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M Ferry - One of the best experts on this subject based on the ideXlab platform.
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time and temperature regime of continuous Grain Coarsening in an ecap processed al 0 1 wt sc alloy
Journal of Alloys and Compounds, 2012Co-Authors: A. Bommareddy, M.z. Quadir, M FerryAbstract:Abstract An equiaxed, submicron Grain size distribution was generated in an Al(0.1 wt.% Sc) alloy by processing through equal channel angular pressing followed by a low temperature pre-ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350, 400 and 450 °C for investigating the thermal stability of the deformation microstructure. It was found that up to 400 °C, the submicron Grain structure coarsens slowly and uniformly by a process of continuous recrystallization. Within this temperature range, the uniform dispersion of nano-sized Al 3 Sc particles generated by the pre-ageing treatment substantially hinders Grain Coarsening by Zener pinning of the (sub)Grain boundaries. At the higher annealing temperature of 450 °C, certain Grains were found to grow discontinuously thereby generating a mixed microstructure consisting of both fine and coarse Grains. The data in this study was combined with recent data for a higher solute Al(0.3 wt.% Sc) alloy for furthering our understanding of the time and temperature range in which this family of alloys is resistant to rapid, discontinuous Grain Coarsening (recrystallization).
Michael Ferry - One of the best experts on this subject based on the ideXlab platform.
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Time and temperature regime of continuous Grain Coarsening in an ECAP-processed Al(0.1 wt.% Sc) alloy
Journal of Alloys and Compounds, 2012Co-Authors: A. Bommareddy, M.z. Quadir, Michael FerryAbstract:Abstract An equiaxed, submicron Grain size distribution was generated in an Al(0.1 wt.% Sc) alloy by processing through equal channel angular pressing followed by a low temperature pre-ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350, 400 and 450 °C for investigating the thermal stability of the deformation microstructure. It was found that up to 400 °C, the submicron Grain structure coarsens slowly and uniformly by a process of continuous recrystallization. Within this temperature range, the uniform dispersion of nano-sized Al 3 Sc particles generated by the pre-ageing treatment substantially hinders Grain Coarsening by Zener pinning of the (sub)Grain boundaries. At the higher annealing temperature of 450 °C, certain Grains were found to grow discontinuously thereby generating a mixed microstructure consisting of both fine and coarse Grains. The data in this study was combined with recent data for a higher solute Al(0.3 wt.% Sc) alloy for furthering our understanding of the time and temperature range in which this family of alloys is resistant to rapid, discontinuous Grain Coarsening (recrystallization).
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Statistical Aspects of Grain Coarsening in a Fine Grained Al-Sc Alloy
Materials Science Forum, 2007Co-Authors: Michael Ferry, N. BurhanAbstract:A supersaturated Al-0.3 wt.% Sc alloy was cold deformed by ECAP to an equivalent von Mises strain of 9.2 then pre-aged at 350 °C to generate a fine-Grained alloy with an average Grain size of 1 μm. The microstructure was highly resistant to Grain Coarsening at temperatures up to 500 °C with a detailed statistical analysis showing that the initial Grain size distribution was very close to lognormal and, throughout annealing, remained lognormal and the normalized frequency distribution was time/temperature invariant despite a moderate broadening of the size distribution. This behaviour is largely similar to subGrain Coarsening during recovery and Grain growth after recrystallization. The homogeneous evolution of the microstructure during annealing, coupled with no appreciable change in texture, is also consistent with the advanced stages of continuous recrystallization.
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Spatial Uniformity of the Rate of Grain Coarsening in a Submicron Al-Sc Alloy Produced by Severe Plastic Deformation
Materials Science Forum, 2006Co-Authors: Michael FerryAbstract:The uniformity of Grain Coarsening throughout the microstructure of a submicron Grained particle-containing aluminium alloy has been investigated using high resolution EBSD. The alloy was processed by equal channel angular pressing (ECAP) and low temperature ageing to generate ~0.8
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Influence of fine particles on Grain Coarsening within an orientation gradient
Acta Materialia, 2005Co-Authors: Michael FerryAbstract:Abstract A simple model of Grain Coarsening is presented that takes into account the influence of both an orientation gradient within the microstructure and a dispersion of fine particles on the kinetics of Grain Coarsening. The model is used to illustrate the substantial influence of fine particles on Grain Coarsening whereby, in a particle-free system, Grains within a large orientation gradient grow rapidly whereas a system containing a large volume fraction of fine particles results in very limited Coarsening, despite the presence of the orientation gradient. The model is used in conjunction with the analysis of Grain Coarsening in some aluminium alloys where deformation was found to generate a range of microstructural inhomogeneities such as either deformation bands in hot deformed {1 0 0}〈0 0 1〉 Al–0.05%Si single crystals or a microstructure consisting of colonies of either low angle or high angle Grain boundaries in a severely strained particle-containing Al–0.2%Sc alloy. The simulations using the model are found to be in broad agreement with the experimental observations of Grain Coarsening in these alloy systems.
