The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Filippo Berto - One of the best experts on this subject based on the ideXlab platform.
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High Temperature Fatigue Behaviour of Secondary AlSi7Cu3Mg Alloys
Structural Integrity, 2019Co-Authors: Alessandro De Mori, Giulio Timelli, Filippo BertoAbstract:The high temperature Fatigue behaviour of secondary AlSi7Cu3Mg alloys has been investigated. The alloy has been solubilized and aged for different times to obtain the age-hardening profile. The peak hardness is reached at 180 °C after 4 h ageing treatment. Further, the hardness stabilizes showing a plateau in the range between 5 and 10 hours of ageing treatment. The heat treatment leads to a complete dissolution of Cu-rich phases, spheroidization of eutectic Si particles and precipitation inside the α-Al matrix. Several Fatigue tests have been carried out on selected heat-treated specimens both at room and elevated temperatures (200 and 300 °C). The obtained results show how the Fatigue strength decreases with increasing the testing temperature.
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advanced materials for applications at high temperature Fatigue assessment by means of local strain energy density
Advanced Engineering Materials, 2016Co-Authors: Pasquale Gallo, Filippo BertoAbstract:The interest on Fatigue assessment of steel and other alloys at high temperature has increased continuously in the last years. However, high cycle Fatigue of notched components at high temperature has not been deeply investigated experimentally and theoretically. The present paper investigates the accuracy of Strain Energy Density (SED) averaged over a control volume approach when applied to High-Temperature Fatigue data from notched components. In the present work, a large bulk of High-Temperature Fatigue data, taken from the literature and regarding notched components made of different advanced materials, is reanalyzed. In detail: C45 carbon steel at 250 °C, Inconel 718 at 500 °C, and directionally solidified superalloy DZ125 at 850 °C are considered. The main advantage of SED averaged over a control volume is that different geometries can be summarized in a single narrow scatter band. From an industrial viewpoint, the use of a geometry-independent parameter (and Fatigue curve) leads to a considerable advantage in terms of time and cost.
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High temperature Fatigue tests and crack growth in 40CrMoV13.9 notched components
Frattura ed Integrità Strutturale, 2015Co-Authors: Pasquale Gallo, Filippo BertoAbstract:The present paper addresses experimentally the high temperature Fatigue of 40CrMoV13.9 steel and the effect of surface roughness on Fatigue strength and crack initiation. The 40CrMoV13.9 steel is widely used in different engineering high temperature applications among which hot- rolling of metals, where, in order to assure a constant temperature, the rolls are provided with cooling channels. These are the most stressed zone of the rolls where cracks systematically initiate. In order to completely characterize the high temperature behaviour of this steel, firstly uniaxial-tension load controlled Fatigue tests have been conducted at different temperatures up to 650°C. Two geometries are considered: plain specimens and plates weakened by symmetric V-notches. Subsequently, with the aim to investigate the influence of the cooling channels roughness on the high temperature behaviour and the cracks initiation, uniaxial-tension load controlled Fatigue tests have been conducted on plate with central hole at the service temperature of 650°C varying the surface roughness. After a brief review of the recent literature, the experimental procedure is described in detail and the new data from un-notched and notched specimens are summarized in terms of stress range, at the considered temperatures. Finally, Fatigue data from un-notched and notched specimens are re-analysed by means of the mean value of the Strain Energy Density (SED) approach extended at high temperature.
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extension of linear elastic strain energy density approach to high temperature Fatigue and a synthesis of cu be alloy experimental tests
Engineering Solid Mechanics, 2015Co-Authors: Filippo Berto, Pasquale GalloAbstract:Article history: Received October 6, 2014 Accepted 28 January 2015 Available online 29 January 2015 The present paper summarizes the results from uniaxial-tension stress-controlled Fatigue tests performed at different temperatures up to 650°C on Cu-Be specimens. Two geometries are considered: hourglass shaped and plates weakened by a central hole (Cu-Be alloy). The motivation of the present work is that, at the best of authors’ knowledge, only a limited number of papers on these alloys under High-Temperature Fatigue are available in the literature and no results deal with notched components. The Cu-Be specimens Fatigue data are re-analyzed in terms of the mean value of the Strain Energy Density (SED) averaged over a control volume. Thanks to the SED approach it is possible to summarize in a single scatter-band all the Fatigue data, independently of the specimen geometry. © 2015 Growing Science Ltd. All rights reserved.
