Superplastic Flow and Micro-Mechanical Response of Ultrafine-Grained Materials

2018 ◽  
Vol 385 ◽  
pp. 9-14
Author(s):  
Megumi Kawasaki ◽  
Jae Il Jang ◽  
Terence G. Langdon
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Mechanical Response ◽  
High Pressure Torsion ◽  
Flow Behavior ◽  
Superplastic Flow ◽  
Al Alloy ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Superior Mechanical Properties

The bulk ultrafine-grained (UFG) materials usually show superior mechanical properties. Since the occurrence of superplastic flow generally requires a grain size smaller than ~10 μm, it is anticipated that materials processed by severe plastic deformation (SPD) will exhibit superplastic ductilities when pulled in tension at elevated temperatures. Recent advances in the processing of UFG metals have provided an opportunity to extend the understanding of superplastic flow behavior to include UFG materials with submicrometer grain sizes. Recent studies showed the UFG materials demonstrated the development of plasticity in micro-mechanical response at room temperature by the significant changes in microstructure attributed to high-pressure torsion (HPT). Accordingly, this study summarizes recent results on excellent ductility and plasticity in a UFG Zn-22% Al alloy. Specifically, the alloy demonstrated the occurrence of exceptional superplastic flow at high temperature after equal-channel angular pressing and HPT and excellent room temperature plasticity of the alloy after HPT where the plasticity was evaluated by the nanoindentation technique. The significance of purity of the alloy is also considered for enhancing the ductility at room temperature.

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.

The Effect of Ultrafine-Grained Structure of Al-30Zn on the Shape Forming Ability at Sheet Metal Forming

2018 ◽  
Vol 385 ◽  
pp. 228-233
Author(s):  
Elena V. Bobruk ◽  
Denis G. Tyulenev ◽  
Oleg V. Golubev ◽  
Maxim Y. Murashkin
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Aluminum Matrix ◽  
Test Method ◽  
Coarse Grained ◽  
Angular Pressing ◽  
Ultrafine Grained

High pressure torsion (HPT) and equal channel angular pressing in parallel channels (ECAP-PC) at room temperature are used to form homogeneous ultrafine-grained (UFG) structure with a grain size of the aluminum matrix of 350 and 700 nm, respectively, in Al-30Zn (wt. %) specimens. The UFG samples with special geometry produced from the specimens processed by SPD techniques were subjected to sphere-shaped dimple extrusion testing (via the Erikson test method) and bended plate extrusion to determine the material formability during cold sheet metal forming. The same tests were performed on the material with coarse-grained (CG) structure for the sake of comparison. The obtained results are discussed.

The Flow Behavior of Ultrafine-Grained Materials

2014 ◽  
Vol 1013 ◽  
pp. 7-14
Author(s):  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
High Pressure Torsion ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
High Strength ◽  
Flow Properties ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Small Grains ◽  
Ultrafine Grained Materials

Processing through the application of severe plastic deformation (SPD) leads to very significant grain refinement with grains that are typically in the submicrometer or even the nanometer range. These ultrafine-grained (UFG) materials provide an opportunity for achieving exceptional flow properties including high strength at ambient temperature and, if the very small grains are reasonably stable, superplastic elongations at high testing temperatures. These flow characteristics are examined for materials processed using the two SPD procedures of equal-channel angular pressing (ECAP) and high-pressure torsion (HPT).

Mechanical Properties of Ultrafine-Grained Al Alloy for Engineering Machinery

2012 ◽  
Vol 629 ◽  
pp. 198-202 ◽  
Author(s):  
Ping Yang ◽  
Kai Huai Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Equal Channel Angular Pressing ◽  
Room Temperature ◽  
Al Alloy ◽  
Fracture Modes ◽  
Annealed State ◽  
Angular Pressing ◽  
Ultrafine Grained

Three groups of commercial 1050 Al alloy were subjected to equal channel angular pressing (ECAP) at room temperature using route A, route C and route Bc, respectively. Mechanical properties and fracture modes of as-annealed and ECAPed samples were investigated. The microhardness of 1050 Al fabricated by ECAP increases by a factor of about 1.5 compared to the as-annealed state. The ultimate tensile strength (UTS) increases significantly after ECAP, while the elongation decreases. But they are strongly dependence on the number of ECAP passes and the pressing route. The UTS and elongation of the samples processed by route Bc are best, consequently, the static toughness U of the samples is enhanced. Besides, all specimens subjected to ECAP deformation failed in a ductile manner.