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Uniformity of Grain Coarsening in Submicron Grained Al-Sc Alloy Containing Local Variations in Texture
Materials Science Forum, 2005Co-Authors: Michael FerryAbstract:The effect of fine particles on the uniformity of Grain Coarsening in a submicron Grained Al-Sc alloy containing significant local variations in texture has been investigated using high resolution EBSD. The alloy was processed by severe plastic deformation and low temperature ageing to generate a fine-Grained (0.8 µm diameter) microstructure containing either a dispersion of nanosized Al3Sc particles or a particle-free matrix. The initial processing generated a uniform Grain size distribution, but the distribution of Grain orientations was inhomogeneous with the microstructure containing colonies of Grains consisting predominantly of either HAGBs or LAGBs with the latter possessing orientation gradients of up to 10 o/µm. Despite the marked differences in boundary character between these regions, the alloy undergoes slow and uniform Grain Coarsening during annealing at temperatures up to 500 oC with no marked change in the Grain size distribution, boundary distribution and texture. A model of Grain Coarsening that takes into account the influence of fine particles on the kinetics of Grain growth within an orientation gradient is outlined. The model predicts that a large volume fraction of fine particles (large f/r-value) tends to homogenize the overall rate of Grain Coarsening despite the presence of orientation gradients in the microstructure.
A. Bommareddy - One of the best experts on this subject based on the ideXlab platform.
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time and temperature regime of continuous Grain Coarsening in an ecap processed al 0 1 wt sc alloy
Journal of Alloys and Compounds, 2012Co-Authors: A. Bommareddy, M.z. Quadir, M FerryAbstract:Abstract An equiaxed, submicron Grain size distribution was generated in an Al(0.1 wt.% Sc) alloy by processing through equal channel angular pressing followed by a low temperature pre-ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350, 400 and 450 °C for investigating the thermal stability of the deformation microstructure. It was found that up to 400 °C, the submicron Grain structure coarsens slowly and uniformly by a process of continuous recrystallization. Within this temperature range, the uniform dispersion of nano-sized Al 3 Sc particles generated by the pre-ageing treatment substantially hinders Grain Coarsening by Zener pinning of the (sub)Grain boundaries. At the higher annealing temperature of 450 °C, certain Grains were found to grow discontinuously thereby generating a mixed microstructure consisting of both fine and coarse Grains. The data in this study was combined with recent data for a higher solute Al(0.3 wt.% Sc) alloy for furthering our understanding of the time and temperature range in which this family of alloys is resistant to rapid, discontinuous Grain Coarsening (recrystallization).
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Time and temperature regime of continuous Grain Coarsening in an ECAP-processed Al(0.1 wt.% Sc) alloy
Journal of Alloys and Compounds, 2012Co-Authors: A. Bommareddy, M.z. Quadir, Michael FerryAbstract:Abstract An equiaxed, submicron Grain size distribution was generated in an Al(0.1 wt.% Sc) alloy by processing through equal channel angular pressing followed by a low temperature pre-ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350, 400 and 450 °C for investigating the thermal stability of the deformation microstructure. It was found that up to 400 °C, the submicron Grain structure coarsens slowly and uniformly by a process of continuous recrystallization. Within this temperature range, the uniform dispersion of nano-sized Al 3 Sc particles generated by the pre-ageing treatment substantially hinders Grain Coarsening by Zener pinning of the (sub)Grain boundaries. At the higher annealing temperature of 450 °C, certain Grains were found to grow discontinuously thereby generating a mixed microstructure consisting of both fine and coarse Grains. The data in this study was combined with recent data for a higher solute Al(0.3 wt.% Sc) alloy for furthering our understanding of the time and temperature range in which this family of alloys is resistant to rapid, discontinuous Grain Coarsening (recrystallization).
M.z. Quadir - One of the best experts on this subject based on the ideXlab platform.
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time and temperature regime of continuous Grain Coarsening in an ecap processed al 0 1 wt sc alloy
Journal of Alloys and Compounds, 2012Co-Authors: A. Bommareddy, M.z. Quadir, M FerryAbstract:Abstract An equiaxed, submicron Grain size distribution was generated in an Al(0.1 wt.% Sc) alloy by processing through equal channel angular pressing followed by a low temperature pre-ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350, 400 and 450 °C for investigating the thermal stability of the deformation microstructure. It was found that up to 400 °C, the submicron Grain structure coarsens slowly and uniformly by a process of continuous recrystallization. Within this temperature range, the uniform dispersion of nano-sized Al 3 Sc particles generated by the pre-ageing treatment substantially hinders Grain Coarsening by Zener pinning of the (sub)Grain boundaries. At the higher annealing temperature of 450 °C, certain Grains were found to grow discontinuously thereby generating a mixed microstructure consisting of both fine and coarse Grains. The data in this study was combined with recent data for a higher solute Al(0.3 wt.% Sc) alloy for furthering our understanding of the time and temperature range in which this family of alloys is resistant to rapid, discontinuous Grain Coarsening (recrystallization).