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Influence of surface roughness on high temperature Fatigue strength and cracks initiation in 40CrMoV13.9 notched components
Theoretical and Applied Fracture Mechanics, 2015Co-Authors: Pasquale Gallo, Filippo BertoAbstract:Abstract The present paper addresses experimentally the high temperature Fatigue of 40CrMoV13.9 steel and the effect of surface roughness on Fatigue strength and cracks initiation. The 40CrMoV13.9 steel considered here is widely used in different engineering high temperature applications among which hot-rolling of metals, where, in order to assure a constant temperature, the rolls are provided with cooling channels. These are the most stressed zone of the rolls where cracks initiate systematically. In order to completely characterize the high temperature behaviour of this steel, firstly uniaxial-tension load controlled Fatigue tests have been conducted at different temperatures up to 650 °C. Two geometries are considered: plain specimens and plates weakened by symmetric V-notches, with opening angle and tip radius being equal to 90° and 1 mm, respectively. Subsequently, with the aim to investigate the influence of the cooling channels roughness on the high temperature behaviour and the cracks initiation, uniaxial-tension load controlled Fatigue tests have been conducted on plate with central hole at the service temperature of 650 °C, varying the surface roughness. After a brief review of the recent literature, the experimental procedure is described in detail and the new data from un-notched and notched specimens are summarized in terms of stress range, at the considered temperatures. Finally, Fatigue data from un-notched and notched specimens are re-analyzed by means of the mean value of the Strain Energy Density (SED) extended at high temperature.
Pasquale Gallo - One of the best experts on this subject based on the ideXlab platform.
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advanced materials for applications at high temperature Fatigue assessment by means of local strain energy density
Advanced Engineering Materials, 2016Co-Authors: Pasquale Gallo, Filippo BertoAbstract:The interest on Fatigue assessment of steel and other alloys at high temperature has increased continuously in the last years. However, high cycle Fatigue of notched components at high temperature has not been deeply investigated experimentally and theoretically. The present paper investigates the accuracy of Strain Energy Density (SED) averaged over a control volume approach when applied to High-Temperature Fatigue data from notched components. In the present work, a large bulk of High-Temperature Fatigue data, taken from the literature and regarding notched components made of different advanced materials, is reanalyzed. In detail: C45 carbon steel at 250 °C, Inconel 718 at 500 °C, and directionally solidified superalloy DZ125 at 850 °C are considered. The main advantage of SED averaged over a control volume is that different geometries can be summarized in a single narrow scatter band. From an industrial viewpoint, the use of a geometry-independent parameter (and Fatigue curve) leads to a considerable advantage in terms of time and cost.
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High temperature Fatigue tests and crack growth in 40CrMoV13.9 notched components
Frattura ed Integrità Strutturale, 2015Co-Authors: Pasquale Gallo, Filippo BertoAbstract:The present paper addresses experimentally the high temperature Fatigue of 40CrMoV13.9 steel and the effect of surface roughness on Fatigue strength and crack initiation. The 40CrMoV13.9 steel is widely used in different engineering high temperature applications among which hot- rolling of metals, where, in order to assure a constant temperature, the rolls are provided with cooling channels. These are the most stressed zone of the rolls where cracks systematically initiate. In order to completely characterize the high temperature behaviour of this steel, firstly uniaxial-tension load controlled Fatigue tests have been conducted at different temperatures up to 650°C. Two geometries are considered: plain specimens and plates weakened by symmetric V-notches. Subsequently, with the aim to investigate the influence of the cooling channels roughness on the high temperature behaviour and the cracks initiation, uniaxial-tension load controlled Fatigue tests have been conducted on plate with central hole at the service temperature of 650°C varying the surface roughness. After a brief review of the recent literature, the experimental procedure is described in detail and the new data from un-notched and notched specimens are summarized in terms of stress range, at the considered temperatures. Finally, Fatigue data from un-notched and notched specimens are re-analysed by means of the mean value of the Strain Energy Density (SED) approach extended at high temperature.
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extension of linear elastic strain energy density approach to high temperature Fatigue and a synthesis of cu be alloy experimental tests
Engineering Solid Mechanics, 2015Co-Authors: Filippo Berto, Pasquale GalloAbstract:Article history: Received October 6, 2014 Accepted 28 January 2015 Available online 29 January 2015 The present paper summarizes the results from uniaxial-tension stress-controlled Fatigue tests performed at different temperatures up to 650°C on Cu-Be specimens. Two geometries are considered: hourglass shaped and plates weakened by a central hole (Cu-Be alloy). The motivation of the present work is that, at the best of authors’ knowledge, only a limited number of papers on these alloys under High-Temperature Fatigue are available in the literature and no results deal with notched components. The Cu-Be specimens Fatigue data are re-analyzed in terms of the mean value of the Strain Energy Density (SED) averaged over a control volume. Thanks to the SED approach it is possible to summarize in a single scatter-band all the Fatigue data, independently of the specimen geometry. © 2015 Growing Science Ltd. All rights reserved.
