Flow Stress Behavior of Al-3.5Cu-1.0Li-0.4Mg-0.6Zn-0.3Ag Alloy under Hot Tension

2020 ◽  
Vol 1003 ◽  
pp. 20-25
Author(s):  
Dai Hong Xiao ◽  
Ning Liu ◽  
Wen Sheng Liu
Keyword(s):  
Activation Energy ◽  
Dynamic Recovery ◽  
Strain Curve ◽  
Tensile Tests ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Aluminum Lithium Alloy ◽  
Deformation Activation Energy ◽  
Aluminum Lithium ◽  
Heat Activation

The hot deformation behavior and microstructure evolution of Al-3.5Cu-1.0Li-0.4Mg- 0.6Zn-0.3Ag aluminum lithium alloy were investigated by hot tensile tests on Gleeble-1500 thermal simulator at 480-510 °C and strain rates 0.0001-0.1 s-1. The results show that obvious flow steady-state phenomena occur during hot stretching and the main mechanism changes from dynamic recovery to dynamic recrystallization with the increase of temperature and decrease of strain rate. The constitutive equation was calculated using the true stress-strain curve obtained by the hyperbolic sinusoidal pair of deformation activation energy Q and temperature T proposed by Sellars and Tegart. The deformation heat activation energy is 226.783 KJ/mol.

Strain-Rate Effects on Constitutive Behavior of Sn3.8-Ag0.7-Cu Lead-Free Solder

2009 ◽  
Author(s):  
Kok Ee Tan ◽  
John H. L. Pang
Keyword(s):  
Strain Rate ◽  
Yield Stress ◽  
Strain Curve ◽  
Tensile Tests ◽  
Lead Free ◽  
Indentation Hardness ◽  
Strain Rates ◽  
Test Results ◽  
Stress Strain Curve ◽  
Stress Strain

In this paper, the strain-rate dependent mechanical properties and stress-strain curve behavior of Sn3.8Ag0.7Cu (SAC387) solder is presented for a range of strain-rates at room temperature. The apparent elastic modulus, yield stress properties and stress-strain curve equation of the solder material is needed to facilitate finite element modeling work. Tensile tests on dog-bone shaped bulk solder specimens were conducted using a non-contact video extensometer system. Constant strain-rate uni-axial tensile tests were conducted over the strain-rates of 0.001, 0.01, 0.1 and 1 (s−1) at 25°C. The effects of strain-rate on the stress-strain behavior for lead-free Sn3.8Ag0.7Cu solder are presented. The tensile yield stress results were compared to equivalent yield stress values derived from nano-indentation hardness test results. Constitutive models based on the Ramberg-Osgood model and the Cowper-Symond model were fitted for the tensile test results to describe the elastic-plastic behavior of solder deformation behavior.

The Flow Stress and Microstructures of Fe-1.6%Si Silicon Steel

2013 ◽  
Vol 401-403 ◽  
pp. 840-843
Author(s):  
Yong Mei Yu ◽  
De Sheng Du ◽  
Yun Bo Xu
Keyword(s):  
Strain Rate ◽  
Maximum Stress ◽  
Dynamic Recovery ◽  
Strain Curve ◽  
Silicon Steel ◽  
True Stress ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Simulation Experiments ◽  
Average Grain Size

The hot simulation experiments on the Fe-1.6%Si silicon steel were carried out at 900°C and 1200°C, stains of 0.4 and 0.8, and strain rates of 0.5S-1 and 2s-1 respectively. The maximum stress was 90MPa when samples were compressed in the case of 900°C and a strain rate of 2s-1, and which was 30MPa at 900°C and a strain rate of 0.5 s-1. The true stress-strain curve is characterized by dynamic recovery, and a pancaked ferrite microstructure with the average grain size of 378~660μm could be observed at the strain of 0.8 and 0.4 and deformation temperature of 900°C.

scholarly journals Experimental Study on Biaxial Dynamic Compressive Properties of ECC

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1257
Author(s):  
Shuling Gao ◽  
Guanhua Hu
Keyword(s):  
Strain Rate ◽  
Lateral Pressure ◽  
Deformation Modulus ◽  
Strain Curve ◽  
Peak Stress ◽  
Pressure Level ◽  
Strain Rates ◽  
Peak Strain ◽  
Stress Strain Curve ◽  
Toughness Index

