The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Chris P Heason - One of the best experts on this subject based on the ideXlab platform.
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grain structure formation during friction stir welding observed by the stop action technique
Acta Materialia, 2005Co-Authors: P B Prangnell, Chris P HeasonAbstract:Abstract Experiments have been carried out to ‘freeze’ the friction stir welding process by stopping the tool and immediately quenching the work piece in an Al-2195 plate welded under typical conditions. Sectioning through the ‘frozen’ weld keyhole with the tool in place has allowed the microstructure development, leading to the formation of the ultrafine grained nugget material, to be directly observed as fresh material encounters the Deformation field surrounding the rotating pin. The grain refinement process is shown to be driven by grain subdivision at the colder periphery of the tools Deformation zone, and the geometric effects of strain, which together reduce the overall high angle boundary spacing with Increasing Deformation. However, it also involves thermally activated high angle grain boundary migration, which increases as the temperature rises towards the tool. The higher temperature latter stages of the refinement process are closely reminiscent of geometric dynamic recrystallisation seen in high strain hot torsion experiments. The nugget grain structure has also been found to become more equiaxed and coarsens slightly, due to static annealing in the thermal wake of the tool.
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grain structure formation during friction stir welding observed by the stop action technique
Acta Materialia, 2005Co-Authors: P B Prangnell, Chris P HeasonAbstract:Abstract Experiments have been carried out to ‘freeze’ the friction stir welding process by stopping the tool and immediately quenching the work piece in an Al-2195 plate welded under typical conditions. Sectioning through the ‘frozen’ weld keyhole with the tool in place has allowed the microstructure development, leading to the formation of the ultrafine grained nugget material, to be directly observed as fresh material encounters the Deformation field surrounding the rotating pin. The grain refinement process is shown to be driven by grain subdivision at the colder periphery of the tools Deformation zone, and the geometric effects of strain, which together reduce the overall high angle boundary spacing with Increasing Deformation. However, it also involves thermally activated high angle grain boundary migration, which increases as the temperature rises towards the tool. The higher temperature latter stages of the refinement process are closely reminiscent of geometric dynamic recrystallisation seen in high strain hot torsion experiments. The nugget grain structure has also been found to become more equiaxed and coarsens slightly, due to static annealing in the thermal wake of the tool.
P B Prangnell - One of the best experts on this subject based on the ideXlab platform.
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grain structure formation during friction stir welding observed by the stop action technique
Acta Materialia, 2005Co-Authors: P B Prangnell, Chris P HeasonAbstract:Abstract Experiments have been carried out to ‘freeze’ the friction stir welding process by stopping the tool and immediately quenching the work piece in an Al-2195 plate welded under typical conditions. Sectioning through the ‘frozen’ weld keyhole with the tool in place has allowed the microstructure development, leading to the formation of the ultrafine grained nugget material, to be directly observed as fresh material encounters the Deformation field surrounding the rotating pin. The grain refinement process is shown to be driven by grain subdivision at the colder periphery of the tools Deformation zone, and the geometric effects of strain, which together reduce the overall high angle boundary spacing with Increasing Deformation. However, it also involves thermally activated high angle grain boundary migration, which increases as the temperature rises towards the tool. The higher temperature latter stages of the refinement process are closely reminiscent of geometric dynamic recrystallisation seen in high strain hot torsion experiments. The nugget grain structure has also been found to become more equiaxed and coarsens slightly, due to static annealing in the thermal wake of the tool.
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grain structure formation during friction stir welding observed by the stop action technique
Acta Materialia, 2005Co-Authors: P B Prangnell, Chris P HeasonAbstract:Abstract Experiments have been carried out to ‘freeze’ the friction stir welding process by stopping the tool and immediately quenching the work piece in an Al-2195 plate welded under typical conditions. Sectioning through the ‘frozen’ weld keyhole with the tool in place has allowed the microstructure development, leading to the formation of the ultrafine grained nugget material, to be directly observed as fresh material encounters the Deformation field surrounding the rotating pin. The grain refinement process is shown to be driven by grain subdivision at the colder periphery of the tools Deformation zone, and the geometric effects of strain, which together reduce the overall high angle boundary spacing with Increasing Deformation. However, it also involves thermally activated high angle grain boundary migration, which increases as the temperature rises towards the tool. The higher temperature latter stages of the refinement process are closely reminiscent of geometric dynamic recrystallisation seen in high strain hot torsion experiments. The nugget grain structure has also been found to become more equiaxed and coarsens slightly, due to static annealing in the thermal wake of the tool.
Y C Lin - One of the best experts on this subject based on the ideXlab platform.
