scholarly journals Molecular Dynamics Study on Grain Refinement Process of α-Iron by Equal Channel Angular Pressing under Quasi 3-Dimensional Condition

2006 ◽  
Vol 55 (7) ◽  
pp. 693-699 ◽  
Author(s):  
Ryosuke MATSUMOTO ◽  
Toshio HAYASHIDA ◽  
Michihiko NAKAGAKI
Keyword(s):  
Molecular Dynamics ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
3 Dimensional ◽  
Angular Pressing ◽  
Refinement Process ◽  
Dimensional Condition

Grain Refinement Mechanisms Oterative during Equal Channel Angular Pressing of Aluminium

2011 ◽  
Vol 702-703 ◽  
pp. 135-138
Author(s):  
Rampada Manna ◽  
N.K. Mukhopadhyay ◽  
G.V.S. Sastry
Keyword(s):  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Room Temperature ◽  
Lattice Rotation ◽  
Recrystallization Process ◽  
Continuous Dynamic Recrystallization ◽  
Angular Pressing ◽  
Subgrain Formation ◽  
Refinement Process ◽  
Continuous Dynamic

Grain refinement of aluminum deformed by equal channel angular pressing is strongly dependent on the amount of strain. The refinement process at low to high strain level involves elongation of the existing grains by shear deformation, their subdivision into bands and subgrain formation within bands, intersection of the bands during subsequent passes and finally conversion of the subgrains to grains by continuous dynamic recrystallization process. At room temperature the conversion of subgrains to grains takes place by progressive lattice rotation.

Molecular Dynamics Analysis on Initial Texture and Processing Route Influences on Grain Refinement Behavior of α-Fe by Equal Channel Angular Pressing

2007 ◽  
Vol 340-341 ◽  
pp. 967-972
Author(s):  
Ryosuke Matsumoto ◽  
Toshio Hayashida ◽  
Michihiko Nakagaki
Keyword(s):  
Molecular Dynamics ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Simple Shear ◽  
Stress Component ◽  
High Yield ◽  
Processing Route ◽  
Shear Direction ◽  
Angular Pressing ◽  
Initial Texture

Fine-grained polycrystalline metals have a very high yield stress and excellent workability. Hence, numerous researchers are trying to develop an efficient process to obtain such materials. Our goal is to develop an efficient severe plastic deformation (SPD) process through investigating grain-refinement mechanisms in Equal Channel Angular Pressing (ECAP). In this paper, a series of molecular dynamics (MD) simulations of severe simple-shear deformations, which are ideally equivalent to SPD applied by typical ECAP processing routes, is performed using three-dimensional models that are thin and have a square shape with a periodic-boundary condition. We analyze the influences of the processing route and initial texture on the microstructural evolution. It is shown that twinning deformations are dominant under the calculated conditions, and that the structural evolution is notably affected by the relationship between the applied simple-shear direction and the characteristic crystal orientation, which can easily cause a twinning deformation. We conclude that Route A, without a rotation of the billet between processes, is the most efficient route. This is because twinning deformations along the simple-shear direction interact with the twin boundaries developed by the stress-component conjugate to the simple-shear. Furthermore, we demonstrate that the influence of the initial texture difference remains in force during multiple processes that have the same sliding plane.

Influence of Stacking Fault Energy on the Microstructures and Grain Refinement in the Cu-Al Alloys during Equal-Channel Angular Pressing

2010 ◽  
Vol 667-669 ◽  
pp. 379-384 ◽  
Author(s):  
X.H. An ◽  
Shi Ding Wu ◽  
Z.F. Zhang
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Al Alloys ◽  
Stacking Fault ◽  
High Recovery ◽  
Angular Pressing ◽  
High Recovery Rate ◽  
Refinement Mechanism ◽  
Stacking Fault Energies

The microstructural evolution and grain refinement of Cu-Al alloys with different stacking fault energies (SFEs) processed by equal-channel angular pressing (ECAP) were investigated. The grain refinement mechanism was gradually transformed from dislocation subdivision to twin fragmentation with tailoring the SFE of Cu-Al alloys. Concurrent with the transition of grain refinement mechanism, the grain size can be refined into from ultrafine region (1 m~100 nm) to the nanoscale (<100 nm) and then it is found that the minimum equilibrium grain size decreases in a roughly linear way with lowering the SFE. Moreover, in combination with the previous results, it is proposed that the formation of a uniform ultrafine microstructure can be formed more readily in the materials with high SFE due to their high recovery rate of dislocations and in the materials with low SFE due to the easy formation of a homogeneously-twinned microstructure.

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