Development of Complex Methods, Combining Thermal Treatment with Severe Plastic Deformation, for Processing of High-Strength Nanostructured Cu-1%Cr-0.7%Al Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 515-520 ◽  
Author(s):  
Igor V. Alexandrov ◽  
V.V. Latysh ◽  
Sun Ig Hong ◽  
S.N. Faizova ◽  
V.M. Polovnikov
Keyword(s):  
Plastic Deformation ◽  
Thermal Treatment ◽  
Severe Plastic Deformation ◽  
High Pressure Torsion ◽  
High Strength ◽  
Al Alloy ◽  
Thermal Treatments ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Complex Methods

The current work presents new results of investigation of properties and structure of nanocrystalline and submicrocrystalline Cu-1%Cr-0.7%Al alloy. Two severe plastic deformation (SPD) techniques were applied to refine the structure: high pressure torsion and equal-channel angular pressing (ECAP). The first technique was applied to conduct preliminary studies of the alloy different thermal treatments as before SPD as well as after it. A new technological thermomechanical technique for processing of bulk billets of Cu-1%Cr-0.7%Al alloy possessing an ultrafine grained structure was developed on the basis of the obtained results. This technique comprises a combination of ECAP and other deformational processes with the thermal treatment. High values of the tensile strength and yield stress - 700 MPa and 16% accordingly – have been obtained as a result of such treatment, whereas these values after conventional treatment consisted 450 MPa and 20% respectively.

Description of the Superplastic Flow Process by Deformation Mechanism Maps in Ultrafine-Grained Materials

2016 ◽  
Vol 838-839 ◽  
pp. 51-58 ◽  
Author(s):  
Megumi Kawasaki ◽  
Terence G. Langdon
Keyword(s):  
Deformation Mechanism ◽  
Elevated Temperatures ◽  
High Pressure Torsion ◽  
Processing Technique ◽  
Superplastic Flow ◽  
Coarse Grained ◽  
Ultrafine Grain ◽  
Flow Process ◽  
Ultrafine Grained ◽  
Wide Range

The synthesis of ultrafine-grained (UFG) materials is very attractive because small grains lead to excellent creep properties including superplastic ductility at elevated temperatures. Severe plastic deformation (SPD) is an attractive processing technique for refining microstructures of metallic materials to have ultrafine grain sizes within the submicrometer to even the nanometer level. Among the SPD techniques, most effective processing is conducted through equal-channel angular pressing (ECAP) and high-pressure torsion (HPT) and there are numerous reports demonstrating the improved tensile properties at elevated temperature. This report demonstrates recent results on superplasticity in metals after ECAP and HPT. Moreover, superplastic flow of the UFG materials is evaluated by using flow mechanisms developed earlier for coarse-grained materials and depicted by plotting deformation mechanism maps which provide excellent visual representations of flow properties over a wide range of testing conditions.

Enhanced Ductility in Ultrafine-Grained Al Alloys Produced by SPD Techniques

2009 ◽  
Vol 633-634 ◽  
pp. 321-332 ◽  
Author(s):  
Ruslan Valiev ◽  
Maxim Yu. Murashkin ◽  
Boris B. Straumal
Keyword(s):  
Room Temperature ◽  
High Pressure Torsion ◽  
High Strength ◽  
Al 6061 ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Processing Regimes ◽  
Zn Alloy ◽  
Strength And Ductility