An improved hydraulic servo structure testing machine has been used to conduct biaxial dynamic compression tests on eight types of engineered cementitious composites (ECC) with lateral pressure levels of 0, 0.125, 0.25, 0.5, 0.7, 0.8, 0.9, 1.0 (the ratio of the compressive strength applied laterally to the static compressive strength of the specimen), and three strain rates of 10−4, 10−3 and 10−2 s−1. The failure mode, peak stress, peak strain, deformation modulus, stress-strain curve, and compressive toughness index of ECC under biaxial dynamic compressive stress state are obtained. The test results show that the lateral pressure affects the direction of ECC cracking, while the strain rate has little effect on the failure morphology of ECC. The growth of lateral pressure level and strain rate upgrades the limit failure strength and peak strain of ECC, and the small improvement is achieved in elastic modulus. A two-stage ECC biaxial failure strength standard was established, and the influence of the lateral pressure level and peak strain was quantitatively evaluated through the fitting curve of the peak stress, peak strain, and deformation modulus of ECC under various strain rates and lateral pressure levels. ECC’s compressive stress-strain curve can be divided into four stages, and a normalized biaxial dynamic ECC constitutive relationship is established. The toughness index of ECC can be increased with the increase of lateral pressure level, while the increase of strain rate can reduce the toughness index of ECC. Under the effect of biaxial dynamic load, the ultimate strength of ECC is increased higher than that of plain concrete.

Parameters Identification of Johnson-Cook Constitutive Equation for Aluminum Brass

2014 ◽  
Vol 887-888 ◽  
pp. 1032-1035 ◽  
Author(s):  
Chang Chun Di ◽  
Kai Bo Cui ◽  
Jun Qi Qin ◽  
Da Lin Wu
Keyword(s):  
Testing Machine ◽  
Strain Curve ◽  
High Strength ◽  
Dynamic Mechanical Properties ◽  
Model Parameters ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Method Of Least Squares ◽  
Different Temperatures ◽  
Split Hopkinson

Aluminum brass HAL66-6-3-2 is abrasion-resistant alloy with high strength, hardness and wear resistance, corrosion resistance is also well, commonly used in the field of marine and ordnance industry. The quasi static and dynamic mechanical properties were tested through the use of electronic universal testing machine and Split Hopkinson Tension Bar (SHTB). Meanwhile, the material stress-strain curve at different temperatures and different strain rates is also obtained. Based on Johnson-Cook constitutive model, using the method of least squares fitting the experimental data to determine the model parameters, fitting and experimental results agree well.

Understanding Dynamic Recrystallization Behavior through a Delay Differential Equation Approach

2007 ◽  
Vol 558-559 ◽  
pp. 441-448 ◽  
Author(s):  
Jong K. Lee
Keyword(s):  
Differential Equation ◽  
Strain Rate ◽  
Critical Strain ◽  
Strain Curve ◽  
Single Peak ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Strain Behavior ◽  
Delay Differential

During hot working, deformation of metals such as copper or austenitic steels involves features of both diffusional flow and dislocation motion. As such, the true stress-true strain relationship depends on the strain rate. At low strain rates (or high temperatures), the stress-strain curve displays an oscillatory behavior with multiple peaks. As the strain rate increases (or as the temperature is reduced), the number of peaks on the stress-strain curve decreases, and at high strain rates, the stress rises to a single peak before settling at a steady-state value. It is understood that dynamic recovery is responsible for the stress-strain behavior with zero or a single peak, whereas dynamic recrystallization causes the oscillatory nature. In the past, most predictive models are based on either modified Johnson-Mehl-Avrami kinetic equations or probabilistic approaches. In this work, a delay differential equation is utilized for modeling such a stress-strain behavior. The approach takes into account for a delay time due to diffusion, which is expressed as the critical strain for nucleation for recrystallization. The solution shows that the oscillatory nature depends on the ratio of the critical strain for nucleation to the critical strain for completion for recrystallization. As the strain ratio increases, the stress-strain curve changes from a monotonic rise to a single peak, then to a multiple peak behavior. The model also predicts transient flow curves resulting from strain rate changes.

Stress-Strain Curves for Oxygen-Free High Conductivity Copper at Shear Strain Rates of up to 103s-1

1970 ◽  
Vol 185 (1) ◽  
pp. 1149-1158 ◽  
Author(s):  
K. Bitans ◽  
P. W. Whitton
Keyword(s):  
Shear Strain ◽  
Testing Machine ◽  
Shear Bands ◽  
Strain Curve ◽  
Strain Rates ◽  
Adiabatic Shear Bands ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
The Given ◽  
Tubular Specimens

Shear stress-shear strain curves for o.f.h.c. copper at room temperature have been obtained at constant shear strain rates in the range 1 to 103s-1, using thin walled tubular specimens in a flywheel type torsion testing machine. Results show that, for a given value of strain, the stress decreases when the rate of strain is increased. Moreover, the elastic portion of the stress-strain curve tends to disappear as the rate of strain is increased. It is postulated that these effects are due to the formation of adiabatic shear bands in the material when the given rate of strain is impressed rapidly enough. A special feature of the design of the testing machine used is the rapid application of the chosen strain rate.

