ABSTRACT The argument for a pedagogy which embraces visual and multimodal representation is well ... more ABSTRACT The argument for a pedagogy which embraces visual and multimodal representation is well established in academic circles (Kress & Van Leeuwen, 1996; New London Group, 1996; Cope & Kalantzis, 2000) and a plethora of literacies congregate around the ever-...
ABSTRACT Texture development and grain refinement of interstitial-free (IF) steel as a function o... more ABSTRACT Texture development and grain refinement of interstitial-free (IF) steel as a function of ideal simple shear or torsion was undertaken for up to 8 pressings, Route BC. Dominant texture components evolved after a single pass and remained correspondent for all subsequent passes. End-cycle (4 and 8 pass) orientation distribution functions (ODFs) showed an increased spread of contour levels and the re-appearance of texture components similar to the 0-pass condition. Rotation of torsion components away from their ideal pole figure (PF) orientations increased at mid-cycle and decreased to almost equivalent levels after end-cycle passes. This is attributed to the principle slip directions of BCC structures aligning with the shear direction.
One of the impediments to the uptake of wrought magnesium alloys has been their percei-ved poor f... more One of the impediments to the uptake of wrought magnesium alloys has been their percei-ved poor forming characteristics when compared to aluminium. Extrusion speeds for magnesium are typically quoted as between 2/3 and 1/3 that of aluminium [1], with a con-comitant ...
ABSTRACT Texture evolution during the microforming of severely deformed copper was studied by exp... more ABSTRACT Texture evolution during the microforming of severely deformed copper was studied by experimental measurements using X-ray and Electron Back-Scattered Diffraction techniques and by numerical simulation. The simulation includes the finite element analysis of micro-cup Swift tests on copper pre-deformed by different number of ECAP passes and polycrystal modelling of texture evolution. It was shown that FE simulations combined with a posteriori polycrystal plasticity modelling is an effective tool for the modelling of the texture development in the cup-drawing process. The obtained good agreement between the simulations and the measured texture development revealed that the rigid body rotations of the material during the cup test play a very important role in the texture evolution. Through-thickness variations of the texture were also observed both in experiments and simulations and are shown to be the result of the differences in the accumulated strains and the rigid body rotations across the cup wall.
ABSTRACT Interstitial-free steel and OFHC copper were subjected to 8 passes, route BC room temper... more ABSTRACT Interstitial-free steel and OFHC copper were subjected to 8 passes, route BC room temperature ECAE followed by cold-rolling up to 97.5% thickness reduction. Uniaxial tensile tests and Electron Back-Scattering Diffraction were used to characterise the evolution in mechanical properties, microstructure refinement and micro-texture. IF-steel showed continuous increase in strength whereas Cu returned reduced strength and a small gain in ductility at 97.5% reduction. In both metals substructure refinement was accompanied by an increase in high-angle boundary fraction, average misorientation and a slight increase in Σ3 boundaries. An evolution of crystallographic orientations from negative shear to predominantly cold-rolled textures after 95% and 97.5% reduction was observed in both metals.
ABSTRACT An extra-low-carbon steel was alloyed with 0.78 wt% Cr and subjected to three different ... more ABSTRACT An extra-low-carbon steel was alloyed with 0.78 wt% Cr and subjected to three different processing schedules involving: (i) warm rolling to 65% reduction at 640°C, (ii) warm rolling to 80% reduction at 580°C and (iii) warm rolling to 65% reduction at 640°C followed by cold rolling to 40% reduction. Increasing the severity of the deformation resulted in an increase in the number of grains containing in-grain shear bands. X-ray bulk texture analysis indicates that the γ-fibre intensity was slightly higher in the steel warm rolled at 580 °C than at 640°C and after cold rolling. Transmission electron microscopy and atom probe tomography revealed that Cr carbides were formed after all processing schedules. Carbon segregation to dislocations was also observed. Although the addition of 0.78 wt% Cr produced a volume fraction of carbides that was three orders of magnitude higher than those previously observed in 0.48 wt% Cr steels, a significant amount of solute Cr remained confined in the matrix and did not lead to any further depletion of the solute carbon.
