The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Sukbong Kang - One of the best experts on this subject based on the ideXlab platform.
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low temperature dynamic recrystallization occurring at a high deformation temperature during hot compression of twin roll cast mg 5 51zn 0 49zr alloy
Scripta Materialia, 2009Co-Authors: Sukbong KangAbstract:Low-temperature dynamic recrystallization, which generally occurs below 200 °C, was found to occur at an elevated deformation temperature as high as 350 and 400 °C as the strain rate employed was increased up to 100 s−1 during hot compression of twin-roll-cast Mg–5.51Zn–0.49Zr (wt.%) alloy. New recrystallized grains formed at the junction of misorientated Dislocation Pile-ups due to the rearrangement of the Dislocation Pile-ups. Both the climbing force acting on the leading Dislocation ahead of the Pile-up and the free-energy change during this rearrangement were calculated.
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Low-temperature dynamic recrystallization occurring at a high deformation temperature during hot compression of twin-roll-cast Mg–5.51Zn–0.49Zr alloy
Scripta Materialia, 2009Co-Authors: Zhiyi Liu, Song Bai, Sukbong KangAbstract:Low-temperature dynamic recrystallization, which generally occurs below 200 °C, was found to occur at an elevated deformation temperature as high as 350 and 400 °C as the strain rate employed was increased up to 100 s−1 during hot compression of twin-roll-cast Mg–5.51Zn–0.49Zr (wt.%) alloy. New recrystallized grains formed at the junction of misorientated Dislocation Pile-ups due to the rearrangement of the Dislocation Pile-ups. Both the climbing force acting on the leading Dislocation ahead of the Pile-up and the free-energy change during this rearrangement were calculated.
A.m. Jansen - One of the best experts on this subject based on the ideXlab platform.
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creep of metals containing high volume fractions of unshearable dispersoids part i modeling the effect of Dislocation Pile ups upon the detachment threshold stress
Acta Materialia, 1997Co-Authors: David C. Dunand, A.m. JansenAbstract:Abstract The high creep resistance of dispersion-strengthened metals is the result of a threshold stress, which is determined in existing models by considering the interaction of a single Dislocation with dispersoids. This paper presents a new model which takes into account the effect of Dislocation Pile-ups upon the detachment threshold stress of dispersion-strengthened metals. First, it is shown that Dislocation Pile-ups are expected to form at dispersoids when the volume fraction and/or size of the dispersoids is large. Then, the equilibrium Dislocation positions within the Pile-ups are calculated and the resulting shear stress exerted upon the detaching Dislocations pinned at the dispersoids is determined. Finally, this Pile-up stress is added to the athermal detachment threshold stress determined with existing models to find a total threshold stress. Calculations for aluminum containing 25 vol.% alumina dispersoids show that the magnitude of the Pile-up stress is comparable to the athermal threshold stress, and thus contributes significantly to the total threshold stress. The model also predicts a creep activation energy much higher than that of the unreinforced metal as a result of the temperature dependence of the number of Dislocations in the Pile-ups.
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Creep of metals containing high volume fractions of unshearable dispersoids—Part I. Modeling the effect of Dislocation Pile-ups upon the detachment threshold stress
Acta Materialia, 1997Co-Authors: David C. Dunand, A.m. JansenAbstract:Abstract The high creep resistance of dispersion-strengthened metals is the result of a threshold stress, which is determined in existing models by considering the interaction of a single Dislocation with dispersoids. This paper presents a new model which takes into account the effect of Dislocation Pile-ups upon the detachment threshold stress of dispersion-strengthened metals. First, it is shown that Dislocation Pile-ups are expected to form at dispersoids when the volume fraction and/or size of the dispersoids is large. Then, the equilibrium Dislocation positions within the Pile-ups are calculated and the resulting shear stress exerted upon the detaching Dislocations pinned at the dispersoids is determined. Finally, this Pile-up stress is added to the athermal detachment threshold stress determined with existing models to find a total threshold stress. Calculations for aluminum containing 25 vol.% alumina dispersoids show that the magnitude of the Pile-up stress is comparable to the athermal threshold stress, and thus contributes significantly to the total threshold stress. The model also predicts a creep activation energy much higher than that of the unreinforced metal as a result of the temperature dependence of the number of Dislocations in the Pile-ups.
Xibin Wang - One of the best experts on this subject based on the ideXlab platform.
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a novel constitutive model for ti 6al 4v alloy based on Dislocation Pile up theory
Materials Science and Technology, 2017Co-Authors: Tianfeng Zhou, Zhiqiang Liang, Jiangtao Che, Yichuan Zhang, Xibin WangAbstract:ABSTRACTThe mechanical properties of the titanium alloy Ti–6Al–4V, which vary with the specimen size under different temperatures, are studied through the Split Hopkinson Pressure Bar (SHPB) test and the quasi-static tensile test to determine the parameters for the classical Johnson-Cook (JC) constitutive model. Based on the Dislocation Pile-up theory, the classical JC constitutive model is modified by adding a grain strain term Δσ to consider the influence of grain size. The SHPB and tensile tests are analysed using a finite element method simulation. Compared with the experimental results, the simulation results based on the modified JC model exhibit a much higher calculation accuracy than that of the classical JC model.
