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Roger Lewis - One of the best experts on this subject based on the ideXlab platform.
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Assessing the impact of small amounts of water and iron oxides on adhesion in the wheel/rail interface using High Pressure Torsion Testing
Tribology International, 2019Co-Authors: L.e. Buckley-johnstone, Petr Voltr, Gerald Trummer, David I. Fletcher, Alexander Meierhofer, Roger LewisAbstract:Abstract A new High Pressure Torsion (HPT) set-up has been developed for assessing the effect of third body materials in the wheel/rail interface in a representative and controlled manner. In this study the technique has been used to investigate the effect of small amounts of water and iron oxides mixtures when subjected to different contact pressures. HPT tests showed reduction in adhesion relative to a dry contact when Testing with small amounts of water and/or oxides, however sustained low adhesion (μ
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assessing the impact of small amounts of water and iron oxides on adhesion in the wheel rail interface using high pressure Torsion Testing
Tribology International, 2019Co-Authors: L E Buckleyjohnstone, Petr Voltr, Gerald Trummer, David I. Fletcher, Alexander Meierhofer, Roger LewisAbstract:Abstract A new High Pressure Torsion (HPT) set-up has been developed for assessing the effect of third body materials in the wheel/rail interface in a representative and controlled manner. In this study the technique has been used to investigate the effect of small amounts of water and iron oxides mixtures when subjected to different contact pressures. HPT tests showed reduction in adhesion relative to a dry contact when Testing with small amounts of water and/or oxides, however sustained low adhesion (μ
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assessing the impact of small amounts of water and iron oxides on adhesion in the wheel rail interface using high pressure Torsion Testing
Tribology International, 2019Co-Authors: L E Buckleyjohnstone, Petr Voltr, Gerald Trummer, David I. Fletcher, Alexander Meierhofer, Klaus Six, Roger LewisAbstract:A new High Pressure Torsion (HPT) set-up has been developed for assessing the effect of third body materials in the wheel/rail interface in a representative and controlled manner. In this study the technique has been used to investigate the effect of small amounts of water and iron oxides mixtures when subjected to different contact pressures. HPT tests showed reduction in adhesion relative to a dry contact when Testing with small amounts of water and/or oxides, however sustained low adhesion (μ<0.05) was not produced. To aid interpretation of the results a model has been developed to explore the behavior encountered when Testing with water and iron oxide mixtures. The model relates the shear properties of water and oxide mixtures (with increasing solid content) to a predicted adhesion. The model shows a narrow window of water to oxide fraction is required for reduced adhesion, particularly on rough surfaces, and this correlates with the behavior observed.
L E Buckleyjohnstone - One of the best experts on this subject based on the ideXlab platform.
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assessing the impact of small amounts of water and iron oxides on adhesion in the wheel rail interface using high pressure Torsion Testing
Tribology International, 2019Co-Authors: L E Buckleyjohnstone, Petr Voltr, Gerald Trummer, David I. Fletcher, Alexander Meierhofer, Roger LewisAbstract:Abstract A new High Pressure Torsion (HPT) set-up has been developed for assessing the effect of third body materials in the wheel/rail interface in a representative and controlled manner. In this study the technique has been used to investigate the effect of small amounts of water and iron oxides mixtures when subjected to different contact pressures. HPT tests showed reduction in adhesion relative to a dry contact when Testing with small amounts of water and/or oxides, however sustained low adhesion (μ
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assessing the impact of small amounts of water and iron oxides on adhesion in the wheel rail interface using high pressure Torsion Testing
Tribology International, 2019Co-Authors: L E Buckleyjohnstone, Petr Voltr, Gerald Trummer, David I. Fletcher, Alexander Meierhofer, Klaus Six, Roger LewisAbstract:A new High Pressure Torsion (HPT) set-up has been developed for assessing the effect of third body materials in the wheel/rail interface in a representative and controlled manner. In this study the technique has been used to investigate the effect of small amounts of water and iron oxides mixtures when subjected to different contact pressures. HPT tests showed reduction in adhesion relative to a dry contact when Testing with small amounts of water and/or oxides, however sustained low adhesion (μ<0.05) was not produced. To aid interpretation of the results a model has been developed to explore the behavior encountered when Testing with water and iron oxide mixtures. The model relates the shear properties of water and oxide mixtures (with increasing solid content) to a predicted adhesion. The model shows a narrow window of water to oxide fraction is required for reduced adhesion, particularly on rough surfaces, and this correlates with the behavior observed.
Fei Zhang - One of the best experts on this subject based on the ideXlab platform.
