Mechanism of Low-Temperature Superplastic Deformation in Aluminum Alloys Containing a Dispersion of Nanoscale Al3(Sc,Zr) Particles

2016 ◽  
Vol 838-839 ◽  
pp. 150-156
Author(s):  
Rustam Kaibyshev
Keyword(s):  
Low Temperature ◽  
Strain Rate ◽  
Equal Channel Angular Extrusion ◽  
Rate Sensitivity ◽  
Sensitivity Coefficient ◽  
Superplastic Behavior ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
The Difference ◽  
Average Size

The ultrafine grained (UFG) structure with an average size of ∼0.8 μm was produced in an Al-Li-Mg-Sc alloy by equal-channel angular extrusion (ECAE) at 325oC with a total strain of ~16. Superplastic behavior was examined in the temperature range 150-250oC at strain rates ranging from 10-5 to 10-2 s-1. A maximum elongation-to-failure of 440% was recorded at 175oC (~0.5 Tm, where Tm is the melting point) and a strain rate of 2.8×10-5 s-1 with the corresponded strain rate sensitivity coefficient of 0.32. Mechanisms of low-temperature superplasticity (LTSP) and high-strain-rate superplasticity (HTSP) are essentially the same. The difference between superplastic behaviors at low and high temperatures is attributed to applied stress.

Low-Temperature Superplasticity in an Al-Mg-Sc Alloy Processed by ECAP

2016 ◽  
Vol 838-839 ◽  
pp. 422-427 ◽  
Author(s):  
Diana Yuzbekova ◽  
Anna Mogucheva ◽  
Rustam Kaibyshev
Keyword(s):  
Strain Rate ◽  
Rate Sensitivity ◽  
Sensitivity Coefficient ◽  
Strain Rates ◽  
Maximum Elongation ◽  
Superplastic Behavior ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Average Size

The ultrafine grained structure of an AA5024 with an average size of ∼0.7 μm was produced by equal-channel angular pressing (ECAP) at 300°C with a total strain of ~12. Superplastic behavior of this alloy was examined in the temperature interval 175 - 300°C at strain rates ranging from 10-4 to 10-1 s-1. The maximum elongation-to-failure of ~1200% with the corresponding strain rate sensitivity coefficient, m, of ∼0.49 was attained at a temperature of 275°C and a strain rate of 5.6×10–3s–1. At 175°C (~0.53Tm, where Tm is the melting point), the elongation-to-failure of ~370% with the m value of ~0.3 was found at ε̇=1.4×10–4 s–1.

Low-Temperature Superplasticity in an Al–Mg–Mn Alloy Subjected to ECAP and Subsequent Isothermal Rolling

2012 ◽  
Vol 735 ◽  
pp. 347-352
Author(s):  
Ilya Nikulin ◽  
Alla Kipelova ◽  
Rustam Kaibyshev
Keyword(s):  
Low Temperature ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
Sensitivity Coefficient ◽  
Angular Pressing ◽  
Elongation To Failure ◽  
Fine Grained Structure ◽  
Superplastic Properties ◽  
Average Size

An ultra-fine grained structure with an average size of ~ 1 μm was produced in a commercial Al–5.4%Mg–0.5%Mn–0.1%Zr–0.12%Si–0.014%Fe alloy by hot equal-channel angular pressing (ECAP) followed by isothermal rolling (IR). It was found that in the strain rate interval from 5.6×10-4to 2.8×10-2s-1the alloy exhibits a low-temperature superplasticity with elongation-to-failure exceeding 400% and the strain rate sensitivity coefficient of ~0.3. The highest elongation-to-failure of ~ 620% appeared at a temperature of ~ 275°C and an initial strain rate of ~ 5.6×10-3s-1. The relationship between superplastic properties and microstructural evolution of the examined alloy is discussed.

Superplastic Behavior of Friction-Stir Welded Joints of an Al-Mg-Sc Alloy with Ultrafine-Grained Microstructure

2016 ◽  
Vol 838-839 ◽  
pp. 338-343 ◽  
Author(s):  
Sergey Malopheyev ◽  
Sergey Mironov ◽  
Igor Vysotskiy ◽  
Rustam Kaibyshev
Keyword(s):  
Strain Rate ◽  
True Strain ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
Sensitivity Coefficient ◽  
Friction Stir ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Superplastic Properties

The commercial Al-5.4Mg-0.2Sc-0.1Zr alloy was subjected to equal-channel angular pressing at 300°C to a true strain ~12 followed by cold rolling to a total thickness reduction of 80%. The ultrafine-grained sheets were joined by friction stir welding (FSW). To evaluate superplastic properties of the weldments, the tensile samples including all of the characteristic FSW microstructural zones were machined perpendicular to the welding direction and pulled up to failure in the temperature range of 400 to 500°C and at strain rates of 2.8×10-4 s-1 to 5.6×10-1 s-1. The friction-stir welded material exhibited excellent superplastic properties. The highest elongation-to-failure of ~1370% was recorded at a temperature of ~450°C and an initial strain rate of 5.6×10-2 s-1, where the strain rate sensitivity coefficient was about 0.64. The relationship between superplastic ductility and microstructure is discussed.

