Pressing Process of Al-W Alloy Powder and Constitutive Model the Pressed Billet at Elevated Temperatures

2014 ◽  
Vol 685 ◽  
pp. 11-17
Author(s):  
Yao Jin Wu ◽  
Yong Xue ◽  
Zhi Ming Zhang ◽  
Ya Wei Huang ◽  
Qian Qian Wang ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Alloy Powder ◽  
Elevated Temperatures ◽  
Testing Machine ◽  
Constant Strain Rate ◽  
Thermal Simulation ◽  
Powder Pressing ◽  
Simulation Testing ◽  
Relation Model

Al-W alloy billets were produced by powder pressing at room temperature and subsequent hot pressing. Quantities of billets were compressed at constant strain rate and temperature with 60% height reduction on Gleeble-3800 thermal simulation testing machine to study the plastic flow behaviors of the test alloy. The temperature of the compression processes ranged from 450 to 570oC. The strain rate was varied between 0.001 and 1s−1. The regularity of flow stress for the test alloy varied at elevated temperatures was studied. The activation energy during hot deformation is 757.943 kJ/mol by calculated, and the Arrhenius constitutive relation model was established. Keywords: Al-W alloy, powder metallurgy, thermal simulation, constitutive model

scholarly journals Influence of Deformation Controlled Strain Rate on Tensile and Compression Behaviour of Magnesium and Steel Wire

2017 ◽  
Vol 892 ◽  
pp. 89-96 ◽  
Author(s):  
Thorsten Henseler ◽  
Madlen Ullmann ◽  
Grzegorz Korpala ◽  
Klaudia Klimaszewska ◽  
Rudolf Kawalla ◽  
...  
Keyword(s):  
Strain Rate ◽  
Elevated Temperatures ◽  
Steel Wire ◽  
Testing Machine ◽  
Constant Strain Rate ◽  
Strain Curve ◽  
Compression Testing ◽  
Uniaxial Tensile ◽  
Flow Curves ◽  
The Difference

This article demonstrates the difference in the flow curves of an AZ31 magnesium alloy and S235JR structural steel wire caused by non-linear strain rates during uniaxial tensile and compression testing at elevated temperatures. Throughout tensile deformation, the traverse velocity of the testing machine has to be adapted according to the current elongation of the specimen, thus accelerating, to ensure a constant strain rate during the admission of the stress-strain curve. The equivalent is necessary during compression testing, where the traverse velocity of the testing machine needs to decelerate ensuring a constant strain rate. Nevertheless, tensile and compression tests are performed with constant traverse velocity, which lead to divergent flow curves in comparison to deformation controlled traverse velocities. The results of the research show the difference in flow behaviour of magnesium and steel wire, when the temperature and strain rate are varied in conjunction with constant and deformation controlled traverse velocities.

High-Speed Tension Tests at Elevated Temperatures—Parts II and III

1941 ◽  
Vol 8 (2) ◽  
pp. A77-A91
Author(s):  
A. Nadai ◽  
M. J. Manjoine
Keyword(s):  
Strain Rate ◽  
Pure Iron ◽  
High Speed ◽  
Elevated Temperatures ◽  
Testing Machine ◽  
Constant Strain Rate ◽  
Observation Data ◽  
Continuous Increase ◽  
Wide Range ◽  
Plastic Forming

Abstract The authors discuss the results of an investigation on the resistance to plastic forming of several metals over a wide range of rates of deformation at various temperatures. To carry out the tests, two machines were built: One, a high-speed testing machine, was described in Part I of this report; the other, a constant-strain-rate machine, is dealt with in this presentation. The general trend of the test results for aluminum and copper indicates a continuous increase of the yield stresses with the strain rate. The speed relation for pure iron and the iron alloys seems to be much more complicated. The resistance to deformation at a given speed of straining exhibits a minimum and a maximum at certain temperatures. This maximum, known as “blue brittleness,” shifts to higher temperatures with increasing speeds of straining; it appears at 200 C for short-time tension speeds and shifts to 550 C for the high speeds. In the high-speed tests a local temperature rise of 50 C, due to the conversion of the work of deformation into heat, was observed in a specimen of pure iron. At very rapid rates of deformation remarkably high ultimate stresses were found for aluminum and copper when tested at temperatures approaching their melting points. A theory for the necking of a bar, based on the speed law, predicts the observed shapes of broken bars which were drawn down to a point. Observation data are furnished for an evaluation of the forces required for very rapid plastic forming of the metals at high temperatures, particularly through rolling.