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slow crack growth resistance of electrically conductive zirconia based composites with non oxide reinforcements
Journal of The European Ceramic Society, 2019Co-Authors: Jerome Chevalier, C Olagnon, Fei Zhang, Shuigen Huang, Wout Veulemans, Kim Vanmeensel, Jef VleugelsAbstract:Abstract Slow crack growth (SCG) behavior of four zirconia-based composites reinforced with 40 vol% WC, TiC, NbC or TiCN were studied by means of double-Torsion Testing. Compared to monolithic zirconia, the composites had a higher resistance to fast fracture, i.e., higher fracture toughness. The extent of toughening depended on the reinforcement type, shifting the V-KI (crack velocity versus stress intensity factor) curve parallel to higher KI values. More importantly, these composites were less sensitive to SCG. Identical V-KI/KIC curves with steeper slopes compared to monolithic zirconia were observed for the investigated composites, independent on the reinforcement type. No rising R-curve was measured, at least in the crack-size domain investigated by SCG. Therefore, the higher SCG resistance of the composites was due to the intrinsic stress-assisted corrosion resistance of the covalent non-oxide secondary phase.
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Slow crack growth resistance of electrically conductive zirconia-based composites with non-oxide reinforcements
Journal of the European Ceramic Society, 2019Co-Authors: Fei Zhang, C Olagnon, Shuigen Huang, Wout Veulemans, Kim Vanmeensel, J. Chevalier, Jef VleugelsAbstract:Slow crack growth (SCG) behavior of four zirconia-based composites reinforced with 40 vol% WC, TiC, NbC or TiCN were studied by means of double-Torsion Testing. Compared to monolithic zirconia, the composites had a higher resistance to fast fracture, i.e., higher fracture toughness. The extent of toughening depended on the reinforcement type, shifting the V-KI (crack velocity versus stress intensity factor) curve parallel to higher KI values. More importantly, these composites were less sensitive to SCG. Identical V-KI/KIC curves with steeper slopes compared to monolithic zirconia were observed for the investigated composites, independent on the reinforcement type. No rising R-curve was measured, at least in the crack-size domain investigated by SCG. Therefore, the higher SCG resistance of the composites was due to the intrinsic stress-assisted corrosion resistance of the covalent non-oxide secondary phase. © 2018 Elsevier Ltd
Jef Vleugels - One of the best experts on this subject based on the ideXlab platform.
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slow crack growth resistance of electrically conductive zirconia based composites with non oxide reinforcements
Journal of The European Ceramic Society, 2019Co-Authors: Jerome Chevalier, C Olagnon, Fei Zhang, Shuigen Huang, Wout Veulemans, Kim Vanmeensel, Jef VleugelsAbstract:Abstract Slow crack growth (SCG) behavior of four zirconia-based composites reinforced with 40 vol% WC, TiC, NbC or TiCN were studied by means of double-Torsion Testing. Compared to monolithic zirconia, the composites had a higher resistance to fast fracture, i.e., higher fracture toughness. The extent of toughening depended on the reinforcement type, shifting the V-KI (crack velocity versus stress intensity factor) curve parallel to higher KI values. More importantly, these composites were less sensitive to SCG. Identical V-KI/KIC curves with steeper slopes compared to monolithic zirconia were observed for the investigated composites, independent on the reinforcement type. No rising R-curve was measured, at least in the crack-size domain investigated by SCG. Therefore, the higher SCG resistance of the composites was due to the intrinsic stress-assisted corrosion resistance of the covalent non-oxide secondary phase.
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Slow crack growth resistance of electrically conductive zirconia-based composites with non-oxide reinforcements
Journal of the European Ceramic Society, 2019Co-Authors: Fei Zhang, C Olagnon, Shuigen Huang, Wout Veulemans, Kim Vanmeensel, J. Chevalier, Jef VleugelsAbstract:Slow crack growth (SCG) behavior of four zirconia-based composites reinforced with 40 vol% WC, TiC, NbC or TiCN were studied by means of double-Torsion Testing. Compared to monolithic zirconia, the composites had a higher resistance to fast fracture, i.e., higher fracture toughness. The extent of toughening depended on the reinforcement type, shifting the V-KI (crack velocity versus stress intensity factor) curve parallel to higher KI values. More importantly, these composites were less sensitive to SCG. Identical V-KI/KIC curves with steeper slopes compared to monolithic zirconia were observed for the investigated composites, independent on the reinforcement type. No rising R-curve was measured, at least in the crack-size domain investigated by SCG. Therefore, the higher SCG resistance of the composites was due to the intrinsic stress-assisted corrosion resistance of the covalent non-oxide secondary phase. © 2018 Elsevier Ltd
Peter Hodgson - One of the best experts on this subject based on the ideXlab platform.
