Strain Rate Sensitivity and Adiabatic Shear Deformation of an Advanced Al-Mg Alloy

2014 ◽  
Vol 941-944 ◽  
pp. 72-76
Author(s):  
Yu Jing Lang ◽  
Gu Xin Zhou ◽  
Wen Liu ◽  
Jie Hao ◽  
Li Qiao ◽  
...  
Keyword(s):  
Strain Rate ◽  
Fracture Strain ◽  
Dynamic Deformation ◽  
Dynamic Compression ◽  
Shear Bands ◽  
Rate Sensitivity ◽  
Optical Microscope ◽  
Mg Alloy ◽  
Al Alloy ◽  
Strain Rates

In order to develop new Al alloy, the quasi-static and dynamic compression deformation behavior of an advanced Al-Mg alloy, which contained Zn and rare earth, were investigated. Deformed microstructures in the shear bands of this alloy were characterized by optical microscope. Results show that the compressive strengths increase with strain and strain rates being increased, and microstructures of deformed Al-Mg alloy along compression directions are sensitive to strain rates. The distorted deformation twins near the deformed band can be formed under low strain rate of 5.6×10-3 s-1, while multiple shear bands slipping can be induced by dynamic deformation under high strain rates from 1.9×103 s-1 to 5×103 s-1. Therefore, compressive strength and fracture strain of dynamic deformation are higher than that of the quasi-static deformation, which is attributed to the strain hardening and grain refining in the multiple shear bands.

Deformation Behavior and Microstructure Evolution of 6063 Alloy during Hot Compression

2018 ◽  
Vol 913 ◽  
pp. 63-68 ◽  
Author(s):  
Zhu Hua Yu ◽  
Da Tong Zhang ◽  
Wen Zhang ◽  
Cheng Qiu
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Shear Bands ◽  
Hot Compression ◽  
Al Alloy ◽  
Strain Rates ◽  
Compression Tests ◽  
Softening Effect ◽  
6063 Al Alloy ◽  
Gleeble 3500

Hot compression tests of homogenized 6063 Al alloy were carried out in the temperatures range from 390°C to 510°C and strain rates from 1s-1 to 20s-1 on a Gleeble-3500 thermal simulation machine. The results showed that the flow stress decreased with increasing deformation temperature or decreasing strain rate. The dynamic softening effect was more obvious when the alloy was deformed at strain rate of 20 s-1. The Arrhenius-type constitutive equation with strain compensation can accurately describe the flow stress of 6063 aluminum alloy during hot compression. Shear bands appeared in grains interior when the alloy deformed at high strain rates, corresponding to high Zenner-Hollomon (Z) parameters. When deformed under the conditions with low Z parameters, the dynamic recrystallization started occurred.

Grain Refinement during Superplastic Deformation of Coarse-Grained Al-Mg-Cu Alloys

2006 ◽  
Vol 509 ◽  
pp. 75-80 ◽  
Author(s):  
M.I. Cruz-Palacios ◽  
D. Hernández-Silva ◽  
L.A. Barrales-Mora ◽  
M.A. García-Bernal
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Grain Refinement ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Mg Alloy ◽  
Coarse Grained ◽  
Dislocation Creep ◽  
Rolled Plate ◽  
Strain Rates

In the present study the superplastic behavior of Al-6%Mg–0.5%Cu and Al–8%Mg– 0.5%Cu in a coarse grain size condition has been studied. The alloys are melted in an electrical furnace under argon atmosphere. The ingots (25 mm thick) are homogenized at 400 °C during 72 h and then rolled at 430 °C to a thickness of 5 mm. The mean grain size after rolling is 55 µm for the 6%Mg alloy and 61 µm for the 8%Mg alloy. Tensile test specimens are machined from the rolled plate in the rolling direction. Strain-rate-change tests at temperatures between 300 and 450 °C and strain rates between 1x10-4 and 1x10-1 s-1 are carried out to determine the strain rate sensitivity of the flow stress. Finally, elongation to failure tests are conducted at temperatures and strain rates where the alloys show a high strain rate sensitivity. Elongations higher than 390 % are obtained for the 8%Mg alloy. It is observed that the grip regions of the deformed samples show coarser grains than the regions near to the fracture surface. This means that grain refinement takes place during deformation, suggesting that the principal deformation mechanism is dislocation creep.