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precipitation behavior of a β quenched ti 5al 5mo 5v 1cr 1fe alloy during high temperature compression
Materials Characterization, 2019Co-Authors: Qianwei Wang, Y C Lin, Yuqiang Jiang, Xingang Liu, Xiaoyong Zhang, Dongdong Chen, Chao Chen, Kechao ZhouAbstract:Abstract The precipitation behavior of α phase in a β-quenched Ti-55511 alloy during high-temperature compression is investigated. The influences of Deformation parameters on the flow characteristics, microstructural evolution, as well as the precipitation behavior of α phase, are discussed. Results show that the flow stress features and the dominant softening mechanism are sensitive to the Deformation parameters. At low strain rates or high Deformation temperatures, the main softening mechanism is dynamic recovery. But, the dynamic recrystallization becomes the dominant softening mechanism at high strain rates or low temperatures. At low strain rates, the continuous strengthening, induced by the pinning effect of α precipitates, happens at the late period of Deformation. Distribution of α precipitates is not greatly affected by Deformation parameters. In the region near β grain boundary, α precipitates are densely distributed with few orientations. While in the central region of β grain, the α precipitates are distributed a bit more sparsely with several scattering orientations. In addition, with Increasing Deformation temperature, the content, aspect ratio and size of α phases decrease. However, with Increasing strain rate, the content, aspect ratio and size first increase and then decrease. Furthermore, the peak value of aspect ratio appears at 0.01 s−1.
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dislocation substructures evolution and an adaptive network based fuzzy inference system model for constitutive behavior of a ni based superalloy during hot Deformation
Journal of Alloys and Compounds, 2017Co-Authors: Dongdong Chen, Y C Lin, Mingsong Chen, Ying Zhou, Dongxu WenAbstract:Abstract The isothermal compressive tests with strain rates of (0.001–1) s−1 and Deformation temperatures of (920–1040) °C were conducted to study the high-temperature Deformation behavior of a Ni-based superalloy. The experimental results show that the true stress decreases with Increasing Deformation temperature or decreasing strain rate. The effects of Deformation temperature and strain rate on dislocation substructures are significant. Based on the experimental data, an adaptive-network-based fuzzy inference system (ANFIS) model is constructed for describing the high-temperature Deformation behavior of the studied Ni-based superalloy. The inputs of the constructed ANFIS model are Deformation parameters (Deformation temperature, strain rate and true strain), while the output is true stress. The optimal numbers and types of membership function for the above three input variables are 5-4-5 and ‘triangle-shape, triangle-shape, bell-shape’, respectively. Comparing the experimental and predicted results, it is found that the constructed ANFIS model can be used to accurately predict the high-temperature Deformation behavior of the studied Ni-based superalloy.
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modeling of flow stress of 42crmo steel under hot compression
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009Co-Authors: Y C Lin, Mingsong Chen, Jun ZhangAbstract:Abstract The compressive Deformation behavior of 42CrMo steel was investigated at temperatures from 850 °C to 1150 °C and strain rates from 0.01 s −1 to 50 s −1 on a Gleeble-1500 thermo-simulation machine. The results show that the true stress–true strain curves exhibit peak stresses at small strains, then the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. The stress level decreases with Increasing Deformation temperature and decreasing strain rate, which can be represented by a Zener–Hollomon parameter in an exponent-type equation. A revised model describing the relationships of the flow stress, strain rate and temperature of the 42CrMo steel at elevated temperatures is proposed by compensation of strain. The stress–strain relations of 42CrMo steel predicted by the proposed models agree well with experimental results.
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constitutive modeling for elevated temperature flow behavior of 42crmo steel
Computational Materials Science, 2008Co-Authors: Y C Lin, Mingsong Chen, Jue ZhongAbstract:Abstract In order to study the workability and establish the optimum hot formation processing parameters for 42CrMo steel, the compressive Deformation behavior of 42CrMo steel was investigated at the temperatures from 850 to 1150 °C and strain rates from 0.01 to 50 s−1 on Gleeble-1500 thermo-simulation machine. The results show that the true stress–true strain curves exhibit a peak stress at a small strain, after which the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. The flow stress obtained from experiments consists of four different stage, i.e., Stage I (Work hardening stage), Stage II (Stable stage), Stage III (Softening stage) and Stage IV (Steady stage). The stress level decreases with Increasing Deformation temperature and decreasing strain rate, which can be represented by a Zener–Hollomon parameter in an exponent-type equation. A revised model describing the relationships of the flow stress, strain rate and temperature of 42CrMo steel at elevated temperatures is proposed by compensation of strain and strain rate. The stress–strain values of 42CrMo steel predicted by the proposed model well agree with experimental results, which confirmed that the revised Deformation constitutive equation gives an accurate and precise estimate for the flow stress of 42CrMo steel.
Mingsong Chen - One of the best experts on this subject based on the ideXlab platform.
