scholarly journals Low-Temperature Superplasticity and Deformation Mechanism of Ti-6Al-4V Alloy

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1212 ◽  
Author(s):  
Ge Zhou ◽  
Lijia Chen ◽  
Lirong Liu ◽  
Haijian Liu ◽  
Heli Peng ◽  
...  
Keyword(s):  
Low Temperature ◽  
Deformation Mechanism ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Deformation Mechanisms ◽  
Temperature Deformation ◽  
Deformation Activation Energy ◽  
Before And After ◽  
Different Temperatures ◽  
Elongation To Failure

The low-temperature superplastic tensile behavior and the deformation mechanisms of Ti-6Al-4V alloy are investigated in this paper. Through the experiments carried out, elongation to failure (δ) is calculated and a set of values are derived that subsequently includes the strain rate sensitivity exponent (m), deformation activation energy (Q) at low-temperature superplastic deformation, and the variation of δ, m and Q at different strain rates and temperatures. Microstructures are observed before and after superplastic deformation. The deformation mechanism maps incorporating the density of dislocations inside grains at temperatures of 973 and 1123 K are drawn respectively. By applying the elevated temperature deformation mechanism maps based on Burgers vector compensated grain size and modulus compensated stress, the dislocation quantities and low-temperature superplastic deformation mechanisms of Ti-6Al-4V alloy at different temperatures within appropriate processing regime are elucidated.

scholarly journals Rheological Law and Mechanism for Superplastic Deformation of Ti–6Al–4V

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3520
Author(s):  
Chao Liu ◽  
Ge Zhou ◽  
Xin Wang ◽  
Jiajing Liu ◽  
Jianlin Li ◽  
...  
Keyword(s):  
Low Temperature ◽  
Deformation Mechanism ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Material Model ◽  
Sensitivity Index ◽  
Compression Tests ◽  
Dynamic Material Model ◽  
Strain Rate Sensitivity Index ◽  
Evolution Laws

The behaviors of and mechanisms acting in Ti–6Al–4V alloy during low-temperature superplastic deformation were systematically studied by using a Gleeble-3800 thermocompression simulation machine. Focusing on the mechanical behaviors and microstructure evolution laws during low-temperature superplastic compression tests, we clarified the changing laws of the strain rate sensitivity index, activation energy of deformation, and grain index at varying strain rates and temperatures. Hot working images based on the dynamic material model and the deformation mechanism maps involving dislocation quantity were plotted on the basis of PRASAD instability criteria. The low-temperature superplastic compression-forming technique zone and the rheological instability zone of Ti–6Al–4V were analyzed by using hot processing theories. The dislocation evolution laws and deformation mechanisms of the grain size with Burgers vector compensation and the rheological stress with modulus compensation during the low-temperature superplastic compression of Ti–6Al–4V were predicted by using deformation mechanism maps.

scholarly journals Dislocation-Controlled Low-Temperature Superplastic Deformation of Ti-6Al-4V Alloy

2021 ◽  
Vol 7 ◽  
Author(s):  
Chao Liu ◽  
Xin Wang ◽  
Ge Zhou ◽  
Feng Li ◽  
Siqian Zhang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Strain Rate ◽  
Deformation Mechanism ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Stress Index ◽  
Sensitivity Index ◽  
Dislocation Glide ◽  
Superplastic Properties ◽  
Superplastic Tension

The superplastic tension and deformation mechanism of Ti-6Al-4V alloy at 923 K and a tensile speed of 10−3, 5 × 10−3, or 5 × 10−2 s−1 was studied on an AG 250KNE electronic tension tester. Through theoretical modeling, the unit dislocation count of this alloy during superplastic deformation was introduced into the Ruano–Wadsworth–Sherby (R-W-S) deformation mechanism map, and a new deformation mechanism map involving dislocation count was plotted. Thereby, the mechanism underling the low-temperature superplastic deformation of this alloy was predicted. It was found the superplastic tension of Ti-6Al-4V at the tested temperature was controlled by dislocation movement, and with an increase in strain rate, the deformation transited from the dislocation-controlled mechanism with a stress index of 4 to the dislocation glide mechanism with a stress index of 5 or 7. At the strain rate of 10−3 s−1, this alloy reached the largest tension rate of 790% and strain rate sensitivity index of 0.52 and had excellent low-temperature superplastic properties.

A Comparative Study on Superplasticity of Mg-Zn-Y-Zr Processed by ECAE and Hot Rolling

2007 ◽  
Vol 551-552 ◽  
pp. 203-208 ◽  
Author(s):  
Wei Neng Tang ◽  
Hong Yan ◽  
Rong Shi Chen ◽  
En Hou Han
Keyword(s):  
Hot Rolling ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Sensitivity Coefficient ◽  
Grain Boundary Sliding ◽  
Diffusional Creep ◽  
Dislocation Creep ◽  
Fine Grained ◽  
Microstructure Observation ◽  
Elongation To Failure

Superplastic deformation (SPD) behaviors of two fine-grained materials produced by ECAE and hot rolling methods have been contrastively studied in this paper. It is found that the optimum superplastic condition in as-ECAEed material was at 350°C and 1.7×10-3s-1 with elongation to failure about 800%; while in as-rolled material, the largest elongation to failure about 1000% was obtained at 480°C and 5.02×10-4s-1. Microstructure observation showed that grain evolution and cavitation behavior were different in these two materials during superplastic deformation. The controlled mechanisms for superplasticity, i.e. grain boundary sliding (GBS), dislocation creep and diffusional creep, at different deformation conditions were discussed in terms of strain rate sensitivity coefficient, stress exponent and activity energy.

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.

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.

The Influence of Microstructure on Superplastic Behaviours of γ-TiAl Alloys

1998 ◽  
Vol 552 ◽  
Author(s):  
J. Sun ◽  
J. S. Wu ◽  
G. X. Hu ◽  
Y. H. He ◽  
B. Y. Huang
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Maximum Elongation ◽  
Tial Alloys ◽  
Different Temperatures ◽  
Incremental Strain

ABSTRACTIn this work, superplastic behaviours in Ti-33A1–3Cr-0.5Mo (wt%) γ-TiAl alloys with two different initial microstructures of near gamma (NG) and duplex (DM) structure were investigated with respect to the effect of testing temperatures and strain rates. At 1050°C and a strain rate of 8×10–5 S–1, a maximum elongation of 570% was observed for NG-TiAl and a maximum elongation of 467% for DM-TiAl. The relations of flow stress and strain rate sensitivity vs. strain rates at different temperatures were also determined by incremental strain rate tests. The results showed that the value of strain rate sensitivity is higher and the flow stress is lower for NG than those for DM at the same condition. The microstructural evolution during superplastic deformation was examined and correlated to the mechanical properties for these two alloys. The influence of microstructure on the superplastic behaviours of γ-TiAl alloys, and possible superplastic deformation mechanisms were finally discussed.

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