scholarly journals Effects of Cu Addition on Mechanical Behaviour, Microstructural Evolution and Anti-Corrosion Performance of TiAl-Based Intermetallic Alloy under Different Strain Rates

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5056
Author(s):  
Cheng-Hsien Kuo ◽  
Tao-Hsing Chen ◽  
Ting-Yang Zeng
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Fracture Strain ◽  
Split Hopkinson Pressure Bar ◽  
Constant Strain Rate ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Phase Content ◽  
Corrosion Performance ◽  
Hopkinson Pressure Bar

TiAl-based intermetallic alloys are prepared with Cu concentrations of 3–5 at.% (atomic ratio). The mechanical properties and microstructural characteristics of the alloys are investigated under static and dynamic loading conditions using a material testing system (MTS) and split-Hopkinson Pressure Bar (SHPB), respectively. The electrochemical properties of the various alloys are then tested in Ringer’s solution. It is shown that the level of Cu addition significantly affects both the flow stress and the ductility of the samples. For Cu contents of 3 and 4 at.%, respectively, the flow stress and strain rate sensitivity increase at higher strain rates. Furthermore, for a constant strain rate, a Cu content of 4 at.% leads to an increased fracture strain. However, for the sample with the highest Cu addition of 5 at.%, the flow stress and fracture strain both decrease. The X-ray diffraction (XRD) patterns and optical microscopy (OM) images reveal that the lower ductility is due to the formation of a greater quantity of γ phase in the binary TiAl alloy system. Among all the specimens, that with a Cu addition of 4 at.% has the best anti-corrosion performance. Overall, the results indicate that the favourable properties of the TiAlCu4 sample stem mainly from the low γ phase content of the microstructure and the high α2 phase content.

Effect of Strain-Rate on the Fracture Morphology of LY2 Aluminum Alloy by Laser Shock Processing

2011 ◽  
Vol 464 ◽  
pp. 677-680 ◽  
Author(s):  
Jin Zhon Lu ◽  
Kai Yu Luo ◽  
L. Zhang ◽  
J.W. Zhong ◽  
X.G. Cui ◽  
...  
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Fracture Morphology ◽  
Al Alloy ◽  
Strain Rates ◽  
Laser Shock ◽  
Laser Shock Processing ◽  
Dimple Fracture ◽  
Shock Processing

The strain-rate sensitivity of LY2 aluminum (Al) alloy subjected to laser shock processing (LSP) was investigated according to the fracture morphology at strain-rates ranging from 0.00001 s-1 to 0.1 s-1. The fracture morphology was observed by the scanning electron microscopy (SEM). Fracture morphology at different strain-rates suggested that LY2 Al alloy after LSP seemed to evolve towards a more ductile dimple fracture mode with increasing the strain-rates. The relations underlying the fracture morphology and strain-rate sensitivity were also addressed.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

Dynamic Deformation Behavior of As-Extruded Mg-Gd-Y Magnesium Alloy and the Microstructural Evolution

2011 ◽  
Vol 284-286 ◽  
pp. 1579-1583
Author(s):  
Ping Li Mao ◽  
Zheng Liu ◽  
Chang Yi Wang ◽  
Feng Wang
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Deformation Behavior ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Deformation ◽  
Strain Rates ◽  
Compression Axis ◽  
Deformation Localization ◽  
Dynamic Deformation Behavior

The dynamic deformation behavior of an as-extruded Mg-Gd-Y magnesium alloy was studied by using Split Hopkinson Pressure Bar (SHPB) apparatus under high strain rates of 102 s-1 to 103s-1 in the present work, in the mean while the microstructure evolution after deformation were inspected by OM and SEM. The results demonstrated that the material is not sensitive to the strain rate and with increasing the strain rate the yield stress of as-extruded Mg-Gd-Y magnesium alloy has a tendency of increasing. The microstructure observation results shown that several deformation localization areas with the width of 10mm formed in the strain rates of 465s-1 and 2140s-1 along the compression axis respectively, and the grain boundaries within the deformation localization area are parallel with each other and are perpendicular to the compression axis. While increasing the strain rate to 3767s-1 the deformation seems become uniform and all the grains are compressed flat in somewhat. The deformation mechanism of as-extruded Mg-Gd-Y magnesium alloy under high strain rate at room temperature was also 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.

