Developing High Strain Rate Superplasticity in Aluminum Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 2949-2954 ◽  
Author(s):  
Cheng Xu ◽  
Minoru Furukawa ◽  
Z. Horita ◽  
Terence G. Langdon
Keyword(s):  
Elevated Temperatures ◽  
High Strain ◽  
Superplastic Forming ◽  
Ultrafine Grain ◽  
Strain Rates ◽  
Cast Aluminum ◽  
Grain Sizes ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Materials Used

The conventional materials used in superplastic forming operations generally have grain sizes of ~2 µm or larger and they exhibit superplasticity at relatively low strain rates. Processing by equal-channel angular pressing (ECAP) produces materials having ultrafine-grain sizes, usually in the submicrometer range. If these ultrafine grains show reasonable stability at elevated temperatures, the alloys may exhibit a capability for achieving superplastic elongations at high strain rates. This paper examines the development of ultrafine-grained structures and superplastic ductilities in a spray-cast aluminum 7034 alloys through ECAP. The results show that ECAP is a very effective procedure for achieving grain refinement and superplasticity at rapid strain rates.

Achieving Superplasticity and Superplastic Forming through Severe Plastic Deformation

2000 ◽  
Vol 634 ◽  
Author(s):  
Minoru Furukawa ◽  
Zenji Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Elevated Temperatures ◽  
Superplastic Forming ◽  
Ultrafine Grain ◽  
Strain Rates ◽  
Grain Sizes ◽  
Angular Pressing ◽  
Large Bulk ◽  
Processing Procedure

ABSTRACTThe application of severe plastic deformation to metals provides a convenient procedure for achieving nanometer and submicrometer microstructures. Several different processing methods are available but Equal-Channel Angular Pressing (ECAP) is especially attractive because it provides an opportunity for preparing relatively large bulk samples. This paper describes the use of ECAP in preparing materials with ultrafine grain sizes and the subsequent properties of these materials at elevated temperatures. It is demonstrated that, provided precipitates are present to retain these small grain sizes at the high temperatures where diffusion is reasonably rapid, it is possible to achieve remarkably high superplastic elongations in the as-pressed materials and there is a potential for making use of this processing procedure to develop a superplastic forming capability at very rapid strain rates.

Advances in Superplasticity of Ultrafine-Grained Alloys: Recent Research and Development

2016 ◽  
Vol 838-839 ◽  
pp. 23-33 ◽  
Author(s):  
Ruslan Z. Valiev ◽  
Irina P. Semenova
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Superplastic Forming ◽  
Ultrafine Grain ◽  
Strain Rates ◽  
Unusual Behavior ◽  
Angular Pressing ◽  
Ti Alloys ◽  
Ultrafine Grained ◽  
New Applications

Recent studies have revealed that ultrafine-grained (UFG) metals and alloys produced by severe plastic deformation (SPD) can demonstrate extraordinary superplasticity at low temperatures and/or high strain rates. This work presents new results on superplasticity in several UFG Al and Ti alloys focusing on microstructural evolution and strain hardening, as well as the challenges of their application. Grain refinement in these alloys was accomplished using severe plastic deformation techniques, including new modifications of equal channel angular pressing (ECAP). Unusual behavior of UFG alloys originates both from the formation of ultrafine grain by SPD processing as well as the state of grain boundaries in these materials. It is established that superplastic deformation allowed not only to attain their efficient forming, but also to improve the ultrafine-grained structure and to obtain enhanced mechanical properties in the articles produced. The results demonstrate the possibilities of new applications of superplastic forming using bulk nanostructured materials.

Superplastic Behavior in Ultrafine-Grained Materials Produced by Equal-Channel Angular Pressing

2008 ◽  
Vol 579 ◽  
pp. 29-40 ◽  
Author(s):  
Cheng Xu ◽  
Megumi Kawasaki ◽  
Roberto B. Figueiredo ◽  
Zhi Chao Duan ◽  
Terence G. Langdon
Keyword(s):  
Equal Channel Angular Pressing ◽  
High Strain ◽  
Processing Method ◽  
Strain Rates ◽  
Bulk Materials ◽  
Superplastic Behavior ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials ◽  
Aluminum And Magnesium Alloys

Equal-channel angular pressing (ECAP) is a convenient processing method for refining the grain size of bulk materials to the submicrometer level. Metallic alloys processed by ECAP often exhibit excellent superplastic characteristics including superplasticity at high strain rates. This paper summarizes recent experiments designed to evaluate the occurrence of superplasticity in representative aluminum and magnesium alloys and in the Zn-22% Al eutectoid alloy.

Processing of Aluminium Alloys by Severe Plastic Deformation

2006 ◽  
Vol 519-521 ◽  
pp. 45-54 ◽  
Author(s):  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Elevated Temperatures ◽  
High Pressure Torsion ◽  
Simple Procedure ◽  
Superplastic Forming ◽  
High Strength ◽  
Ultrafine Grain ◽  
Grain Sizes

Processing through the application of severe plastic deformation (SPD) has become important over the last decade because it is now recognized that it provides a simple procedure for producing fully-dense bulk metals with grain sizes lying typically in the submicrometer range. There are two major procedures for SPD processing. First, equal-channel angular pressing (ECAP) refers to the repetitive pressing of a metal bar or rod through a die where the sample is constrained within a channel bent through an abrupt angle at, or close to, 90 degrees. Second, high-pressure torsion (HPT) refers to the procedure in which the sample, generally in the form of a thin disk, is subjected to a very high pressure and concurrent torsional straining. Both of these processes are capable of producing metallic alloys with ultrafine grain sizes and with a reasonable degree of homogeneity. Furthermore, the samples produced in this way may exhibit exceptional mechanical properties including high strength at ambient temperature through the Hall-Petch relationship and a potential superplastic forming capability at elevated temperatures. This paper reviews these two procedures and gives examples of the properties of aluminum alloys after SPD processing.

