Abnormal Effects of Temperature and Strain Rate on the Ductility of a Carbon Nanotubes Reinforced Al Alloy Composite

2016 ◽  
Vol 877 ◽  
pp. 251-257
Author(s):  
Wei Jun He ◽  
Chun Hong Li ◽  
Zhi Qiang Li ◽  
Bai Feng Luan ◽  
Qing Liu
Keyword(s):  
Carbon Nanotubes ◽  
Strain Rate ◽  
Effect Of Temperature ◽  
Al Alloy ◽  
Alloy Composite ◽  
Compression Tests ◽  
Before And After ◽  
Flake Powder Metallurgy ◽  
Effects Of Temperature ◽  
Gleeble 3500 System

Carbon nanotubes reinforced aluminum alloy (CNTs/Al alloy) composite was fabricated by the method of flake powder metallurgy. With Gleeble-3500 system, hot compression tests at different temperatures and strain rates were conducted to investigate the effect of temperature and strain rate on the deformation behaviors of the CNTs/Al alloy composite. Experimental results show that the composite’s ductility is worse at higher deformation temperature within range of 300 oC-450 oC. Additionally, the composite’s ductility is better at higher strain rate, which is against general knowledge. The microstructure before and after deformation were characterized by SEM and TEM. It demonstrates that the grain size of the composite is always in the nanoscale. The abnormal effects of temperature and strain rate on the ductility may be explained by the evolution of work hardening capability at different deformation conditions.

scholarly journals Experimental Measurements of Mechanical Properties of PUR Foam Used for Testing Medical Devices and Instruments Depending on Temperature, Density and Strain Rate

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4560 ◽  
Author(s):  
Zdenek Horak ◽  
Karel Dvorak ◽  
Lucie Zarybnicka ◽  
Hana Vojackova ◽  
Jana Dvorakova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Mechanical Testing ◽  
Medical Devices ◽  
Optical Microscope ◽  
Surgical Instruments ◽  
Effect Of Temperature ◽  
Experimental Measurements ◽  
Compression Tests ◽  
Biomedical Material

Rigid polyurethane (PUR) foam is products used as a biomedical material for medical device testing. Thermal stability is a very important parameter for evaluating the feasibility of use for testing surgical instrument load during drilling. This work aimed to perform experimental measurements to determine the dependence of the mechanical properties of a certified PUR on temperature, strain rate and density. Experimental measurements were realised for three types of the PUR samples with different density 10, 25 and 40 pounds per cubic foot. The samples were characterised in terms of their mechanical properties evaluated from tensile and compression tests at temperatures of 25 °C, 90 °C and 155 °C. Furthermore, the structures of the samples were characterised using optical microscope, their thermal properties were characterised by thermogravimetric analysis, and their density and stiffness with the effect of temperature was monitored. The results show that it is optimal not only for mechanical testing but also for testing surgical instruments that generate heat during machining. On the basis of experimental measurements and evaluations of the obtained values, the tested materials are suitable for mechanical testing of medical devices. At the same time, this material is also suitable for testing surgical instruments that generate heat during machining.

Effect of Temperature and Strain Rate on Low-Cycle Fatigue Life of Bi-Sn Eutectic Alloy

2013 ◽  
Author(s):  
Takuma Sato ◽  
Yoshiharu Kariya ◽  
Kazuma Fukui
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Eutectic Alloy ◽  
Low Cycle Fatigue ◽  
Effect Of Temperature ◽  
Eutectic Alloys ◽  
Cycle Fatigue ◽  
Dominant Deformation Mechanism ◽  
Boundary Sliding ◽  
Effects Of Temperature

In this study, the effects of temperature and strain rate on low cycle fatigue life of Bi-Sn eutectic alloys have been studied. The fatigue life improves with the increasing of temperature and the decreasing of strain rate. This is a reverse phenomenon from characteristics found in general metals. As temperature increases and strain rate decreases, grin boundary sliding becomes the dominant deformation mechanism and the fatigue ductility coefficient increases, resulting in an improvement of fatigue life. To the extent of this study, dependence on temperature and strain rate can be expressed by Manson-Coffin’s law modified using Z-parameters.