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characterization on ferrite microstructure evolution during large strain warm Torsion Testing of plain low carbon steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: B Eghbali, Hossein Beladi, A Abdollahzadeh, Peter HodgsonAbstract:Ferrite grain/subgrain structures evolution during the extended dynamic softening of a plain low carbon steel was investigated throughout the large strain warm deformation by hot Torsion. Microstructural analysis with electron back-scattering diffraction (EBSD) scanning electron microscope (FEG/SEM) was carried out on the ferrite microstructural parameters. The results showed that the warm flow stress–strain curves are similar to those affected only by dynamic softening and an extended warm flow softening is seen during large strain deformation up to 30. Furthermore, with an increase in strain up to ~ vert, similar1 the grain size of ferrite, misorientation angle and fraction of high-angle boundaries gradually decrease and fraction of low-angle boundaries increases. With a further increase in the strain beyond ~, vert, similar2, these parameters remain approximately unchanged. No evidence of discontinuous dynamic recrystallisation involving nucleation and growth of new grains was found within ferrite. Therefore, the dynamic softening mechanism observed during large strain ferritic deformation is explained by continuous dynamic recrystallization (CDRX).
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effect of thermomechanical parameters on the critical strain for ultrafine ferrite formation through hot Torsion Testing
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: Hossein Beladi, Alireza Shokouhi, Georgina Kelly, Peter HodgsonAbstract:Abstract A C–Mn–V steel was used to study ultrafine ferrite formation (1–3 μm) through dynamic strain-induced transformation (DSIT) using hot Torsion experiments. A systematic study determined the critical strain for the start of DSIT (eC,DSIT), although this may not lead to a fully ultrafine microstructure. Therefore, the strain to produce an ultrafine ferrite (UFF) as final microstructure (eC,UFF) during deformation was also determined. In addition, the effect of thermomechanical parameters such as deformation temperature, prior austenite grain size, strain rate and cooling rate on eC,DSIT and eC,UFF has been evaluated. DSIT ferrite nucleated on prior austenite grain boundaries at an early stage of straining followed by intragranular nucleation at higher strains. The prior austenite grain size affected the distribution of DSIT ferrite nucleation sites at an early stage of transformation and the subsequent coarsening behaviour of the grain boundary and intragranular ferrite grains during post-deformation cooling. Also, eC,DSIT and eC,UFF increased with an increase in the prior austenite grain size and deformation temperature. The post-deformation cooling had a strong effect not only on eC,UFF but also the UFF microstructure (i.e. final ferrite grain size and second phase characteristics).
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the production of ultrafine ferrite during hot Torsion Testing of a 0 11 wt pct c steel
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2002Co-Authors: P J Hurley, Barrington Charles Muddle, Peter HodgsonAbstract:Ultrafine ferrite grain sizes were produced in a 0.11C-1.6Mn-0.2Si steel by Torsion Testing isothermally at 675 °C after air cooling from 1250 °C. The ferrite was observed to form intragranularly beyond a von Mises equivalent tensile strain of approximately 0.7 to 0.8 and the number fraction of intragranular ferrite grains continued to increase as the strain level increased. Ferrite nucleated to form parallel and closely spaced linear arrays or “rafts” of many discrete ultrafine ferrite grains. It is shown that ferrite nucleates during deformation on defects developed within the austenite parallel to the macroscopic shear direction (i.e., dynamic strain-induced transformation). A model austenitic Ni-30Fe alloy was used to study the substructure developed in the austenite under similar test conditions as that used to induce intragranular ferrite in the steel. It is shown that the most prevalent features developed during Testing are microbands. It is proposed that high-energy jogged regions surrounding intersecting microbands provide potential sites for ferrite nucleation at lower strains, while at higher strains, the walls of the microbands may also act as nucleation sites.
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effect of process variables on formation of dynamic strain induced ultrafine ferrite during hot Torsion Testing
Materials Science and Technology, 2001Co-Authors: Peter Hurley, Peter HodgsonAbstract:AbstractUltrafine grain sizes were produced using hot Torsion Testing of a 0.11C-1.68Mn-0.20Si wt- steel, with ultrafine ferrite <1 m nucleating intragranularly during Testing by dynamic strain induced transformation. A systematic study was made of the effect of isothermal deformation temperature, strain level, strain rate, and accelerated cooling during deformation on the formation of ultrafine ferrite by this process. Decreasing the isothermal Testing temperature below the Ae3 temperature led to a greater driving force for ferrite nucleation and thus more extensive nucleation during Testing; the formation of Widmanstatten ferrite prior to, or early during, deformation imposed a lower temperature limit. Increasing the strain above that where ferrite first began 0.8 at 675C and a strain rate of 3 s1 increased the intragranular nucleation of ferrite. Strain rate appeared to have little effect on the amount of ferrite formed. However, slower strain rates led to extensive polygonisation of the ferrite formed...