Superplasticity of AlCoCrCuFeNi High Entropy Alloy

2012 ◽  
Vol 735 ◽  
pp. 146-151 ◽  
Author(s):  
Andrey V. Kuznetsov ◽  
Dmitry G. Shaisultanov ◽  
Nikita Stepanov ◽  
Gennady A. Salishchev ◽  
Oleg N. Senkov
Keyword(s):  
Particle Size ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
Tensile Ductility ◽  
Rate Sensitivity ◽  
Particle Growth ◽  
High Entropy Alloy ◽  
Superplastic Behavior ◽  
High Entropy ◽  
Elongation To Failure

An AlCoCrCuFeNi high entropy alloy was multiaxially isothermally forged at 950°C to produce a fine equiaxed structure with the average grain/particle size of ~1.5 µm. The forged alloy exhibited superplastic behavior in the temperature range of 800-1000°C. For example, during deformation at a strain rate of 10-3 s-1, tensile ductility increased from 400% to 860% when the temperature increased from 800°C to 1000°C. An increase in strain rate from 10-4 to 10-2 s-1 at T = 1000°C did not affect ductility: elongation to failure was about 800%. The strain rate sensitivity of the flow stress was rather high, m = 0.6, which is typical to the superplastic behavior. The equiaxed morphology of grains and particles retained after the superplastic deformation, although some grain/particle growth was observed.

Effect of Rolling on Superplastic Behavior of an Al-Mg-Sc Alloy with Ultrafine-Grained Structure

2016 ◽  
Vol 838-839 ◽  
pp. 416-421 ◽  
Author(s):  
Andrii Dubyna ◽  
Sergey Malopheyev ◽  
Rustam Kaibyshev
Keyword(s):  
Cold Rolling ◽  
Strain Rate ◽  
Rolling Direction ◽  
Initial Strain Rate ◽  
Warm Rolling ◽  
Initial Strain ◽  
Superplastic Behavior ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Superplastic Properties

The superplastic behavior of a commercial aluminum alloy denoted as 1570 Al with a chemical composition of Al-6%Mg-0.5%Mn-0.2%Sc-0.07%Zr (in wt. %) and ultrafine-grained (UFG) structure produced by equal channel angular pressing at 300°C to a true strain ~12 was studied after final cold or warm rolling. The tensile specimens were machined along rolling direction and pulled up to failure in the temperature range of 250 to 500°C at strain rates ranging from 10-4 s-1 to 10-1 s-1. The specimens produced by warm or cold rolling exhibit different superplastic behavior. The material subjected to warm rolling exhibits excellent superplastic properties; the highest elongation-to-failure of ~1970% was recorded at a temperature of ~450°C and an initial strain rate of 1.4×10-1 s-1. On the other hand, the material subjected to cold rolling demonstrates moderate superplastic properties; the highest elongation-to-failure of ~755% appears at a temperature of ~300°C and an initial strain rate of 1.4×10-2 s-1.

Superplasticity of an AA2519 Aluminum Alloy

2016 ◽  
Vol 838-839 ◽  
pp. 278-284
Author(s):  
Ivan Zuiko ◽  
Marat Gazizov ◽  
Rustam Kaibyshev
Keyword(s):  
Strain Rate ◽  
Thermomechanical Processing ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
Tensile Tests ◽  
Sensitivity Coefficient ◽  
Initial Strain ◽  
Strain Rates ◽  
Average Grain Size ◽  
Elongation To Failure

A commercial AA2519 alloy with a chemical composition of Al-5.64Cu-0.33Mn-0.23Mg-0.15Zr (in wt. %) was subjected to two-step thermomechanical processing (TMP) providing the formation of fully recrystallized structure with an average grain size of ~7 mm in 3 mm thin sheets. Superplastic tensile tests were performed in the temperature interval 450-535°C and initial strain rates ranging from ~2.8 x 10-4 to ~6.0 x 10-1 s-1. The highest elongation-to-failure of ~750% appears at a temperature of ~525°C and an initial strain rate of ~1.4 × 10-4 s-1 with the corresponding strain rate sensitivity coefficient of ~0.46.

