. It was demonstrated that the grinding applied to surface does not modify the as-sprayed residual stresses in the coatings significantly therefore assuming absence of microcracking that could have potentially affect the residual stresses.
A synergic combination of neutron techniques was applied to characterize non-invasively the lamin... more A synergic combination of neutron techniques was applied to characterize non-invasively the laminated structure of a set of ancient katana, part of the East Asian Collection of the Museum of Applied Arts and Sciences (MAAS) in Sydney. Neutron tomography, diffraction, residual stress and Bragg-edge transmission analyses were undertaken on samples of well-known origin, time period and authorship to create a reference database on the main manufacturing methods developed by Japanese swordsmiths. In the attempt to attribute mumei (no-signature) blades basing on a scientific analytical method rather than a stylistic analysis, data from the reference samples were benchmarked against the results obtained from the unknown blade to identify differences and commonalities in the production process.
ABSTRACT The numerical application of solid-state phase transformation kinetics relating to conve... more ABSTRACT The numerical application of solid-state phase transformation kinetics relating to conventional welding of ferritic steels is presented. The inclusion of such kinetics in weld models is shown to be necessary for capturing the post-weld residual stress field. To this end, a comparison of two approaches is outlined: a semi-empirical approach that uses thermodynamic transformation kinetics to predict phase morphology; and a fully empirical approach that directly links local material temperature to the present constituent phase(s). The semi-empirical analysis begins with prediction of TTT diagrams using thermodynamic principles for ferritic steels. The data is then converted to CCT diagrams using the Scheil-Avrami additive rule, including austenite grain growth kinetics. This information is used to predict the phases present under varying peak temperatures and cooling rates. In the fully empirical approach, dilatometric experiments of steel samples are performed during heating to simulate expected welding conditions. The constitutive response of the sample is then used as input for the subsequent numerical weld analyses. Input derived from each technique is transferred into weld models developed using the Abaqus finite element package. Model validation is carried out by direct comparison with neutron diffraction residual stress measurements on two beams of SA508 Gr.3 Cl.1 steel subjected to autogenous beam TIG welds under varying torch speeds, heat input and preheat conditions.
HRTex is a new texture data processing tool for two-dimensional position-sensitive area detectors... more HRTex is a new texture data processing tool for two-dimensional position-sensitive area detectors on monochromatic neutron diffractometers. With the aim of improving the resolution and accuracy of pole figure calculations, HRTex treats the raw data of the area detector for each pixel and projects the intensity of each pixel directly onto a high-resolution pole figure. With the resultant refinement of the resolution, HRTex can distinguish close texture peaks with a flexible resolution setting and reduced information loss. Test results of HRTex on the data sets of two samples measured by two different neutron facilities are analysed, and the improvements in accuracy, resolution and efficiency of the pole figure calculation are discussed.
International Thermal Spray Conference and Exposition (ITSC), May 11, 2015
The mechanical integrity of WC-Co coatings is critical for their performance in wear, corrosion, ... more The mechanical integrity of WC-Co coatings is critical for their performance in wear, corrosion, and impact resistance applications. Residual stress, with its role in development of cracking, micro-cracking, and delamination, is another integral part of the mechanical characterization of the coated systems. In the given study, the residual stress of the WC-Co coatings on steel and stainless steel substrates was examined in two conditions, after deposition and after subsequent surface grinding. Several experimental techniques, including bi-layer curvature, X-ray diffraction, and neutron diffraction, were used to assess residual stress in the coatings and to enable comparison between the methods. Residual stresses induced by deposition are mostly due to rapid particle quenching and solidification upon impact, as well as any cold working induced by high velocity particle impact, but for the WC ceramic particles both effects are insignificant and result in small deposition stress. Thermal mismatch between materials of coating and substrate is the major source of stress and scale accordingly to the CTE of the substrate and coating materials and deposition temperature. It was demonstrated that the grinding applied to surface does not modify the as-sprayed residual stresses in the coatings significantly therefore assuming absence of microcracking that could have potentially affect the residual stresses.
Marcellus Shale samples were used to quantify mineralogy and texture, evaluate the abundance and ... more Marcellus Shale samples were used to quantify mineralogy and texture, evaluate the abundance and thermal maturity of organic matter, describe porosity and interpret the diagenetic history of this post‐mature shale‐gas reservoir. A multidisciplinary approach was adopted comprising X-ray diffraction to quantify the mineralogy, neutron diffraction to quantify the texture of the rock-forming minerals, electron microscopy to visualise porosity in the shale and distinguish between detrital and diagenetic phases and Raman spectroscopy to quantify thermal transformation in the organic matter. Results indicate that the samples are composed of quartz, illite, calcite, chlorite, albite, and pyrite with a total organic content ranging between 3 and 7 wt %. There is a significant crystallographic preferred orientation in the diagenetic illite and calcite that can be well modelled assuming transverse isotropy; quartz shows random texture. Nano sized pores are observed within the organic matter as well as at mineral junctions. Raman geothermometry indicate that the sediment witnessed maximum temperatures of approximately 250°C commensurate with the high optical reflectance (R0 > 4.5%) reported on the same material. This and the analysis of illite cristallinity indicate that the Marcellus Shale has been exposed to prehnite-pumpellyite metamorphic facies and a maximum burial depth of 6-8 km
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