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Influence of surface roughness on high temperature Fatigue strength and cracks initiation in 40CrMoV13.9 notched components
Theoretical and Applied Fracture Mechanics, 2015Co-Authors: Pasquale Gallo, Filippo BertoAbstract:Abstract The present paper addresses experimentally the high temperature Fatigue of 40CrMoV13.9 steel and the effect of surface roughness on Fatigue strength and cracks initiation. The 40CrMoV13.9 steel considered here is widely used in different engineering high temperature applications among which hot-rolling of metals, where, in order to assure a constant temperature, the rolls are provided with cooling channels. These are the most stressed zone of the rolls where cracks initiate systematically. In order to completely characterize the high temperature behaviour of this steel, firstly uniaxial-tension load controlled Fatigue tests have been conducted at different temperatures up to 650 °C. Two geometries are considered: plain specimens and plates weakened by symmetric V-notches, with opening angle and tip radius being equal to 90° and 1 mm, respectively. Subsequently, with the aim to investigate the influence of the cooling channels roughness on the high temperature behaviour and the cracks initiation, uniaxial-tension load controlled Fatigue tests have been conducted on plate with central hole at the service temperature of 650 °C, varying the surface roughness. After a brief review of the recent literature, the experimental procedure is described in detail and the new data from un-notched and notched specimens are summarized in terms of stress range, at the considered temperatures. Finally, Fatigue data from un-notched and notched specimens are re-analyzed by means of the mean value of the Strain Energy Density (SED) extended at high temperature.
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high temperature Fatigue tests of a cu be alloy and synthesis in terms of linear elastic strain energy density
Key Engineering Materials, 2014Co-Authors: Filippo Berto, Pasquale Gallo, Pierina LazzarinAbstract:The present paper summarises the results from uniaxial-tension stress-controlled Fatigue tests performed at different temperatures up to 650°C on Cu-Be specimens. Two geometries are considered: hourglass shaped and plates weakened by a central hole (Cu-Be alloy). The motivation of the present work is that, at the best of authors’ knowledge, only a limited number of papers on these alloys under High-Temperature Fatigue are available in the literature and no results deal with notched components.The Cu-Be specimens Fatigue data are re-analyzed in terms of the mean value of the Strain Energy Density (SED) averaged over a control volume. Thanks to the SED approach it is possible to summarise in a single scatter-band all the Fatigue data, independently of the specimen geometry.
Megumi Kimura - One of the best experts on this subject based on the ideXlab platform.
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High-Temperature Fatigue properties of austenitic superalloys 718, A286 and 304L
International Journal of Fatigue, 2008Co-Authors: Kazuo Kobayashi, Koji Yamaguchi, Masao Hayakawa, Megumi KimuraAbstract:Abstract High-Temperature Fatigue properties of austenitic superalloys 718, A286, and 304L were investigated in region between 10 2 and 10 7 cycles. The alloys 718 and A286 are precipitation-hardening type austenitic superalloys, and 304L is a solid solution-hardening type austenitic steel. The Fatigue strengths of alloys 718 and A286 in high-cycle region over 10 4 cycles showed a grain size effect. The initiation sites of the fracture were the crystallographic facets corresponding to the austenitic grain size. Therefore the coarse-grain alloys showed the lower Fatigue strength than the fine-grain alloys, because the Fatigue strength is generally inversely proportionate to the initiation defect areas for the Fatigue cracks. In low-cycle region under 10 4 cycles, on the other, the initiation sites of the fracture were the surface of the specimens. This type fracture mode is common for Fatigue fracture of smoothed specimens. The ratio of the Fatigue limit at 10 7 cycles to the tensile strength is extremely low for the coarse-grain alloys compared with the common case of 0.5. From these results Fatigue fracture map is proposed.
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Grain size effect on High-Temperature Fatigue properties of alloy718
Materials Letters, 2004Co-Authors: Kazuo Kobayashi, Koji Yamaguchi, Masao Hayakawa, Megumi KimuraAbstract:Abstract High-Temperature Fatigue properties of Alloy718 with different grain sizes were investigated. For the coarse-grain alloy, the Fatigue strength notably decreased beyond 105 cycles. The Fatigue fracture had originated from facets of the austenite grains. The facets caused a decreasing of Fatigue strengths in a high-cycle region at high temperatures.