Tensile Stress-Strain Curves Modeling of Four Kinds of Solders with Temperature and Rate Dependence

2005 ◽  
Vol 297-300 ◽  
pp. 905-911 ◽  
Author(s):  
Xu Chen ◽  
Li Zhang ◽  
Masao Sakane ◽  
Haruo Nose
Keyword(s):  
Tensile Stress ◽  
Constitutive Model ◽  
Strain Rate ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Strain Rate Range ◽  
Rate Dependence ◽  
Strain Rates ◽  
Stress Strain ◽  
Rate Range

A series of tensile tests at constant strain rate were conducted on tin-lead based solders with different Sn content under wide ranges of temperatures and strain rates. It was shown that the stress-strain relationships had strong temperature- and strain rate- dependence. The parameters of Anand model for four solders were determined. The four solders were 60Sn-40Pb, 40Sn-60Pb, 10Sn-90Pb and 5Sn-95Pb. Anand constitutive model was employed to simulate the stress-strain behaviors of the solders for the temperature range from 313K to 398K and the strain rate range from 0.001%sP -1 P to 2%sP -1 P. The results showed that Anand model can adequately predict the rate- and temperature- related constitutive behaviors at all test temperatures and strain rates.

scholarly journals High Strain-Rate Compressive Properties of Carbon/Epoxy Laminated Composites – Effects of loading direction and temperature

2018 ◽  
Vol 183 ◽  
pp. 02011
Author(s):  
Kenji Nakai ◽  
Tsubasa Fukushima ◽  
Takashi Yokoyama ◽  
Kazuo Arakawa
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Slenderness Ratio ◽  
Testing Machine ◽  
Negative Temperature ◽  
Hopkinson Pressure Bar ◽  
Instron Testing Machine

The high strain-rate compressive characteristics of a cross-ply carbon/epoxy laminated composite in the three principal material directions or fibre (1-), in-plane transverse (2-) and throughthickness (3-) directions are investigated on the conventional split Hopkinson pressure bar (SHPB) over a range of temperatures between 20 and 80 °C. A nearly 10 mm thick cross-ply carbon/epoxy composite laminate fabricated using vacuum assisted resin transfer molding (VaRTM) was tested. Cylindrical specimens with a slenderness ratio (= length/diameter) of 0.5 are used in high strain-rate tests, and those with the slenderness ratios of 1.0 and 1.5 are used in low and intermediate strain-rate tests. The uniaxial compressive stress-strain curves up to failure at quasi-static and intermediate strain rates are measured on an Instron testing machine at elevated temperatures. A pair of steel rings is attached to both ends of the cylindrical specimens to prevent premature end crushing in the 1-and 2-direction tests on the Instron testing machine. It is shown that the ultimate compressive strength (or failure stress) exhibits positive strainrate effects and negative temperature ones over a strain-rate range of 10–3 to 103/s and a temperature range of 20 to 80 °C in the three principal material directions.

A variable-order viscoelastic constitutive model under constant strain rate

2020 ◽  
Author(s):  
Yao Wang ◽  
Dagang Sun ◽  
Zhanlong Li ◽  
Yuan Qin ◽  
Bao Sun
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Fractional Order ◽  
Viscoelastic Material ◽  
Constitutive Models ◽  
Constant Strain Rate ◽  
Variable Order ◽  
Hyper Elastic ◽  
Material Coefficient ◽  
Viscoelastic Coefficient

The traditional viscoelastic constitutive models encounter the problems of massive parameters and ambiguous physical meanings. A new concept of variable-order viscoelastic constitutive (called VOVC) model is put forward based on the constant fractional-order constitutive model and the viscoelastic theory. The determination methods of the two parameters in the VOVC model, including the material coefficient and the viscoelastic coefficient, are discussed both in the tensile and the resilient processes. The comparisons are made between the VOVC model and the traditional constitutive models i.e. the constant fractional-order Kelvin-Voigt (CFKV) model, the Zhu-wang-tang nonlinear thermo-viscoelastic constitutive (ZWT) model and the Ogden nonlinear hyper-elastic (Ogden) model. The results show that the VOVC model with the constant material coefficient and the variable viscoelastic coefficient predicts the whole evolution of the constitutive behavior of the viscoelastic material under the constant strain rate more precisely. The constant material coefficient in the VOVC model means the stiffness of the viscoelastic material. The variable viscoelastic coefficient in the model means the distribution of the elasticity and viscosity. The VOVC model contains a simpler structure, fewer parameters, clearer physical meanings and higher precision.