Strain-Rate Effect on the Tensile Behaviour of High Strength Alloys

2011 ◽  
Vol 82 ◽  
pp. 124-129 ◽  
Author(s):  
Ezio Cadoni ◽  
Matteo Dotta ◽  
Daniele Forni ◽  
Stefano Bianchi
Keyword(s):  
Strain Rate ◽  
Rate Sensitivity ◽  
High Strength ◽  
Constitutive Law ◽  
Tensile Behaviour ◽  
Strain Rates ◽  
Cross Sectional ◽  
Split Hopkinson Tensile Bar ◽  
Wide Range ◽  
First Results

In this paper the first results of the mechanical characterization in tension of two high strength alloys in a wide range of strain rates are presented. Different experimental techniques were used for different strain rates: a universal machine, a Hydro-Pneumatic Machine and a JRC-Split Hopkinson Tensile Bar. The experimental research was developed in the DynaMat laboratory of the University of Applied Sciences of Southern Switzerland. An increase of the stress at a given strain increasing the strain-rate from 10-3 to 103 s-1, a moderate strain-rate sensitivity of the uniform and fracture strain, a poor reduction of the cross-sectional area at fracture with increasing the strain-rate were shown. Based on these experimental results the parameters required by the Johnson-Cook constitutive law were determined.

scholarly journals Study on the dynamic properties of AM-SLM AlSi10Mg alloy using the Split Hopkinson Pressure Bar (SHPB) technique

2018 ◽  
Vol 183 ◽  
pp. 04005 ◽  
Author(s):  
Bar Nurel ◽  
Moshe Nahmany ◽  
Adin Stern ◽  
Nahum Frage ◽  
Oren Sadot
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Properties ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Static Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Additive manufacturing by Selective Laser Melting of metals is attracting substantial attention, due to its advantages, such as short-time production of customized structures. This technique is useful for building complex components using a metallic pre-alloyed powder. One of the most used materials in AMSLM is AlSi10Mg powder. Additively manufactured AlSi10Mg may be used as a structural material and it static mechanical properties were widely investigated. Properties in the strain rates of 5×102–1.6×103 s-1 and at higher strain rates of 5×103 –105 s-1 have been also reported. The aim of this study is investigation of dynamic properties in the 7×102–8×103 s-1 strain rate range, using the split Hopkinson pressure bar technique. It was found that the dynamic properties at strain-rates of 1×103–3×103 s-1 depend on a build direction and affected by heat treatment. At higher and lower strain-rates the effect of build direction is limited. The anisotropic nature of the material was determined by the ellipticity of samples after the SHPB test. No strain rate sensitivity was observed.

Analysis of Twinning Behavior of Ti-2V Alloy Compressed at High Strain Rate

2017 ◽  
Vol 898 ◽  
pp. 231-235
Author(s):  
Qiao Chu Wang ◽  
Rui Liu ◽  
Wen Jun Ye ◽  
Yang Yu ◽  
Xiao Yun Song ◽  
...  
Keyword(s):  
Strain Rate ◽  
Mechanical Response ◽  
Dynamic Compression ◽  
Orientation Imaging Microscopy ◽  
Optical Microscope ◽  
Dynamic Mechanical Properties ◽  
Hopkinson Pressure Bar ◽  
Deformation Degree ◽  
Ebsd Technique ◽  
Pressure Bar

The spilt Hopkinson pressure bar was employed to study dynamic compression mechanical response of Ti-2V alloy. The dynamic compression experiment was carried at a strain rate of 3000s-1. The microstructure of deformed specimen with ε=0.05, 0.18, 0.26 was observed by optical microscope. Electron Back-Scattered Diffraction (EBSD) technique was applied to confirm the types of twinning. Through analyzing mechanical response and microstructure evolution rule, the effect of element vanadium and deformation degree on dynamic mechanical properties and twinning deformation behavior was revealed. The results indicate that twinning is the prime dynamic deformation mechanism in Ti-2V alloy and the twinning fraction is increasingly raised during the deformation process. The twinning types, confirmed by Orientation Imaging Microscopy software, are namely {102}, {112} and {111} twinning. And the number of {111} twinning is far less than the other two types of twinning.

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