Superplastic Deformation of an Al-Li-Cu-Zr Alloy under Uniaxial and Biaxial Tension

1990 ◽  
Vol 196 ◽  
Author(s):  
Ho-Sung Lee ◽  
Amiya K. Mukherjee
Keyword(s):  
Hydrostatic Pressure ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
Biaxial Tension ◽  
Tensile Elongation ◽  
Cavity Growth ◽  
Thickness Strain ◽  
Rate Dependent ◽  
Dependent Flow ◽  
Zr Alloy

ABSTRACTThe superplasticity of an Al-Li-Cu-Zr alloy has been studied under uniaxial tension and biaxial bulging conditions using hydrostatic pressure. An optimum tensile elongation of 850% at a strain rate of 3×10−4 /sec was obtained at 758 K. The maximum true thickness strain was 1.22 for a biaxially deformed specimen under the same conditions. It was shown that strain rate dependent flow hardening was related to necking profile. It was observed that cavity growth during superplastic deformation depended on the type of loading. Under biaxial bulging conditions, the cavities grew by forming cavity fissure networks along the grain boundaries. It was found that, by the superimposition of hydrostatic pressure, cavitation was retarded and the superplastic ductility was increased in both tensile and biaxial deformation.

A Modified Peric Model for Al-Mg Alloy Sheet with Rate-Independent Initial Yield Stress at Warm Temperatures

2019 ◽  
Vol 287 ◽  
pp. 3-7
Author(s):  
Yong Zhang ◽  
Qing Zhang ◽  
Yuan Tao Sun ◽  
Xian Rong Qin
Keyword(s):  
Flow Stress ◽  
Plastic Strain ◽  
Strain Rate ◽  
Yield Stress ◽  
Constitutive Models ◽  
Mg Alloy ◽  
Initial Yield Stress ◽  
Initial Yield ◽  
Rate Dependent ◽  
Dependent Flow

The constitutive modeling of aluminum alloy under warm forming conditions generally considers the influence of temperature and strain rate. It has been shown by published flow stress curves of Al-Mg alloy that there is nearly no effect of strain rate on initial yield stress at various temperatures. However, most constitutive models ignored this phenomenon and may lead to inaccurate description. In order to capture the rate-independent initial yield stress, Peric model is modified via introducing plastic strain to multiply the strain rate, for eliminating the effect of strain rate when the plastic strain is zero. Other constitutive models including the Wagoner, modified Hockett–Sherby and Peric are also considered and compared. The results show that the modified Peric model could not only describe the temperature-and rate-dependent flow stress, but also capture the rate-independent initial yield stress, while the Wagoner, modified Hockett–Sherby and Peric model can only describe the temperature-and rate-dependent flow stress. Moreover, the modified Peric model could obtain proper static yield stress more naturally, and this property may have potential applications in rate-dependent simulations.

Investigation of Superplastic Behavior of NiAI and Ni3Al Duplex Alloy

1996 ◽  
Vol 460 ◽  
Author(s):  
Liu Zhenyun ◽  
Lin Dongliang ◽  
T. L. Lin ◽  
Gu Yuefeng ◽  
Shan Aidang
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Superplastic Deformation ◽  
Empirical Equation ◽  
Tensile Elongation ◽  
Rate Sensitivity ◽  
Superplastic Behavior ◽  
Narrow Temperature Range ◽  
Optical Microstructure ◽  
Duplex Alloy

ABSTRACTThe superplastic behavior of a NiAI and Ni3Al duplex alloy was investigated. It was found that the alloy exhibits superplastic behavior over a narrow temperature range, from 975 °C to 1025°C at the strain rate of 1.52 × 10-4 s-1. A maximum tensile elongation of 149% was obtained at 1000°C with the strain rate sensitivity up to 0.375. The superplastic deformation of the duplex alloy can be approximately described by an empirical equation of the form: ε = Ao2.67 exp(-303,000 / RT). Optical microstructure and TEM observation show that the superplastic behavior mechanism of the investigated alloy is a process of continuous recovery and recrystallization during deformation.

