Achieving Both Powder Consolidation and Grain Refinement for Bulk Nanostructured Materials by Equal-Channel Angular Pressing

2007 ◽  
Vol 345-346 ◽  
pp. 173-176 ◽  
Author(s):  
Seung Chae Yoon ◽  
Do Minh Nghiep ◽  
Sun Ig Hong ◽  
Z. Horita ◽  
Hyoung Seop Kim
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Powder Metallurgy ◽  
Grain Refinement ◽  
Nanostructured Materials ◽  
Equal Channel Angular Pressing ◽  
Bottom Up ◽  
Powder Consolidation ◽  
Metallic Powders ◽  
Angular Pressing

Manufacturing bulk nanostructured materials with least grain growth from initial powders is challenging because of the bottle neck of bottom-up methods using the conventional powder metallurgy of compaction and sintering. In this study, bottom-up type powder metallurgy processing and top-down type SPD (Severe Plastic Deformation) approaches were combined in order to achieve both full density and grain refinement of metallic powders. ECAP (Equal-Channel Angular Pressing), one of the most promising processes in SPD, was used for the powder consolidation method. For understanding the ECAP process, investigating the powder density as well as internal stress, strain and strain rate distribution is crucial. We investigated the consolidation and plastic deformation of the metallic powders during ECAP using the finite element simulations. Almost independent behavior of powder densification in the entry channel and shear deformation in the main deformation zone was found by the finite element method in conjunction with a pressure dependent material yield model. Effects of processing parameters on densification and density distributions were investigated.

Equal Channel Angular Pressing of Metallic Powders for Nanostructured Materials

2006 ◽  
Vol 503-504 ◽  
pp. 221-226 ◽  
Author(s):  
Seung Chae Yoon ◽  
Hyoung Seop Kim
Keyword(s):  
Plastic Deformation ◽  
Nanostructured Materials ◽  
Equal Channel Angular Pressing ◽  
Powder Processing ◽  
Full Density ◽  
Bottom Up ◽  
Metallic Powders ◽  
Angular Pressing ◽  
Ecap Process ◽  
Strain And Strain Rate

In this study, bottom-up type powder processing and top-down type SPD (severe plastic deformation) approaches were combined in order to achieve both full density and grain refinement of metallic powders with least grain growth, which was considered as a bottle neck of the bottom-up method using the conventional powder metallurgy of compaction and sintering. ECAP (Equal channel angular pressing), one of the most promising method in SPD, was used for the powder consolidation. In the ECAP process of not only solid but also powder metals, knowledge of the density as well as internal stress, strain and strain rate distribution is important for understanding the process. We investigated the consolidation, plastic deformation and microstructure evolution behavior of the metallic powders during ECAP using experimental and theoretical methods. Almost independent behavior of powder densification in the entry channel and shear deformation in the main deformation zone was found by the finite element method in conjunction with a pressure dependent material yield model. It was found that high mechanical strength could be achieved effectively as a result of the well bonded powder contact surface during ECAP process of gas atomized Al-Si powders. The SPD processing of powders is a viable method to achieve both fully density and nanostructured materials.

Densification and Conolidation of Powders by Equal Channel Angular Pressing

2007 ◽  
Vol 534-536 ◽  
pp. 253-256 ◽  
Author(s):  
Seung Chae Yoon ◽  
Sun Ig Hong ◽  
Soon Hyung Hong ◽  
Hyoung Seop Kim
Keyword(s):  
Plastic Deformation ◽  
Equal Channel Angular Pressing ◽  
Powder Processing ◽  
Full Density ◽  
Bottom Up ◽  
Powder Consolidation ◽  
Metallic Powders ◽  
Angular Pressing ◽  
Ecap Process ◽  
Strain And Strain Rate

In this study, bottom-up type powder processing and top-down type SPD (severe plastic deformation) approaches were combined in order to achieve both full density and grain refinement of metallic powders with least grain growth, which is considered as a bottle neck of the bottom-up method that uses the conventional powder metallurgy of compaction and sintering. ECAP (Equal channel angular pressing), one of the most promising method in SPD, was used for the powder consolidation. In the ECAP process of not only solid but also powder metals, it is important to get a good understanding of the density as well as internal stress, strain and strain rate distribution. We investigated the consolidation, plastic deformation and microstructure evolution behavior of the metallic powders during ECAP using an experimental method. It was found that high mechanical strength could be achieved effectively due to the well bonded powder contact surface during ECAP process of gas atomized Al-Si powders. The experimental results show that SPD processing of powders is a viable method to achieve both fully density and nanostructured materials.