scholarly journals Hot Compression Deformation and Activation Energy of Nanohybrid-Reinforced AZ80 Magnesium Matrix Composite

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 119 ◽  
Author(s):  
Houyi Li ◽  
Lingling Fan ◽  
Mingyang Zhou ◽  
Youlong Zhou ◽  
Kuan Jiang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Strain Rate ◽  
Matrix Composite ◽  
Hot Deformation ◽  
Strain Rates ◽  
Magnesium Matrix ◽  
Deformation Activation Energy ◽  
Deformation Behaviors ◽  
Carbon Nano Tubes ◽  
Deformation Test

The hot deformation test of the nano silicon carbide (nano-SiC) and carbon nano tubes (CNT) hybrid-reinforced AZ80 matrix composite was performed at compression temperatures of 300–450 °C and strain rates of 0.0001–1 s−1. It could be observed that the flow stress of the nanocomposite rose with the reduction of deformation temperature and the increase of strain rate. The hot deformation behaviors of the composite could be described by the sine-hyperbolic Arrhenius equation, and deformation activation energy (Q) was calculated to be 157.8 kJ/mol. The Q values of the extruded nanohybrid/AZ80 composite in this study and other similar studies on extruded AZ80 alloys were compared in order to analyze the effect of the addition of reinforcement, and the effects of deformation conditions on activation energy were analyzed. Finally, the compression microstructure in an unstable condition was carefully analyzed, and results indicated that the phenomenon of local instability was easy to occur at the compression specimen of the nanohybrid/AZ80 composite under deformation conditions of low temperature with high strain rate (300 °C, 0.1–0.01 s−1), and high temperature with low strain rate (450 °C, 0.0001 s−1).

Stress-Strain Behavior of an Aluminum Alloy Under Transient Strain-Rates

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Y. W. Kwon ◽  
Y. Esmaeili ◽  
C. M. Park
Keyword(s):  
Aluminum Alloy ◽  
Strain Rate ◽  
Fracture Strain ◽  
Strain Curve ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Single Strain ◽  
Transient Strain ◽  
Strain Rate Loading

Because most structures are subjected to transient strain-rate loading, an experimental study was conducted to investigate the stress-strain behaviors of an aluminum alloy undergoing varying strain-rate loading. To this end, uniaxial tensile loading was applied to coupons of dog-bone shape such that each coupon underwent two or three different strain-rates, i.e., one rate after another. As a basis, a series of single-strain-rate tests was also conducted with strain-rates of 0.1–10.0 s−1. When the material experienced multistrain-rate loading, the stress-strain curves were significantly different from any single-strain-rate stress-strain curve. The strain-rate history affected the stress-strain curves under multistrain-rate loading. As a result, some simple averaging of single-strain-rate curves did not predict the actual multistrain-rate stress-strain curve properly. Furthermore, the fracture strain under multistrain-rate loading was significantly different from that under any single-strain-rate case. Depending on the applied strain-rates and their sequences, the former was much greater or less than the latter. A technique was proposed based on the residual plastic strain and plastic energy density in order to predict the fracture strain under multistrain-rate loading. The predicted fracture strains generally agreed well with the experimental data. Another observation that was made was that the unloading stress-strain curve was not affected by the previous strain-rate history.

Hot Deformation Behavior and Microstructure Evolution of Extruded 6069 Al Alloy under Tension

2014 ◽  
Vol 670-671 ◽  
pp. 33-36
Author(s):  
Horng Yu Wu ◽  
Ming Chieh Lin ◽  
Feng Jun Zhu ◽  
Cheng Tao Wu ◽  
Ching Hao Liao ◽  
...  
Keyword(s):  
Dynamic Recovery ◽  
Flow Behavior ◽  
True Strain ◽  
Peak Stress ◽  
Tensile Tests ◽  
Al Alloy ◽  
Strain Rates ◽  
Flow Curves ◽  
Softening Mechanism ◽  
Dynamic Softening

The flow behavior and associated microstructural changes of wrought 6069 Al alloy deformed in tension were analyzed in this work. Tensile tests were conducted on an extruded tube with a thickness of 1.6 mm in the temperature range of 300–500 oC, with initial strain rates from 0.001 to 0.1 s-1. The true stress–true strain curves exhibited a peak stress at a critical strain. The overall level of the flow curve increased when the strain rate was increased and/or the temperature was decreased. The flow curves exhibited a typical flow behavior with dynamic softening and showed that the softening degree after reaching the peak stress was dependent on the deformation conditions. This could be related to the softening mechanism. The main softening mechanism of the alloy was dynamic recovery (DRV) at low temperatures; dynamic recrystallization (DRX) occurred as deformed at high temperatures.

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