The Experts below are selected from a list of 18 Experts worldwide ranked by ideXlab platform
Alan A Luo - One of the best experts on this subject based on the ideXlab platform.
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dependence of Flow strength and deformation mechanisms in common wrought and die cast magnesium alloys on orientation strain rate and temperature
Journal of Magnesium and Alloys, 2013Co-Authors: W R Tyson, R Eagleson, R Zavadil, Zheng Liu, Pingli Mao, C Y Wang, S I Hill, Alan A LuoAbstract:Abstract The controlling plastic deformation mechanisms (i.e. slip or twinning) and the structural crash performance of Mg alloys are strongly influenced by loading mode, texture and microstructure. This paper summarizes the main results from an experimental program to assess these effects for commercial Mg alloy extrusions (AM30 and AZ31), sheet (AZ31), and high pressure die castings (HPDC, AM50 and AM60). Uniaxial tensile and compressive tests were performed over a wide range of strain rate and temperature (i.e. 0.00075–2800 s−1 and 100 °C to −150 °C) using conventional servo-hydraulic and high-strain-rate universal test machines and a split-Hopkinson-bar (SHB) apparatus. In primarily-slip-dominant deformation, the true Stress–strain curves showed approximate power-law behavior, and the effects of strain rate and temperature on yield strength could be approximately described by constitutive equations linearly dependent on the rate parameter, T ln ( 5.3 × 10 7 / ɛ ˙ ) where T is test temperature in Kelvin and ɛ ˙ is strain rate in s−1. In primarily-twin-dominant deformation, the effects of strain rate and temperature on yield and Initial Flow Stress were negligible or small from quasi-static to 2800 s−1 owing to the athermal characteristics of mechanical twinning; the effects may become more pronounced with exhaustion of twinning and increasing proportion of slip.
David Porter - One of the best experts on this subject based on the ideXlab platform.
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modeling of the high temperature Flow behavior of stabilized 12 27 wt cr ferritic stainless steels
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: Saara Mehtonen, L P Karjalainen, David PorterAbstract:Abstract Constitutive equations and a Flow Stress model for the hot deformation of stabilized ferritic stainless steels with Cr contents between 12 and 27 wt% have been developed. The equations are based on compression tests in a Gleeble thermomechanical simulator to the strain of 0.4 at temperatures of 950–1050 °C at the strain rates of 0.01, 0.1 and 1 s −1 . A pronounced influence of dynamic recovery on the Flow curves of all steels was evident. In the constitutive equations, the activation energy for deformation decreased systemically from 359 kJ/mol to 329 kJ/mol as the Cr content increased from 12 to 27 wt%, and the interpretation of this peculiarity is discussed. A Flow Stress model developed, based on dislocation density, was found to predict quite accurately the experimental Flow curves at the deformation temperatures and strain rates applied. Also reasonable values for dislocation densities could be evaluated from the model. The strain independent work-hardening parameter, U , which is a measure of the rate of dislocation immobilization, and the Initial Flow Stress σ 0 were found to be dependent on the deformation conditions and the Cr content. In contrast, the recovery parameter, Ω , which represents the remobilization of immobile dislocations, was found to be independent of the Cr content.
W R Tyson - One of the best experts on this subject based on the ideXlab platform.