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.

scholarly journals Dynamic Precipitation in Mg–8.08Gd–2.41Sm–0.30Zr Alloy during Hot Compression

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2147
Author(s):  
Limin Zhu ◽  
Quanan Li ◽  
Qing Zhang ◽  
Xiaoya Chen
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Compression ◽  
Strain Rates ◽  
Dynamic Precipitation ◽  
Compression Tests ◽  
Effects Of Temperature ◽  
Compression Temperature

Dynamic precipitation of Mg–8.08Gd–2.41Sm–0.30Zr (wt %) alloy during hot compression was studied in the present work. The effects of temperature and strain rate on dynamic precipitation, and the effects of dynamic precipitation on dynamic recrystallization (DRX) and microhardness, were systematically analyzed. For this purpose, hot compression tests were conducted at the strain rates of 0.002~1 s−1 and temperatures of 350~500 °C, with the compaction strain of 70% (εmax = 0.7). The obtained results revealed that dynamic precipitation occurred during hot compression at 350~400 °C, but did not occur for T ≥ 450 °C. The precipitates were demonstrated to be β-Mg5Gd with a size of 200~400 nm, and they were distributed in the DRXed region. Dynamic precipitation occurred at strain rates in the 0.002~0.01 s−1 range, but did not occur when the strain rates were in the 0.1~1 s−1 range for the hot compression temperature of 350 °C. The relationships between the hot compression temperature (T) and DRXed grain size (lnd), microhardness (Hv), and DRXed grain size (d−1/2) of Mg–8.08Gd–2.41Sm–0.30Zr alloy were obtained.

scholarly journals Experimental Investigation of the Effect of Temperature and Strain Rate on the Superplastic Deformation Behavior of Ti-Based Alloys in the (α+β) Temperature Field

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 819 ◽  
Author(s):  
Ahmed Mosleh ◽  
Anastasia Mikhaylovskaya ◽  
Anton Kotov ◽  
Waheed AbuShanab ◽  
Essam Moustafa ◽  
...  
Keyword(s):  
Strain Rate ◽  
Strain Hardening ◽  
Deformation Behavior ◽  
Superplastic Deformation ◽  
Al Alloys ◽  
Effect Of Temperature ◽  
Al Alloy ◽  
Softening Effect ◽  
Elongation To Failure ◽  
Hardening Coefficient

This paper presents the effect of temperature and strain rate on the superplastic deformation behavior of Ti-3%Mo-1%V-4%Al, Ti-4%V-6%Al, and Ti-1.8%Mn-2.5%Al alloys, which have different initial microstructures. The microstructure, before and after superplastic deformation in the deformation regimes that provided the maximum elongation, was analyzed. The deformation regimes, corresponding to the minimum strain hardening/softening effect, provided a higher elongation to failure due to their low tendency toward dynamic grain growth. As the values of stress became steady (σs), the elongation to failure and strain-hardening coefficient were analyzed under various temperature–strain rate deformation regimes. The analysis of variance of these values was performed to determine the most influential control parameter. The results showed that the strain rate was a more significant parameter than the temperature, with respect to the σs, for the investigated alloys. The most influential parameter, with both the elongation to failure and strain-hardening coefficient, was the temperature of the Ti-3%Mo-1%V-4%Al and Ti-1.8%Mn-2.5%Al alloys and the strain rate of the Ti-4%V-6%Al alloy.

Determination of the Onset of the Dynamic Recystallization of a 7075 Al Alloy

2013 ◽  
Vol 752 ◽  
pp. 105-114 ◽  
Author(s):  
Tamás Mikó ◽  
Peter Barkoczy
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Critical Stress ◽  
Al Alloy ◽  
Strain Rates ◽  
Compression Tests ◽  
Critical Stresses ◽  
Work Hardening Rate ◽  
Initial States

This paper presents an investigation about the occurrence of the dynamic recrystallization (DRX) during hot forming. Two 7075 aluminum alloy samples in different initial states were examined by compression tests at temperatures between 573 K and 723 K and constant strain rates ranging from 0.002 to 2 (s-1) with the maximum strain of 0.5 mm/mm. The activation energies of the examined aluminium were calculated, being 137.7 kJ/mol and 142.4 kJ/mol. The critical stresses and strains for the initiation of the dynamic recrystallization were determined using a numerical method based on the changes of the work hardening rate (θ) as a function of the flow stress (σ) or a strain (ε), respectively. Based on the micrographs taken after the deformations it was revealed that in some cases only dinamyc recovery (DRV) whereas in others DRX occurred under the applied examination conditions. The critical stress which belongs to the onset of the DRX or the DRV depend on the temperature, the strain rate, and the initial grain size. The critical and maximal stresses and the corresponding strain values at different conditions were determined. In the examined range of deformation, temperature and strain rate, the critical rations are σ_c/σ_p= (0.93-0.99) and εc/ εp = (0.3-0.74), respectively.

