Severe Plastic Deformation under High Pressure for Production of Superplastic Materials

2016 ◽  
Vol 838-839 ◽  
pp. 287-293 ◽  
Author(s):  
Zenji Horita
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
High Pressure Torsion ◽  
High Strength ◽  
Al Alloys ◽  
Strain Rates ◽  
Ti Alloys

Grain refinement is an important prerequisite for advent of superplasticity. In particular, as the grain size is smaller, the superplasticity appears at higher strain rates and lower temperatures. Severe plastic deformation (SPD) is a useful process for achieving significant grain refinement. This presentation shows that applicability of the SPD process is enhanced when it is operated under high pressure through high-pressure torsion (HPT) and high-pressure sliding (HPS). It is demonstrated that commercially available conventional alloys but less ductile alloys such as Mg alloys, age-hardenable high-strength Al alloys (A2024, A7075) and Ti alloys become superplastic after processing by HPT or HPS.

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.

Thermo- and Deformation Induced Martensitic Transformations in Binary TiNi-Based Alloys Subjected to Severe Plastic Deformation

2013 ◽  
Vol 738-739 ◽  
pp. 530-534 ◽  
Author(s):  
Natalia N. Kuranova ◽  
Vladimir V. Makarov ◽  
Vladimir G. Pushin ◽  
Alexey N. Uksusnikov
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Amorphous State ◽  
Cold Drawing ◽  
Martensitic Transformations ◽  
Subsequent Annealing ◽  
Structure And Phase Transformations

Results of investigations of structure and phase transformations and properties of the TiNi-based alloys with a shape memory effect (SME) after severe plastic deformation (SPD) by cold rolling, cold drawing, high pressure torsion and subsequent annealing are reported. It is found that the baroelastic effects related to the highly reversible martensitic transformations can occur in alloys, subjected to high pressure. The evolution of fine structure of the alloys into nanocrystalline and then amorphous state during SPD and after subsequent annealing have been studied. The effect of grain size on the martensitic transformations and properties of the alloys is discussed.

Comparison between FEM and Experimental Results in the Upsetting of Nano-Structured Materials

2012 ◽  
Vol 713 ◽  
pp. 31-36 ◽  
Author(s):  
C.J. Luis-Pérez ◽  
Ignacio Puertas ◽  
Daniel Salcedo ◽  
Javier León ◽  
Ivan Pérez
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Equal Channel Angular Extrusion ◽  
High Pressure Torsion ◽  
Experimental Results ◽  
Structured Materials ◽  
Angular Extrusion ◽  
Deformation Processes

Over recent years, some severe plastic deformation processes have been developed with the aim of obtaining a material with sub-micrometric or even nanometric grain size, such as: ECAE (Equal channel angular extrusion) and HPT (High pressure torsion) among many others. The main aim of this present study is to analyse the upsetting of the 5083 Al-Mg-Mn alloy, which had been previously deformed by ECAE. Different processing temperatures will be used and the final properties of the resulting material will be determined.

Evolution of Microstructure and Microhardness in Ti-15Mo β-Ti Alloy Prepared by High Pressure Torsion

2016 ◽  
Vol 879 ◽  
pp. 2555-2560 ◽  
Author(s):  
Kristína Václavová ◽  
Josef Stráský ◽  
Jozef Veselý ◽  
Svetlana Gatina ◽  
Veronika Polyakova ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Dislocation Density ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
Positron Annihilation Spectroscopy ◽  
Equivalent Strain ◽  
Ti Alloys ◽  
Evolution Of Microstructure ◽  
Metastable Beta

The main aim of this study is to analyze the effect of the severe plastic deformation (SPD) on the mechanical properties and defect structure of metastable beta Ti alloys. Experiments were performed on two different β-Ti alloys: Ti-15Mo and Ti-6.8Mo-4.5Fe-1.5Al which were subjected to severe plastic deformation (SPD) by high pressure torsion (HPT). The increase of hardness with increasing equivalent strain was determined by microhardness mapping. Dislocation density was studied by advanced techniques of positron annihilation spectroscopy (PAS). Microhardness and dislocation density increases with increasing equivalent strain inserted by severe plastic deformation.

Developing the Technique of Severe Plastic Deformation Processing through High-Pressure Torsion

2010 ◽  
Vol 667-669 ◽  
pp. 397-402 ◽  
Author(s):  
Megumi Kawasaki ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
High Pressure Torsion ◽  
Severe Plastic Deformation Processing ◽  
Average Grain Size ◽  
High Purity Aluminum ◽  
Sample Characteristics ◽  
Nanoscale Range

The processing of metals through the application of severe plastic deformation provides the potential for achieving exceptional grain refinement in bulk solids. Several SPD methods are now available but processing by high-pressure torsion (HPT) has attracted much attention over the last five years. Numerous reports are now available describing the application of HPT to a range of pure metals and simple alloys and excellent grain refinement were achieved using this process with the average grain size often reduced to the nanoscale range. However, in order to make this technique more practical, the nature of the sample characteristics immediately after conventional HPT must be considered in order to understand the fundamental principles of HPT processing. This report examines the procedure with special emphasis on the evolution in hardness homogeneity in both high-purity aluminum and a Zn-22% Al eutectoid alloy processed by HPT.

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.

Deformation Mechanisms and Ductility of Nanostructured Al Alloys

2004 ◽  
Vol 821 ◽  
Author(s):  
Bing Q. Han ◽  
Farghalli A. Mohamed ◽  
Enrique J. Lavernia
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Aluminum Alloys ◽  
Severe Plastic Deformation ◽  
Work Hardening ◽  
Tensile Ductility ◽  
High Strength ◽  
Al Alloys ◽  
Deformation Mechanisms ◽  
Coarse Grains

AbstractLow tensile ductility is one of the critical challenges facing the science and technology of nanostructured materials. As an example, despite the fact that high strength is frequently observed in bulk nanostructured Al alloys, ductility and work hardening are often observed to decrease with decreasing grain size. In the present study, the tensile ductility of bulk nanostructured aluminum alloys processed via severe plastic deformation and consolidation of mechanically milled powders is analyzed. Adding coarse grains to the nanostructured matrix is proposed as an approach to improve ductility.

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