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dependence of Flow strength and deformation mechanisms in common wrought and die cast magnesium alloys on orientation strain rate and temperature
Journal of Magnesium and Alloys, 2013Co-Authors: W R Tyson, R Eagleson, R Zavadil, Zheng Liu, Pingli Mao, C Y Wang, S I Hill, Alan A LuoAbstract:Abstract The controlling plastic deformation mechanisms (i.e. slip or twinning) and the structural crash performance of Mg alloys are strongly influenced by loading mode, texture and microstructure. This paper summarizes the main results from an experimental program to assess these effects for commercial Mg alloy extrusions (AM30 and AZ31), sheet (AZ31), and high pressure die castings (HPDC, AM50 and AM60). Uniaxial tensile and compressive tests were performed over a wide range of strain rate and temperature (i.e. 0.00075–2800 s−1 and 100 °C to −150 °C) using conventional servo-hydraulic and high-strain-rate universal test machines and a split-Hopkinson-bar (SHB) apparatus. In primarily-slip-dominant deformation, the true Stress–strain curves showed approximate power-law behavior, and the effects of strain rate and temperature on yield strength could be approximately described by constitutive equations linearly dependent on the rate parameter, T ln ( 5.3 × 10 7 / ɛ ˙ ) where T is test temperature in Kelvin and ɛ ˙ is strain rate in s−1. In primarily-twin-dominant deformation, the effects of strain rate and temperature on yield and Initial Flow Stress were negligible or small from quasi-static to 2800 s−1 owing to the athermal characteristics of mechanical twinning; the effects may become more pronounced with exhaustion of twinning and increasing proportion of slip.
Saara Mehtonen - One of the best experts on this subject based on the ideXlab platform.
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modeling of the high temperature Flow behavior of stabilized 12 27 wt cr ferritic stainless steels
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: Saara Mehtonen, L P Karjalainen, David PorterAbstract:Abstract Constitutive equations and a Flow Stress model for the hot deformation of stabilized ferritic stainless steels with Cr contents between 12 and 27 wt% have been developed. The equations are based on compression tests in a Gleeble thermomechanical simulator to the strain of 0.4 at temperatures of 950–1050 °C at the strain rates of 0.01, 0.1 and 1 s −1 . A pronounced influence of dynamic recovery on the Flow curves of all steels was evident. In the constitutive equations, the activation energy for deformation decreased systemically from 359 kJ/mol to 329 kJ/mol as the Cr content increased from 12 to 27 wt%, and the interpretation of this peculiarity is discussed. A Flow Stress model developed, based on dislocation density, was found to predict quite accurately the experimental Flow curves at the deformation temperatures and strain rates applied. Also reasonable values for dislocation densities could be evaluated from the model. The strain independent work-hardening parameter, U , which is a measure of the rate of dislocation immobilization, and the Initial Flow Stress σ 0 were found to be dependent on the deformation conditions and the Cr content. In contrast, the recovery parameter, Ω , which represents the remobilization of immobile dislocations, was found to be independent of the Cr content.
S I Hill - One of the best experts on this subject based on the ideXlab platform.
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dependence of Flow strength and deformation mechanisms in common wrought and die cast magnesium alloys on orientation strain rate and temperature
Journal of Magnesium and Alloys, 2013Co-Authors: W R Tyson, R Eagleson, R Zavadil, Zheng Liu, Pingli Mao, C Y Wang, S I Hill, Alan A LuoAbstract:Abstract The controlling plastic deformation mechanisms (i.e. slip or twinning) and the structural crash performance of Mg alloys are strongly influenced by loading mode, texture and microstructure. This paper summarizes the main results from an experimental program to assess these effects for commercial Mg alloy extrusions (AM30 and AZ31), sheet (AZ31), and high pressure die castings (HPDC, AM50 and AM60). Uniaxial tensile and compressive tests were performed over a wide range of strain rate and temperature (i.e. 0.00075–2800 s−1 and 100 °C to −150 °C) using conventional servo-hydraulic and high-strain-rate universal test machines and a split-Hopkinson-bar (SHB) apparatus. In primarily-slip-dominant deformation, the true Stress–strain curves showed approximate power-law behavior, and the effects of strain rate and temperature on yield strength could be approximately described by constitutive equations linearly dependent on the rate parameter, T ln ( 5.3 × 10 7 / ɛ ˙ ) where T is test temperature in Kelvin and ɛ ˙ is strain rate in s−1. In primarily-twin-dominant deformation, the effects of strain rate and temperature on yield and Initial Flow Stress were negligible or small from quasi-static to 2800 s−1 owing to the athermal characteristics of mechanical twinning; the effects may become more pronounced with exhaustion of twinning and increasing proportion of slip.