Flow Behavior of Ultra-High Strength Boron Steel at Elevated Temperature

2011 ◽  
Vol 704-705 ◽  
pp. 191-195
Author(s):  
Jun Bao ◽  
Hong Sheng Liu ◽  
Zhong Wen Xing ◽  
Bao Yu Song ◽  
Yu Ying Yang
Keyword(s):  
Elevated Temperature ◽  
Strain Rate ◽  
Flow Behavior ◽  
Hot Stamping ◽  
Testing Machine ◽  
High Strength ◽  
Mathematic Model ◽  
Boron Steel ◽  
Stress Strain ◽  
Simulation Testing

Ultra-high strength boron steel is widely used in a new hot stamping technology which is hot formed and die quenched simultaneously in order to obtain stamping parts with 1500MPa tensile strength or higher. Tensile experiments were carried out with ultra-high strength boron steel in a range of temperature 500°C~860°Cand strain rate 0.01/s~1/s with the thermal simulation testing machine Gleeble 3800, and the stress-strain curves were obtained. The influences of the deformation temperature and strain rate on the stress-strain curves were analyzed. The results show that hot behavior at elevated temperature of ultra-high strength boron steel consists of strain hardening and dynamic recovery mechanism, which can be accurately described by the mathematic model. Keywords: Ultra-high strength boron steel, hot stamping, hot flow behavior

Influence of Ti on the Hot Ductility of High-manganese Austenitic Steels

2017 ◽  
Vol 36 (7) ◽  
pp. 725-732
Author(s):  
Hongbo Liu ◽  
Jianhua Liu ◽  
Bowei Wu ◽  
Xiaofeng Su ◽  
Shiqi Li ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Austenitic Steel ◽  
Testing Machine ◽  
Constant Strain Rate ◽  
Austenitic Steels ◽  
Hot Ductility ◽  
High Manganese ◽  
Thermo Calc Software ◽  
Simulation Testing ◽  
Ti Addition

AbstractThe influence of Ti addition (~0.10 wt%) on hot ductility of as-cast high-manganese austenitic steels has been examined over the temperature range 650–1,250 °C under a constant strain rate of 10−3 s−1 using Gleeble3500 thermal simulation testing machine. The fracture surfaces and particles precipitated at different tensile temperatures were characterized by means of scanning electron microscope and X-ray energy dispersive spectrometry (SEM–EDS). Hot ductility as a function of reduction curves shows that adding 0.10 wt% Ti made the ductility worse in the almost entire range of testing temperatures. The phases’ equilibrium diagrams of precipitates in Ti-bearing high-Mn austenitic steel were calculated by the Thermo-Calc software. The calculation result shows that 0.1 wt% Ti addition would cause Ti(C,N) precipitated at 1,499 °C, which is higher than the liquidus temperature of high-Mn austenitic steel. It indicated that Ti(C,N) particles start forming in the liquid high-Mn austenitic steel. The SEM–EDS results show that Ti(C,N) and TiC particles could be found along the austenite grain boundaries or at triple junction, and they would accelerate the extension of the cracks along the grain boundaries.

Parameter Evaluation for a Unified Constitutive Model

1993 ◽  
Vol 115 (2) ◽  
pp. 157-162 ◽  
Author(s):  
P. E. Senseny ◽  
N. S. Brodsky ◽  
K. L. DeVries
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Least Squares ◽  
Constitutive Equations ◽  
Laboratory Data ◽  
Constant Strain Rate ◽  
Nonlinear Least Squares ◽  
Evolutionary Equation ◽  
Internal Variables ◽  
Isotropic Hardening

Parameters for the unified constitutive model MATMOD [1] were evaluated for rock salt (NaCl) by using nonlinear least squares to fit the model to isothermal laboratory data. MATMOD incorporates two internal variables that represent the effects of both kinematic and isotropic hardening. The constitutive equations contain nine parameters that must be evaluated to model isothermal deformation. Laboratory data from stress relaxation, constant strain rate, and long-term creep tests were used. The latter two test types included staged tests in which the strain rate or stress was changed step-wise during the test. The test conditions were precisely controlled by a computer and the constitutive equations were integrated to simulate the laboratory conditions closely. The MATMOD parameters were then evaluated by fitting the integrated equations to the laboratory data using nonlinear least squares. The model fits the data well, but the fit may be improved by changing the evolutionary equation for the internal variable that accounts for isotropic hardening.

Tensile Behaviour of Al5052 Alloy Sheets Annealed at Different Temperatures

2013 ◽  
Vol 845 ◽  
pp. 431-435 ◽  
Author(s):  
V Mugendiran ◽  
A. Gnanavelbabu ◽  
R Ramadoss
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Sheet Metal ◽  
Tensile Testing ◽  
Elevated Temperatures ◽  
Testing Machine ◽  
Constant Strain Rate ◽  
Tensile Behaviour ◽  
Increase With Increase

With recent development in automotive industries, aluminium alloys have great demand in sheet metal fabrication industries. Sheet metal forming at slightly elevated temperatures is more acceptable in forming operations. The mechanical properties such as yield strength, ultimate tensile strength and percentage of elongation are very influential in determining the formability of sheet metals in various applications. In this paper, tensile property of Al5052 alloy is investigated at constant strain rate under different annealing conditions from room to 350°C. Servo controlled universal testing machine was used for tensile testing. The results of tensile testing indicate that the tensile properties including yield strength, ultimate tensile strength decreases and elongation percentage increases with the increase in annealing temperature. The analysis shows that the formability parameters, strain hardening index and strength coefficient increase with increase in annealing temperatures.

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