Equal Channel Angular Pressing of Al Alloy AA2219

2009 ◽  
Vol 67 ◽  
pp. 53-58
Author(s):  
V. Anil Kumar ◽  
M.K. Karthikeyan ◽  
Rohit Kumar Gupta ◽  
P. Ramkumar ◽  
P.P. Sinha
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
High Strength ◽  
Dark Field ◽  
Grain Structure ◽  
Al Alloy ◽  
Angular Pressing

Severe plastic deformation processes (SPD) are gaining importance as advanced materials processing techniques and hold immense potential in obtaining ultra fine-grained high strength materials. Among the SPD techniques, Equal channel angular pressing (ECAP) has its own merits to produce materials with ultra fine grains in bulk with better mechanical properties. The material deforms with high level of plastic strain inside the channel resulting in grain refinement of the output material with improvement in mechanical properties. A very viable die configuration was conceptualized and die was made with 1200 channel angle. Processing of 25 mm dia. of Al alloy AA2219 at room temperature was successfully carried out and grain refinement was observed. The mechanism of grain refinement has been studied using optical and transmission electron microscopy (TEM). It was observed that low energy dislocation structure (LEDS) forms concurrently with sub-grain structure due to dislocation rearrangements, which provide stability to the evolving sub-grain structure. Dislocation mobility is hindered by the presence of precipitates and / or intermetallic dispersoids present in the matrix and results in presence of dislocations in grain interiors. The pile up of dislocations at intermetallic dispersoids was confirmed from the dark field TEM micrographs. Present paper describes the experimental procedure and followed to attain severe plastic deformation through ECAP. Increase in hardness as well as refinement in the grain size after 5-passes have been discussed in light of extensive optical and TEM. The mechanisms of grain refinement to achieve nano-grained structure and strengthening accrued from the grain refinement through ECAP has been discussed.

Analysis of the Fundamental Mechanisms and Efficiency of the Deformation Methods of Nanostructuring

2008 ◽  
Vol 584-586 ◽  
pp. 29-34 ◽  
Author(s):  
Radik R. Mulyukov ◽  
Ayrat A. Nazarov ◽  
Renat M. Imayev
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Pressure ◽  
High Temperature ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Equal Channel Angular Pressing ◽  
Efficient Method ◽  
High Pressure Torsion ◽  
Angular Pressing

Deformation methods of nanostructuring (DMNs) of materials are proposed to classify into severe plastic deformation (SPD) and mild plastic deformation (MPD) methods according to fundamentally different low- and high-temperature grain refinement mechanisms they exploit. A general analysis of the fundamentals and nanostructuring efficiency of three most developed DMNs, high pressure torsion (HPT), equal-channel angular pressing (ECAP), and multiple isothermal forging (MIF) is done with a particular attention to ECAP and MIF. It is demonstrated that MIF is the most efficient method of DMNs allowing one to obtain the bulkiest nanostructured samples with enhanced mechanical properties.

A Study on the Aluminum Alloy AA1050 Severely Deformed by Non-Equal Channel Angular Pressing

2013 ◽  
Vol 651 ◽  
pp. 442-447 ◽  
Author(s):  
G.Y. Deng ◽  
C. Lu ◽  
L.H. Su ◽  
J.T. Li ◽  
H.T. Zhu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Equal Channel Angular Pressing ◽  
Deformation Behavior ◽  
Dead Zone ◽  
Equivalent Plastic Strain ◽  
Exit Channel ◽  
Outer Corner ◽  
Angular Pressing

In order to improve the efficiency of grain refinement, a study on the modified process (called Non-equal channel angular pressing) from the conventional equal channel angular pressing has been conducted. The deformation behavior of aluminum alloy AA1050 deformed by the Non-equal channel angular pressing which has a smaller width in the exit channel than the entry channel was examined based on the finite element simulations. The results revealed that a smaller ratio of dE and dI (dE/dI) leads to a larger equivalent plastic strain. It is not only beneficial to enhance the plastic deformation but also very helpful to get rid of the development of dead zone in the outer corner of die by decreasing the exit channel width by comparing with the conventional process.

Sign in / Sign up

Export Citation Format

Share Document