Hans-jürgen Christ - One of the best experts on this subject based on the ideXlab platform.
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Isothermal High-Temperature Fatigue behaviour of a near-γ titanium aluminide alloy
Zeitschrift für Metallkunde, 2003Co-Authors: Hans-jürgen Christ, Frank O. R. Fischer, Patric SchallowAbstract:Abstract The High-Temperature Fatigue behaviour of smooth cylindrical specimens of a near-γ-TiAl alloy with duplex microstructure was studied performing total-strain-controlled low-cycle-Fatigue tests in the temperature range 500–750°C. The tests were run in air and high vacuum. Mean stress, environmental degradation (oxygen- and hydrogen-induced embrittlement) and plastic strain range were identified to be the most significant parameters affecting damage evolution. The cyclic stress–strain response was found to depend strongly and characteristically on temperature. Below the brittle-to-ductile-transition temperature (TBD) of about 650°C, cyclic deformation leads to a pronounced initial hardening manifesting itself in an increase of stress amplitude and a decrease of plastic strain range. Conversely, cyclic deformation curves from tests performed above TBD show a marked state of saturation which is established already after few cycles. With increasing temperature, Fatigue life decreases in vacuum. However...
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High-Temperature Fatigue damage mechanisms in near-α titanium alloy IMI 834
International Journal of Fatigue, 1999Co-Authors: S. Hardt, H.j. Maier, Hans-jürgen ChristAbstract:Abstract The High-Temperature Fatigue and creep behaviour of near-α titanium alloy IMI 834 was studied for temperatures up to 650°C. In order to identify the relevant damage mechanisms, the test program involved continuous cycling, dwell tests with hold periods in tension and compression, and asymmetrical strain-time cycles. The dominant damage mechanism was found to change at a temperature of about 600°C. At low test temperatures Fatigue life is largely dependent on the maximum stress of the Fatigue cycle. At high temperatures a brittle oxygen-enriched subsurface layer forms, and thus, environmental degradation governs Fatigue life in High-Temperature low frequency tests. Lamella boundaries present in the bimodal microstructure were seen to deflect small Fatigue cracks, and thus, this microstructure has superior Fatigue properties as compared to an equiaxed one. During long-term High-Temperature exposure, however, significant degradation of the lamella boundaries was observed, and then both microstructures display similar Fatigue properties.
H.j. Maier - One of the best experts on this subject based on the ideXlab platform.
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High-Temperature Fatigue damage mechanisms in near-α titanium alloy IMI 834
International Journal of Fatigue, 1999Co-Authors: S. Hardt, H.j. Maier, Hans-jürgen ChristAbstract:Abstract The High-Temperature Fatigue and creep behaviour of near-α titanium alloy IMI 834 was studied for temperatures up to 650°C. In order to identify the relevant damage mechanisms, the test program involved continuous cycling, dwell tests with hold periods in tension and compression, and asymmetrical strain-time cycles. The dominant damage mechanism was found to change at a temperature of about 600°C. At low test temperatures Fatigue life is largely dependent on the maximum stress of the Fatigue cycle. At high temperatures a brittle oxygen-enriched subsurface layer forms, and thus, environmental degradation governs Fatigue life in High-Temperature low frequency tests. Lamella boundaries present in the bimodal microstructure were seen to deflect small Fatigue cracks, and thus, this microstructure has superior Fatigue properties as compared to an equiaxed one. During long-term High-Temperature exposure, however, significant degradation of the lamella boundaries was observed, and then both microstructures display similar Fatigue properties.
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High-Temperature Fatigue of titanium alloys
Materials at High Temperatures, 1998Co-Authors: H.j. MaierAbstract:The development of High-Temperature titanium alloys has been dominated by the requirements of aerospace industries. Initially, improvements in tensile strength and creep properties were the main interest. Gas inlet temperatures in aero-engines have increased continuously and, nowadays certain components in gas turbine engines that are made out of titanium alloys, such as compressor discs and rotor blades, approach operating temperatures as high as 550°C. As a result of alloy development, near-a alloys capable of operating temperatures up to 600°C are commercially available. These alloys are intended to partially replace heavier nickel-base superalloys, e.g. in the compressor of gas turbine engines and much work has been directed towards understanding High-Temperature Fatigue, creep-Fatigue interaction and oxidation behaviour of titanium alloys. It has been recognized that alloy composition, heat treatment and microstructure all influence strongly the High-Temperature properties of titanium alloys. This re...