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Time and temperature regime of continuous Grain Coarsening in an ECAP-processed Al(0.1 wt.% Sc) alloy
Journal of Alloys and Compounds, 2012Co-Authors: A. Bommareddy, M.z. Quadir, Michael FerryAbstract:Abstract An equiaxed, submicron Grain size distribution was generated in an Al(0.1 wt.% Sc) alloy by processing through equal channel angular pressing followed by a low temperature pre-ageing heat treatment. The alloy was subsequently annealed for various times at 300, 350, 400 and 450 °C for investigating the thermal stability of the deformation microstructure. It was found that up to 400 °C, the submicron Grain structure coarsens slowly and uniformly by a process of continuous recrystallization. Within this temperature range, the uniform dispersion of nano-sized Al 3 Sc particles generated by the pre-ageing treatment substantially hinders Grain Coarsening by Zener pinning of the (sub)Grain boundaries. At the higher annealing temperature of 450 °C, certain Grains were found to grow discontinuously thereby generating a mixed microstructure consisting of both fine and coarse Grains. The data in this study was combined with recent data for a higher solute Al(0.3 wt.% Sc) alloy for furthering our understanding of the time and temperature range in which this family of alloys is resistant to rapid, discontinuous Grain Coarsening (recrystallization).
M. Akiyama - One of the best experts on this subject based on the ideXlab platform.
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Grain Coarsening behaviour under small plastic strain in hot working of BS 304S31 stainless steel
Materials Science and Technology, 2002Co-Authors: Y. Neishi, M. AkiyamaAbstract:AbstractHot compression tests were conducted on an austenitic stainless steel, BS 304S31, to clarify the origin of the Grain Coarsening phenomenon that is observed for carbon steels deformed slightly at a high temperature. The Grain size was measured after hot compression testing, and the distribution was compared with that of the equivalent plastic strain ϵeq calculated using a rigid plastic finite element analysis technique. Similarly to carbon steels, a clear band zone was observed, although in a different region, in the plane difined by working temperature and ϵeq. The adoption of a material without a phase transformation has provided strong evidence supporting the hypothesis presented for carbon steels that the Grain Coarsening phenomenon is strain induced Grain growth in the austenite region. A peculiar, staggered Grain boundary was observed as the equivalent plastic strain approached the threshold value for the initiation of Grain Coarsening.
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Influence of temperature and plastic strain by cold working on Grain Coarsening behaviour of 304S31 stainless steel
Materials Science and Technology, 2002Co-Authors: M. Akiyama, Y. NeishiAbstract:Investigations were carried out to clarify the independence of two factors that govern the occurrence of the Grain Coarsening phenomenon: equivalent plastic strain and temperature. The material used was BS 304S31 stainless steel which exhibits no phase transformation. It was quickly heated after a cold compression test was carried out to evaluate separately the influences of equivalent plastic strain and temperature. It was found that, in the plane spanned by temperature and equivalent plastic strain given by cold working, there is a clear line at which initiation of Grain Coarsening occurs. This line exactly coincides with one obtained by a hot compression test, and it was concluded that equivalent plastic strain and temperature are two factors that govern the Grain Coarsening phenomenon. Additional experiments showed that a small amount of prestrain shortens the incubation time for the initiation of Grain Coarsening behaviour.
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A STUDY ON THE Grain Coarsening BEHAVIOUR IN HOT STEEL BAR ROLLING
2000Co-Authors: Y. Neishi, M. AkiyamaAbstract:This paper presents a successful example of numerical approaches for determining an optimum operational condition for hot steel rolling. In this study rigid-plastic finite element analyses were carried out on the Grain Coarsening behaviour. It has been qualitatively known in the field of hot steel rolling that Grain Coarsening phenomenon appears when a light reduction is applied. Surprisingly, however, no quantitative approach has been made so far for specifying the criterion for the occurrence of Grain Coarsening phenomenon, although existence of coarse Grain in the product is a fatal matter. An attempt was first made to observe the Grain Coarsening phenomenon by using a typical medium carbon steel, BSC45, and a hot deformation simulator. The specimens were subjected to microstructur e observation by optical microscopy, and comparison was made between the distribution of Grain size in the specimen and the equivalent plastic strain by an axi-symmetric rigid-plastic FE analysis using the code ELFEN developed at the University of Wales Swansea, U.K.. It was found that coarse Grain suddenly appears when the equivalent plastic strain reaches a certain value which depends upon the working temperature, and the dangerous zone where the coarse Grain is observed forms a band area in a plane defined by the working temperature and the equivalent plastic strain. An assumption was then derived from the observation of microstructure that the origin of the Grain Coarsening phenomenon can be attributed to the generation of coarse austenite Grain above the phase transformation temperature. Similar experiments were then carried out using low alloy steels and carbon steels other than BSC45 to find that the dangerous band zone for BSC45 applies to all the austenite-based steels. The validity of the new criterion was demonstrated by the rolling of a production bar mill.