Superplastic Behavior of an Al-Cu-Mg-Mn-Ag Alloy

2016 ◽  
Vol 870 ◽  
pp. 185-190
Author(s):  
F.F. Musin ◽  
B.O. Bolshakov ◽  
E. Domracheva
Keyword(s):  
Strain Rate ◽  
Microstructural Evolution ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
Sensitivity Coefficient ◽  
Strain Rates ◽  
Thermomechanical Process ◽  
Average Grain Size ◽  
Elongation To Failure ◽  
Superplastic Properties

The superplastic properties and microstructural evolution of a commercial Al-4.4%Cu-0.5%Mg-0.4%Mn-0.5%Ag-0.1%Ti alloy were examined under tension at temperatures ranging from 450 to 520°C and strain rates ranging from 6.9x10-5 to 6.9x10-2s-1. The refined microstructure with an average grain size of about 11m was produced in thin sheets by a commercially viable thermomechanical process. The highest elongation to failure of 540% was attained at a temperature of 500°C and an initial strain rate of 6.9x10-4 s-1 with the corresponding strain rate sensitivity coefficient of 0.55. The microstructural evolution during superplastic deformation of the aluminum alloy has been studied quantitatively. Processing at temperatures above 475°C and strain rate below 1.4x10-3s-1 resulted in fracturing almost without necking with cavitation playing a major role in the failure. In contrast, at low temperatures and/or high strain rates, fracture occurred in a ductile manner by localized necking. The relationship between superplastic ductility and microstructural evolution is analyzed.

Low-Temperature Superplasticity of the Ni-Based EK61 Superalloy and Application of this Effect to Obtain Sound Solid Phase Joints

2018 ◽  
Vol 385 ◽  
pp. 150-154 ◽  
Author(s):  
Elvina Galieva ◽  
Vener Valitov ◽  
Ramil Lutfullin ◽  
Aerika Bikmukhametova
Keyword(s):  
Low Temperature ◽  
Strain Rate ◽  
Solid Phase ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Sensitivity Factor ◽  
Temperature Range ◽  
Ultrafine Grained ◽  
Nickel Based Alloy ◽  
Superplastic Properties

It is shown that formation of ultrafine-grained structure in EK61 superalloy up to grain sizes less than 1 μm provides to realize superplastic properties. The influence of deformation in the temperature range 600-1100 °C and strain rate range 10-4s-1– 10-3s-1on the microstructure and properties of ultrafine-grained nickel-based alloy EK61 is studied. It is established that in temperature range 750-900 °C the alloy demonstrates superplasticity (SP) characteristics: strain rate sensitivity factor “m” correspond to 0.39-0.59, stable structure and low changes in the form and size of grains. The maximum SP is displayed at temperatures of 800 °C, wherein the elongation is 1431 %. It has been experimentally confirmed that the use of low-temperature superplasticity is a promising for processing sound solid phase joints by pressure welding of similar and dissimilar Ni-based superalloys.

Superplasticity of a Sc and Zr Modified Al-6%Cu Alloy Subjected to ECAE

2010 ◽  
Vol 638-642 ◽  
pp. 291-296
Author(s):  
Ilya Nikulin ◽  
Rustam Kaibyshev ◽  
Sergey Mironov ◽  
Yutaka S. Sato ◽  
Hiroyuki Kokawa ◽  
...  
Keyword(s):  
Strain Rate ◽  
Crystallite Size ◽  
Equal Channel Angular Extrusion ◽  
Volume Fraction ◽  
Rate Sensitivity ◽  
Average Crystallite Size ◽  
Initial Strain Rate ◽  
Sensitivity Coefficient ◽  
Cu Alloy ◽  
Superplastic Properties

Superplasticity in an Al-6%Cu-0.45%Mg-0.4%Mn-0.16%Sc-0.12%Zr alloy subjected to intense plastic straining through equal-channel angular extrusion (ECAE) was studied in tension at strain rates ranging from 5.6×10-4 to 5.6×10-3 s-1 in the temperature interval 350-450°C. The alloy had a non-uniform microstructure with an average crystallite size of 1.2 m. The volume fraction of high-angle grain boundaries was about 57%. In spite of small crystallite size the alloy shows moderate superplastic properties. The highest elongation-to-failures of 320% appeared at a temperature of ~425°C and an initial strain rate of ~1.410-3 s-1, where the strain rate sensitivity coefficient, m, was about 0.33. The relationship between superplastic ductilities and microstructure stability is analyzed.

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