Strain Rate Dependent Flow Stress and Energy Absorption Behaviour of Cast CrMnNi TRIP/TWIP Steels

2011 ◽  
Vol 82 (9) ◽  
pp. 1087-1093 ◽  
Author(s):  
L. Krüger ◽  
S. Wolf ◽  
S. Martin ◽  
U. Martin ◽  
A. Jahn ◽  
...  
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Energy Absorption ◽  
Rate Dependent ◽  
Twip Steels ◽  
Dependent Flow

Strain-Rate-Dependent Flow Stress and Failure of an Mg-PSZ Reinforced TRIP Matrix Composite Produced by Spark Plasma Sintering

2012 ◽  
Vol 83 (6) ◽  
pp. 521-528 ◽  
Author(s):  
Sabine Decker ◽  
Lutz Krüger ◽  
Sarah Richter ◽  
Stefan Martin ◽  
Ulrich Martin
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Spark Plasma Sintering ◽  
Matrix Composite ◽  
Rate Dependent ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Dependent Flow

scholarly journals Strain Rate Dependent Flow Stress Characterization Using Piezo-actuated Micropress

2014 ◽  
Vol 81 ◽  
pp. 1451-1456 ◽  
Author(s):  
Muhammad Taureza ◽  
Sylvie Castagne ◽  
Tegoeh Tjahjowidodo ◽  
Peng Hu
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Rate Dependent ◽  
Dependent Flow

Superplastic Deformation Behavior of Spray Formed High Speed Tool Steel at 820°C

2007 ◽  
Vol 561-565 ◽  
pp. 91-94
Author(s):  
Can Dong Zhou ◽  
Jun Fei Fan ◽  
Hai Rong Le ◽  
Jing Guo Zhang
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
High Speed ◽  
Tensile Axis ◽  
Tensile Elongation ◽  
High Speed Steel ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Dislocation Creep

Being examined by tensile tests at 820°C with initial strain rates of 2.5×10-4 s-1, 5.0×10-3 s-1and 1.0×10-1 s-1, the hot-rolled spay formed high speed steel (SF-HSS) had superplastic properties. With έ=2.5×10-4 s-1and 5.0×10-3 s-1, the σ-ε curves indicate that there has occurred dynamic recrystallization at the later stage of deformation.The tensile elongation decreases monotonously with strain rate increasing. The strain rate sensitivity m =dlogσ/dlog έ is about 0.23. In the sub-surface of fractured SF-HSS samples with έ=2.5×10-4 s-1,, most of holes on the subsurface are observed to distribute near the carbides and arranged along the tensile axis direction. The interface between coarse carbides and matrix is very weak sites where the holes are easy to nucleate and connect to cracks during deformation. In the necked region, fine carbide particles on the grain boundary have pinned the slip of dislocations and formed dislocation wall inside the grain. Dynamic recrystallization and some climb of dislocations has occurred. The superplastic deformation mechanism with έ=2.5×10-4 s-1 was dislocation creep mechanism controlled by dynamic recrystallization. During deformation, the role of some carbide in the materials was to retard the grain growth and keep SF-HSS having fine equiaxed grain size and remain stable.

Key Microstructural Changes during High Strain Rate Superplastic Deformaion of an Al-Zn-Mg-Cu-Zr Alloy Containing Sc

2011 ◽  
Vol 702-703 ◽  
pp. 366-369
Author(s):  
A.K. Mukhopadhyay ◽  
A. Kumar ◽  
K.S. Prasad ◽  
S. Raveendra ◽  
Indradev Samajdar
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
Considerable Increase ◽  
High Strain ◽  
Al Alloy ◽  
Number Density ◽  
Microstructural Changes ◽  
Early Stages ◽  
Zr Alloy

The changes in texture and microstructure that occur during superplastic deformation (SPD) of a suitably thermo-mechanically processed (TMP) Al alloy AA7010 containing Sc at a temperature and strain rate combination of 475°C, 1.9x10-2s-1 have been examined. It is observed that during the early stages of SPD, there is a significant increase in the Brass {110}<112> component as well as a considerable increase in the S {123}<634> component. Whilst, these components gradually decrease leading to the randomization of texture as the SPD process progresses to larger strains. These results are discussed in terms of the nature of the TMP together with significant variations in the number density of Al3ScxZr1-x dispersoids and percentage recrystallization with strain.

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