THE PROPERTIES OF BULK ULTRAFINE-GRAINED METALS PROCESSED THROUGH THE APPLICATION OF SEVERE PLASTIC DEFORMATION

2012 ◽  
Vol 05 ◽  
pp. 299-306
Author(s):  
TERENCE G. LANGDON
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Elevated Temperatures ◽  
High Pressure Torsion ◽  
Superplastic Forming ◽  
High Strength ◽  
Basic Principles ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Processing Techniques

Processing through the application of severe plastic deformation (SPD) provides a very attractive tool for the production of bulk ultrafine-grained materials. These materials typically have grain sizes in the submicrometer or nanometer ranges and they exhibit high strength at ambient temperature and, if the ultrafine grains are reasonably stable at elevated temperatures, they have a potential for use in superplastic forming operations. Several procedures are now available for applying SPD to metal samples but the most promising are Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT). This paper examines the basic principles of ECAP and HPT and describes some of the properties that may be achieved using these processing techniques.

Superplasticity of Ultrafine-Grained Aluminum Alloy Processed by ECAP and Warm Rolling

2007 ◽  
Vol 551-552 ◽  
pp. 13-20
Author(s):  
Rinat K. Islamgaliev ◽  
N.F. Yunusova ◽  
M.A. Bardinova ◽  
A.R. Kilmametov ◽  
Ruslan Valiev
Keyword(s):  
Aluminum Alloy ◽  
Room Temperature ◽  
High Strain ◽  
High Strength ◽  
Warm Rolling ◽  
Grain Structure ◽  
Strain Rates ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Equiaxed Grain

The ultrafine-grained (UFG) 1421 aluminum alloy processed by equal channel angular pressing (ECAP) has demonstrated enhanced superplasticity at low temperature and high strain rates. This UFG material was successfully rolled at temperatures of 330-370oC retaining small grain size and equiaxed grain structure. The microstructure of the UFG alloy subjected to warm rolling (WR) was studied, and the mechanical properties of the ECAP+WR samples with UFG structures were investigated. We have found that the rolled material exhibited not only the enhanced superplasticity, but also high strength at room temperature.

Effect of Mg Content on High Strain Rate Superplasticity of Al-Mg-Sc-Zr Alloys Subjected to Equal-Channel Angular Pressing

2012 ◽  
Vol 735 ◽  
pp. 265-270 ◽  
Author(s):  
Rustam Kaibyshev ◽  
Daria Zhemchuzhnikova ◽  
Anna Mogucheva
Keyword(s):  
Equal Channel Angular Pressing ◽  
High Strain ◽  
Tensile Tests ◽  
Chemical Compositions ◽  
Strain Rates ◽  
Grain Sizes ◽  
Angular Pressing ◽  
Mg Content ◽  
Very High ◽  
Zr Alloys

Aluminium alloys with a chemical compositions of Al–5.8%Mg–0.52%Mn–0.2%Sc–0.07%Zr–0.16%Fe-0.1%Si and Al-5.4%Mg-0.34%Mn-0.2%Sc-0.07%Zr-0.07%Fe-0.02Si (in weight %), denoted as 1570 and 1570C, respectively, were processed by equal-channel angular pressing (ECAP) at 300°C up to strain ε~12. Extensive grain refinement provided the formation of fully recrystallized structure with the average grain sizes of 0.7 and 0.6 μm, respectively. Tensile tests were carried out in the temperature interval 200–550oC at strain rates ranging from 10-4 to 10-1 s-1. Very high tensile elongations (>1000%) were achieved in the both alloys at T350oC and strain rates higher than 10-3 s-1.

Extending Creep and Superplasticity to Materials with Submicrometer Grain Sizes

2007 ◽  
Vol 345-346 ◽  
pp. 539-544
Author(s):  
Megumi Kawasaki ◽  
Cheng Xu ◽  
Z. Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloys ◽  
Severe Plastic Deformation ◽  
Flow Behavior ◽  
Ultrafine Grain ◽  
Grain Sizes ◽  
Large Samples ◽  
Angular Pressing ◽  
Recent Advances ◽  
Ultrafine Grained

The mechanisms of creep and superplasticity occurring in conventional large-grained materials are now understood reasonably well. However, very recent advances in the processing of theoretically-dense metals with submicrometer grain sizes have provided the opportunity to extend the understanding of flow behavior to include materials where the grains are exceptionally small. Using processing through the application of severe plastic deformation, as in procedures such as equal-channel angular pressing, it is now feasible to fabricate relatively large samples having ultrafine grain sizes in the submicrometer or nanometer range. This paper examines these recent advances and gives examples of the flow behavior in ultrafine-grained aluminum alloys.

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