ABSTRACT The argument for a pedagogy which embraces visual and multimodal representation is well ... more ABSTRACT The argument for a pedagogy which embraces visual and multimodal representation is well established in academic circles (Kress & Van Leeuwen, 1996; New London Group, 1996; Cope & Kalantzis, 2000) and a plethora of literacies congregate around the ever-...
ABSTRACT Texture development and grain refinement of interstitial-free (IF) steel as a function o... more ABSTRACT Texture development and grain refinement of interstitial-free (IF) steel as a function of ideal simple shear or torsion was undertaken for up to 8 pressings, Route BC. Dominant texture components evolved after a single pass and remained correspondent for all subsequent passes. End-cycle (4 and 8 pass) orientation distribution functions (ODFs) showed an increased spread of contour levels and the re-appearance of texture components similar to the 0-pass condition. Rotation of torsion components away from their ideal pole figure (PF) orientations increased at mid-cycle and decreased to almost equivalent levels after end-cycle passes. This is attributed to the principle slip directions of BCC structures aligning with the shear direction.
One of the impediments to the uptake of wrought magnesium alloys has been their percei-ved poor f... more One of the impediments to the uptake of wrought magnesium alloys has been their percei-ved poor forming characteristics when compared to aluminium. Extrusion speeds for magnesium are typically quoted as between 2/3 and 1/3 that of aluminium [1], with a con-comitant ...
ABSTRACT Texture evolution during the microforming of severely deformed copper was studied by exp... more ABSTRACT Texture evolution during the microforming of severely deformed copper was studied by experimental measurements using X-ray and Electron Back-Scattered Diffraction techniques and by numerical simulation. The simulation includes the finite element analysis of micro-cup Swift tests on copper pre-deformed by different number of ECAP passes and polycrystal modelling of texture evolution. It was shown that FE simulations combined with a posteriori polycrystal plasticity modelling is an effective tool for the modelling of the texture development in the cup-drawing process. The obtained good agreement between the simulations and the measured texture development revealed that the rigid body rotations of the material during the cup test play a very important role in the texture evolution. Through-thickness variations of the texture were also observed both in experiments and simulations and are shown to be the result of the differences in the accumulated strains and the rigid body rotations across the cup wall.
ABSTRACT Interstitial-free steel and OFHC copper were subjected to 8 passes, route BC room temper... more ABSTRACT Interstitial-free steel and OFHC copper were subjected to 8 passes, route BC room temperature ECAE followed by cold-rolling up to 97.5% thickness reduction. Uniaxial tensile tests and Electron Back-Scattering Diffraction were used to characterise the evolution in mechanical properties, microstructure refinement and micro-texture. IF-steel showed continuous increase in strength whereas Cu returned reduced strength and a small gain in ductility at 97.5% reduction. In both metals substructure refinement was accompanied by an increase in high-angle boundary fraction, average misorientation and a slight increase in Σ3 boundaries. An evolution of crystallographic orientations from negative shear to predominantly cold-rolled textures after 95% and 97.5% reduction was observed in both metals.
ABSTRACT An extra-low-carbon steel was alloyed with 0.78 wt% Cr and subjected to three different ... more ABSTRACT An extra-low-carbon steel was alloyed with 0.78 wt% Cr and subjected to three different processing schedules involving: (i) warm rolling to 65% reduction at 640°C, (ii) warm rolling to 80% reduction at 580°C and (iii) warm rolling to 65% reduction at 640°C followed by cold rolling to 40% reduction. Increasing the severity of the deformation resulted in an increase in the number of grains containing in-grain shear bands. X-ray bulk texture analysis indicates that the γ-fibre intensity was slightly higher in the steel warm rolled at 580 °C than at 640°C and after cold rolling. Transmission electron microscopy and atom probe tomography revealed that Cr carbides were formed after all processing schedules. Carbon segregation to dislocations was also observed. Although the addition of 0.78 wt% Cr produced a volume fraction of carbides that was three orders of magnitude higher than those previously observed in 0.48 wt% Cr steels, a significant amount of solute Cr remained confined in the matrix and did not lead to any further depletion of the solute carbon.
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