Effect of Strain Rate on Dynamic Recrystallization Behavior for V Micro-Alloy High-Carbon Steel

2012 ◽  
Vol 602-604 ◽  
pp. 401-404
Author(s):  
An Chao Ren ◽  
Yu Ji ◽  
Gui Feng Zhou ◽  
Ze Xi Yuan
Keyword(s):  
Carbon Steel ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
High Carbon Steel ◽  
Constant Strain Rate ◽  
Grain Morphology ◽  
Peak Stress ◽  
Compression Tests ◽  
High Carbon ◽  
Before And After

Isothermal constant strain rate compression tests on high-carbon steel are carried out under strain rate of 1s-1, 10s-1 and 50s-1 respectively and deformation of 0.7 using the THERMECMASTOR-Z thermal simulator at a temperature of 1000°C. The austenite grain morphology before and after deformation and the true stress-strain curves during the deformation process are analyzed. The experimental results show that increased strain rate can obviously contribute to the grain refinement, and when the strain rate is at low level (e.g. 1s-1)，increased strain rate can further help refine the grains. And under the same temperature conditions, as the deformation rate rises, peak stress will move toward the direction of strain increment，thus the dynamic recrystallization is not apt to occur.

Effect of Small Addition of Si on Superplastic Elongation at Room Temperature in Zn-Al Eutectoid Superplastic Alloy

2014 ◽  
Vol 922 ◽  
pp. 328-331 ◽  
Author(s):  
Yuhei Kamiya ◽  
Masaki Ninomiya ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Room Temperature ◽  
Tensile Tests ◽  
Al Alloy ◽  
Superplastic Behavior ◽  
Superplastic Alloy ◽  
Average Grain Size ◽  
Before And After ◽  
Si Content

Recent experimental data have revealed that a small amount of impurity can significantly influence the superplastic behavior in Zn-Al eutectoid superplastic alloy. However, the effect of Si content on the superplastic behavior in Zn-Al alloy has not been reported. In this study, the superplastic behavior at a room temperature of two grades of the Zn-Al eutectoid superplastic alloy was studied under identical conditions of grain size, temperature, and strain rate. These two grades were prepared from high-purity Zn, Al and Al-Si alloy using the same procedure but different Si impurity levels; Zn-Al-10Si and Zn-Al-1000Si contain 10 and 900 wt. ppm of Si, respectively. As a result of annealing treatments, an average grain size of 0.6 μm in both grades. To investigate the effects of Si content on superplastic properties, the tensile tests were performed at a room temperature of 298 K and a constant strain rate of 1×10-3 s-1. Microstructures before and after the tensile tests was observed using a scanning electron microscope. The experimental results show that the elongations decreased with increasing the Si content. In contrast, the flow stress of Zn-Al alloys was not affected by the Si content. On the microstructure observation of the two grades of the Zn-Al alloy before and after the tensile tests, cavities existed at grain boundaries and strain enhanced grain growth was observed.

The Effect of Temperature and Strain-Rate Sensitivity on Formability of AA 5754

2012 ◽  
Vol 217-219 ◽  
pp. 1596-1601 ◽  
Author(s):  
Mevlut Turkoz ◽  
Selcuk Halkacı ◽  
Muammer Koç
Keyword(s):  
Aluminum Alloys ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Effect Of Temperature ◽  
Different Temperatures ◽  
Warm Hydroforming ◽  
Effects Of Temperature ◽  
Different Strains

Aluminum alloys have limited usage because of their limited formability at room temperatures. In order to design and develop more parts made of aluminum, new forming techniques such as hydroforming, warm forming and warm hydroforming have been researched to overcome the low formability issues. This, in turn, necessitates understanding and modeling the behavior of aluminum alloys at different temperatures and strain rates. This paper deals with the investigation of the effect of temperature and strain rate sensitivity on the formability of AA 5754 aluminum alloy. Tensile tests were carried out at temperatures of 20,100,180 and 260°C and forming rates of 25, 100 and 250 mm/min. The mechanical properties and flow curves were obtained and the strain rate sensitivities were calculated at different strains and temperatures. The effects of temperature and strain rate sensitivity on the formability were introduced.

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