The Experts below are selected from a list of 64530 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.
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the effect of coarse second phase particles on the rate of grain Refinement during severe deformation Processing
Acta Materialia, 2003Co-Authors: P J Apps, Jacob R Bowen, P B PrangnellAbstract:Abstract The effect of second-phase particles on the rate of grain Refinement during severe deformation Processing has been investigated, by comparing the microstructure evolution in an AA8079 aluminium alloy, containing 2.5 vol.% of ~2 μm particles, with that in a high purity, single-phase, Al-0.13% Mg alloy, deformed identically by ECAE to an effective strain of ten. The materials were analysed by high-resolution EBSD orientation mapping, which revealed that grain Refinement occurred at a dramatically higher rate in the particle-containing alloy. A submicron grain structure could be achieved by an effective strain of only five in the particle-containing alloy, compared to ten in the single-phase material. The mechanisms that contribute to this acceleration of the grain Refinement Process are discussed.
Y T Zhu - One of the best experts on this subject based on the ideXlab platform.
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concurrent microstructural evolution of ferrite and austenite in a duplex stainless steel Processed by high pressure torsion
Acta Materialia, 2014Co-Authors: Yang Cao, Y B Wang, X Z Liao, Megumi Kawasaki, Simon P Ringer, Terence G Langdon, Y T ZhuAbstract:A duplex stainless steel with approximately equal volume fractions of ferrite and austenite was Processed by high-pressure torsion. Nano-indentation, electron backscatter diffraction and transmission electron microscopy were used to investigate the hardness and microstructure evolutions of the steel. Despite the different strain-hardening rates of individual ferrite and austenite, the microstructures of the two phases evolved concurrently in such a way that the neighbouring two phases always maintained similar hardness. While the plastic deformation and grain Refinement of ferrite occurred mainly via dislocation activities, the plastic deformation and grain Refinement Process of austenite were more complicated and included deformation twinning and de-twinning in coarse grains, grain Refinement by twinning and dislocation–twin interactions, de-twinning in ultrafine grains and twin boundary subdivision.
Terence G Langdon - One of the best experts on this subject based on the ideXlab platform.
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concurrent microstructural evolution of ferrite and austenite in a duplex stainless steel Processed by high pressure torsion
Acta Materialia, 2014Co-Authors: Yang Cao, Y B Wang, X Z Liao, Megumi Kawasaki, Simon P Ringer, Terence G Langdon, Y T ZhuAbstract:A duplex stainless steel with approximately equal volume fractions of ferrite and austenite was Processed by high-pressure torsion. Nano-indentation, electron backscatter diffraction and transmission electron microscopy were used to investigate the hardness and microstructure evolutions of the steel. Despite the different strain-hardening rates of individual ferrite and austenite, the microstructures of the two phases evolved concurrently in such a way that the neighbouring two phases always maintained similar hardness. While the plastic deformation and grain Refinement of ferrite occurred mainly via dislocation activities, the plastic deformation and grain Refinement Process of austenite were more complicated and included deformation twinning and de-twinning in coarse grains, grain Refinement by twinning and dislocation–twin interactions, de-twinning in ultrafine grains and twin boundary subdivision.
Megumi Kawasaki - One of the best experts on this subject based on the ideXlab platform.
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concurrent microstructural evolution of ferrite and austenite in a duplex stainless steel Processed by high pressure torsion
Acta Materialia, 2014Co-Authors: Yang Cao, Y B Wang, X Z Liao, Megumi Kawasaki, Simon P Ringer, Terence G Langdon, Y T ZhuAbstract:A duplex stainless steel with approximately equal volume fractions of ferrite and austenite was Processed by high-pressure torsion. Nano-indentation, electron backscatter diffraction and transmission electron microscopy were used to investigate the hardness and microstructure evolutions of the steel. Despite the different strain-hardening rates of individual ferrite and austenite, the microstructures of the two phases evolved concurrently in such a way that the neighbouring two phases always maintained similar hardness. While the plastic deformation and grain Refinement of ferrite occurred mainly via dislocation activities, the plastic deformation and grain Refinement Process of austenite were more complicated and included deformation twinning and de-twinning in coarse grains, grain Refinement by twinning and dislocation–twin interactions, de-twinning in ultrafine grains and twin boundary subdivision.