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A novel constitutive model for Ti–6Al–4V alloy based on Dislocation Pile-up theory
Materials Science and Technology, 2017Co-Authors: Tianfeng Zhou, Zhiqiang Liang, Jiangtao Che, Yichuan Zhang, Xibin WangAbstract:ABSTRACTThe mechanical properties of the titanium alloy Ti–6Al–4V, which vary with the specimen size under different temperatures, are studied through the Split Hopkinson Pressure Bar (SHPB) test and the quasi-static tensile test to determine the parameters for the classical Johnson-Cook (JC) constitutive model. Based on the Dislocation Pile-up theory, the classical JC constitutive model is modified by adding a grain strain term Δσ to consider the influence of grain size. The SHPB and tensile tests are analysed using a finite element method simulation. Compared with the experimental results, the simulation results based on the modified JC model exhibit a much higher calculation accuracy than that of the classical JC model.
David C. Dunand - One of the best experts on this subject based on the ideXlab platform.
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creep of metals containing high volume fractions of unshearable dispersoids part i modeling the effect of Dislocation Pile ups upon the detachment threshold stress
Acta Materialia, 1997Co-Authors: David C. Dunand, A.m. JansenAbstract:Abstract The high creep resistance of dispersion-strengthened metals is the result of a threshold stress, which is determined in existing models by considering the interaction of a single Dislocation with dispersoids. This paper presents a new model which takes into account the effect of Dislocation Pile-ups upon the detachment threshold stress of dispersion-strengthened metals. First, it is shown that Dislocation Pile-ups are expected to form at dispersoids when the volume fraction and/or size of the dispersoids is large. Then, the equilibrium Dislocation positions within the Pile-ups are calculated and the resulting shear stress exerted upon the detaching Dislocations pinned at the dispersoids is determined. Finally, this Pile-up stress is added to the athermal detachment threshold stress determined with existing models to find a total threshold stress. Calculations for aluminum containing 25 vol.% alumina dispersoids show that the magnitude of the Pile-up stress is comparable to the athermal threshold stress, and thus contributes significantly to the total threshold stress. The model also predicts a creep activation energy much higher than that of the unreinforced metal as a result of the temperature dependence of the number of Dislocations in the Pile-ups.
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Creep of metals containing high volume fractions of unshearable dispersoids—Part I. Modeling the effect of Dislocation Pile-ups upon the detachment threshold stress
Acta Materialia, 1997Co-Authors: David C. Dunand, A.m. JansenAbstract:Abstract The high creep resistance of dispersion-strengthened metals is the result of a threshold stress, which is determined in existing models by considering the interaction of a single Dislocation with dispersoids. This paper presents a new model which takes into account the effect of Dislocation Pile-ups upon the detachment threshold stress of dispersion-strengthened metals. First, it is shown that Dislocation Pile-ups are expected to form at dispersoids when the volume fraction and/or size of the dispersoids is large. Then, the equilibrium Dislocation positions within the Pile-ups are calculated and the resulting shear stress exerted upon the detaching Dislocations pinned at the dispersoids is determined. Finally, this Pile-up stress is added to the athermal detachment threshold stress determined with existing models to find a total threshold stress. Calculations for aluminum containing 25 vol.% alumina dispersoids show that the magnitude of the Pile-up stress is comparable to the athermal threshold stress, and thus contributes significantly to the total threshold stress. The model also predicts a creep activation energy much higher than that of the unreinforced metal as a result of the temperature dependence of the number of Dislocations in the Pile-ups.
Tianfeng Zhou - One of the best experts on this subject based on the ideXlab platform.
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a novel constitutive model for ti 6al 4v alloy based on Dislocation Pile up theory
Materials Science and Technology, 2017Co-Authors: Tianfeng Zhou, Zhiqiang Liang, Jiangtao Che, Yichuan Zhang, Xibin WangAbstract:ABSTRACTThe mechanical properties of the titanium alloy Ti–6Al–4V, which vary with the specimen size under different temperatures, are studied through the Split Hopkinson Pressure Bar (SHPB) test and the quasi-static tensile test to determine the parameters for the classical Johnson-Cook (JC) constitutive model. Based on the Dislocation Pile-up theory, the classical JC constitutive model is modified by adding a grain strain term Δσ to consider the influence of grain size. The SHPB and tensile tests are analysed using a finite element method simulation. Compared with the experimental results, the simulation results based on the modified JC model exhibit a much higher calculation accuracy than that of the classical JC model.
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A novel constitutive model for Ti–6Al–4V alloy based on Dislocation Pile-up theory
Materials Science and Technology, 2017Co-Authors: Tianfeng Zhou, Zhiqiang Liang, Jiangtao Che, Yichuan Zhang, Xibin WangAbstract:ABSTRACTThe mechanical properties of the titanium alloy Ti–6Al–4V, which vary with the specimen size under different temperatures, are studied through the Split Hopkinson Pressure Bar (SHPB) test and the quasi-static tensile test to determine the parameters for the classical Johnson-Cook (JC) constitutive model. Based on the Dislocation Pile-up theory, the classical JC constitutive model is modified by adding a grain strain term Δσ to consider the influence of grain size. The SHPB and tensile tests are analysed using a finite element method simulation. Compared with the experimental results, the simulation results based on the modified JC model exhibit a much higher calculation accuracy than that of the classical JC model.