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dislocation substructures evolution and an adaptive network based fuzzy inference system model for constitutive behavior of a ni based superalloy during hot Deformation
Journal of Alloys and Compounds, 2017Co-Authors: Dongdong Chen, Y C Lin, Mingsong Chen, Ying Zhou, Dongxu WenAbstract:Abstract The isothermal compressive tests with strain rates of (0.001–1) s−1 and Deformation temperatures of (920–1040) °C were conducted to study the high-temperature Deformation behavior of a Ni-based superalloy. The experimental results show that the true stress decreases with Increasing Deformation temperature or decreasing strain rate. The effects of Deformation temperature and strain rate on dislocation substructures are significant. Based on the experimental data, an adaptive-network-based fuzzy inference system (ANFIS) model is constructed for describing the high-temperature Deformation behavior of the studied Ni-based superalloy. The inputs of the constructed ANFIS model are Deformation parameters (Deformation temperature, strain rate and true strain), while the output is true stress. The optimal numbers and types of membership function for the above three input variables are 5-4-5 and ‘triangle-shape, triangle-shape, bell-shape’, respectively. Comparing the experimental and predicted results, it is found that the constructed ANFIS model can be used to accurately predict the high-temperature Deformation behavior of the studied Ni-based superalloy.
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modeling of flow stress of 42crmo steel under hot compression
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009Co-Authors: Y C Lin, Mingsong Chen, Jun ZhangAbstract:Abstract The compressive Deformation behavior of 42CrMo steel was investigated at temperatures from 850 °C to 1150 °C and strain rates from 0.01 s −1 to 50 s −1 on a Gleeble-1500 thermo-simulation machine. The results show that the true stress–true strain curves exhibit peak stresses at small strains, then the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. The stress level decreases with Increasing Deformation temperature and decreasing strain rate, which can be represented by a Zener–Hollomon parameter in an exponent-type equation. A revised model describing the relationships of the flow stress, strain rate and temperature of the 42CrMo steel at elevated temperatures is proposed by compensation of strain. The stress–strain relations of 42CrMo steel predicted by the proposed models agree well with experimental results.
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constitutive modeling for elevated temperature flow behavior of 42crmo steel
Computational Materials Science, 2008Co-Authors: Y C Lin, Mingsong Chen, Jue ZhongAbstract:Abstract In order to study the workability and establish the optimum hot formation processing parameters for 42CrMo steel, the compressive Deformation behavior of 42CrMo steel was investigated at the temperatures from 850 to 1150 °C and strain rates from 0.01 to 50 s−1 on Gleeble-1500 thermo-simulation machine. The results show that the true stress–true strain curves exhibit a peak stress at a small strain, after which the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. The flow stress obtained from experiments consists of four different stage, i.e., Stage I (Work hardening stage), Stage II (Stable stage), Stage III (Softening stage) and Stage IV (Steady stage). The stress level decreases with Increasing Deformation temperature and decreasing strain rate, which can be represented by a Zener–Hollomon parameter in an exponent-type equation. A revised model describing the relationships of the flow stress, strain rate and temperature of 42CrMo steel at elevated temperatures is proposed by compensation of strain and strain rate. The stress–strain values of 42CrMo steel predicted by the proposed model well agree with experimental results, which confirmed that the revised Deformation constitutive equation gives an accurate and precise estimate for the flow stress of 42CrMo steel.
Zuzanka Trojanová - One of the best experts on this subject based on the ideXlab platform.
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influence of accumulative roll bonding on the texture and tensile properties of an az31 magnesium alloy sheets
Materials, 2018Co-Authors: Zuzanka Trojanová, Kristýna Halmešová, Pavel Lukáč, Ján Džugan, Peter Minárik, Gergely Nemeth, Jan BohlenAbstract:Deformation behaviour of rolled AZ31 sheets that were subjected to the accumulative roll bonding was investigated. Substantially refined microstructure of samples was achieved after the first and second pass through the rolling mill. Sheets texture was investigated using an X-ray diffractometer. Samples for tensile tests were cut either parallel or perpendicular to the rolling direction. Tensile tests were performed at temperatures ranging from room temperature up to 300 °C. Tensile plastic anisotropy, different from the anisotropy observed in AZ31 sheets by other authors, was observed. This anisotropy decreases with an Increasing number of rolling passes and Increasing Deformation temperature. Grain refinement and texture are the crucial factors influencing the Deformation behaviour.
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internal stress and thermally activated dislocation motion in an az63 magnesium alloy
Materials Chemistry and Physics, 2011Co-Authors: Zuzanka Trojanová, Gergely Nemeth, Kristian Mathis, P Lukac, Frantisek ChmelikAbstract:Abstract Magnesium alloy AZ63 was deformed at temperatures between room temperature and 300 °C. Stress relaxation tests were performed in order to reveal the physical base of the Deformation process/-es. Internal and effective components of the applied stress have been estimated. Very high values of the internal stress estimated at room temperature decrease rapidly with Increasing Deformation temperature. The apparent activation volume decreases with Increasing effective stress. Estimated values of the activation volume as well as the activation enthalpy indicate that the main thermally activated process is connected with the rapid decrease of the internal stress.