In this work ultrafine-grained (UFG) structure was successfully produced in the commercial Al 6061 and Al-30%Zn alloys using new modifications of two severe plastic deformation (SPD) techniques, namely equal channel angular pressing (ECAP) with parallel channels (PC) and high pressure torsion (HPT) with enhanced load. Variation of SPD processing regimes made it possible not only to perform strong grain refinement but also to modify the phase composition through the formation of grain boundary (GB) segregations and precipitations. This enabled to achieve a unique combination of high strength and ductility in the Al 6061 alloy and demonstrate super-ductility in the Al-30%Zn alloy, when elongation to failure exceeded 150% at room temperature.

scholarly journals Влияние дополнительной интенсивной пластической деформации при повышенных температурах на микроструктуру и функциональные свойства ультрамелкозернистого сплава Al-0.4Zr

2019 ◽  
Vol 61 (12) ◽  
pp. 2477
Author(s):  
Т.С. Орлова ◽  
Т.А. Латынина ◽  
М.Ю. Мурашкин ◽  
В.У. Казыханов
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Electron Scattering ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
High Pressure Torsion ◽  
Secondary Phase ◽  
Microstructural Parameters ◽  
Ultrafine Grained ◽  
Hardening Mechanisms

The effect of high pressure torsion (HPT) at elevated temperatures of 230 and 280°C on the microstructure, mechanical properties and electrical conductivity of ultrafine-grained (UFG) Al-0.4Zr alloy was studied. The initial UFG structure in the material of the study was preliminarily formed by HPT-processing at room temperature. It was shown that the additional deformation of the UFG Al-0.4Zr alloy at elevated temperatures leads to a simultaneous significant increase in strength from 140 to 230-280 MPa and electrical conductivity from ~ 47.5% to 52-54% IACS. The obtained results are compared with the effect of annealing at the same temperatures on the microstructure and properties of the UFG Al-0.4Zr alloy. It was found that, compared with annealing, severe plastic deformation at the same temperature leads to more efficient formation of nanoscale precipitates of the Al3Zr secondary phase and, consequently, to a larger decrease in the Zr concentration in the solid solution, which provides a significant increase in electrical conductivity. Based on the obtained microstructural parameters, the contributions of various hardening mechanisms to the total hardening and electron scattering mechanisms to electrical resistivity are estimated. Comparison of the theoretical estimates with the experimental results indicates that the hardening in the UFG structure of the Al-0.4Zr alloy caused by additional SPD at elevated temperatures cannot be described only by the action of hardening mechanisms traditional for UFG materials. Possible reasons for the colossal hardening obtained are discussed.

Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations

2006 ◽  
Vol 503-504 ◽  
pp. 31-36 ◽  
Author(s):  
Johannes Mueller ◽  
Karsten Durst ◽  
Dorothea Amberger ◽  
Matthias Göken
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Fcc Metals ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Indentation Strain

The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.

scholarly journals COMPRESSION OF ECAPED TITANIUM MICRO-PILLARS FOR TWO PRINCIPAL ORIENTATIONS

2020 ◽  
Vol 27 ◽  
pp. 1-5
Author(s):  
David Vokoun ◽  
Jan Maňák ◽  
Karel Tesař ◽  
Stanislav Habr
Keyword(s):  
Room Temperature ◽  
Focused Ion Beam ◽  
Mechanical Response ◽  
Thermomechanical Processing ◽  
Ion Beam ◽  
Orientation Dependence ◽  
Material Strength ◽  
Angular Pressing ◽  
Macro Scale ◽  
Micro Pillars

The thermomechanical processing by equal-channel angular pressing (ECAP) is used for certain metals and alloys in order to make their structure fine and to increase material strength. In the previous study done at our institute, grade 2 titanium was successfully processed using four consecutive route A passes via a 90 ° ECAP die with high backpressure at room temperature. Orientation dependence of compressive and tensile loading of ECAPed titanium samples was demonstrated at macro-scale. However, scarce attention has been paid so far to the mechanical behavior of ECAPed titanium samples at micro-scale. In the present study, compression experiments on titanium micropillars, fabricated using focused ion beam, are carried out for two main directions in respect to preceding ECAP pressing (insert and extrusion directions). The purpose of this study is to discuss the orientation dependence of mechanical response during compression of the as-ECAPed titanium micro-pillars.

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