The effect of strain rate on the plastic flow characteristics of steel and aluminium sheet

1966 ◽  
Vol 1 (5) ◽  
pp. 439-446 ◽  
Author(s):  
A N Bramley ◽  
P B Mellor
Keyword(s):  
Strain Rate ◽  
Uniaxial Tension ◽  
Plastic Flow ◽  
Work Hardening ◽  
Sheet Steel ◽  
Flow Characteristics ◽  
Strain Rates ◽  
Plastic Strains ◽  
Aluminium Sheet

Work-hardening characteristics for sheet steel and aluminium have been obtained experimentally over a range of strain rates from 10−4 to 102/s. Use of the diaphragm test enables work-hardening characteristics to be obtained to much higher plastic strains than is possible in uniaxial tension. Results for killed steel show that the slope of the work-hardening characteristics decreases with increase in strain rate. Tentative extrapolation of the results suggests that if similar tests could be carried out at a strain rate of 104 then the work hardening characteristic would be that of an ideally plastic solid. In the case of aluminium the above phenomenon is not so marked and it is not possible to make even a tentative extrapolation to higher strain rates.

A State Variable Modeling of Plasticity and Necking Under Uniaxial Tension

1992 ◽  
Vol 114 (4) ◽  
pp. 378-383 ◽  
Author(s):  
G. Ferron ◽  
H. Karmaoui Idrissi ◽  
A. Zeghloul
Keyword(s):  
Strain Rate ◽  
Uniaxial Tension ◽  
Plastic Flow ◽  
Constitutive Equations ◽  
Growth Process ◽  
Constant Strain Rate ◽  
Uniaxial Tensile ◽  
Long Wavelength ◽  
State Variable ◽  
Diffusion Controlled

Constitutive equations based on a state variable modeling of the thermo-viscoplastic behavior of metals are discussed, and incorporated in an exact, long-wavelength analysis of the neck-growth process in uniaxial tension. The general formalism is specialized to the case of f.c.c. metals in the range of intragranular, diffusion controlled plastic flow. The model is shown to provide a consistent account of aluminum behavior both under constant strain-rate and creep. Calculated uniaxial tensile ductilities and rupture lives in creep are also compared with experiments.

Effect of Hot Extrusion on the Flow Behaviour of a Nickel-Based P/M Superalloy

2019 ◽  
Vol 298 ◽  
pp. 43-51
Author(s):  
Jia Yong Si ◽  
Song Hao Liu ◽  
Long Chen
Keyword(s):  
Activation Energy ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Work Hardening ◽  
Rate Sensitivity ◽  
Hot Extrusion ◽  
Turbine Disk ◽  
Flow Behaviour ◽  
Strain Rates ◽  
Work Hardening Rate

This research investigated the effect of hot extrusion on the flow behaviour of nickel-based superalloy FGH4096 by hot compression experiments in the temperature range from 1020 to 1110 °C and strain rates ranging from 0.1 to 0.001 s-1. The influence of the hot extrusion on the initial microstructures, work hardening rate, strain rate sensitivity, and activation energy of deformation were discussed. The results show that the extruded microstructure is constituted by the fine dynamic recrystallisation of grains. The true strain-true stress curves show that the as-HIPed and as-HEXed FGH4096 superalloy present double flow stress peaks and discontinuous flow softening. The as-HEXed FGH4096 is easily dynamically softened at high temperatures and high strain rates compared with as-HIPed microstructures. As for the work hardening rate, the as-HEXed FGH4096 exhibits higher θ values than that of as-HIPed. It is beneficial to the homogenous deformation and grain refinement during subsequent turbine disk forging. Comparing to as-HIPed FGH4096, the highest strain rate sensitivity value of as-HEXed is 0.306 at 1110 °C. The isothermal superplastic forging of a P/M turbine disk may be carried out at this temperature. The deformation activation energy value of the as-HIPed FGH4096 is lower which means that dislocation sliding and climbing can be easily initiated in the as-HIPed alloy.

Deformation and Fracture of a Silicate Melt Around Tg: Implications to Dynamics of Volcanic Eruptions

2008 ◽  
Author(s):  
Mie Ichihara ◽  
Daniel Rittel ◽  
M. B. Rubin
Keyword(s):  
Strain Rate ◽  
Work Hardening ◽  
High Strain ◽  
Elastic Solid ◽  
Volcanic Eruptions ◽  
Strain Rates ◽  
Stress Strain Relation ◽  
Deformation And Fracture ◽  
Fracture Transition ◽  
Low Strain Rate

The mechanical properties of magma around the glass transition temperature have not been characterized yet, though this subject is considered to be important in dynamics of volcanic eruptions. In this paper, we present an experimental investigation of stress-strain relation of synthetic magma at various temperatures and strain rates. The material behaves as an elastic solid at low temperature and/or high strain rate, and as a viscous fluid at high temperature and/or low strain rate. In the transition, it reveals work-hardening response. Although the work-hardening nature has not been reported for noncrystalline magma, it is important in constructing a mathematical model to represent the flow-to-fracture transition of magma, namely the transition of eruptions from effusive to explosive styles.

scholarly journals Strain-Rate-Dependent Tensile Response of Ti–5Al–2.5Sn Alloy

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 659 ◽  
Author(s):  
Bin Zhang ◽  
Jin Wang ◽  
Yang Wang ◽  
Yu Wang ◽  
Ziran Li
Keyword(s):  
Strain Rate ◽  
Strain Hardening ◽  
Uniaxial Tension ◽  
Temperature Rise ◽  
High Strain ◽  
Adiabatic Temperature ◽  
High Rate ◽  
Strain Rates ◽  
High Strain Rates ◽  
Adiabatic Temperature Rise

This study is an experimental investigation on the tensile responses of Ti–5Al–2.5Sn alloy over a wide range of strain rates. Uniaxial tension tests within the rate range of 10−3–101 s−1 are performed using a hydraulic driven MTS810 machine and a moderate strain-rate testing system. The high-rate uniaxial tension and tension recovery tests are conducted using a split-Hopkinson tension bar to obtain the adiabatic and isothermal stress–strain responses of the alloy under dynamic loading conditions. The experimental results show that the value of the initial yield stress increases with the increasing strain rate, while the strain rate sensitivity is greater at high strain rates. The isothermal strain-hardening behavior changes little with the strain rate, and the adiabatic temperature rise is the main reason for the reduction of the strain-hardening rate during high strain-rate tension. The electron backscatter diffraction (EBSD) analysis of the post-deformed samples indicates that there are deformation twins under quasi-static and high-rate tensile loadings. Scanning electron microscope (SEM) micrographs of the fracture surfaces of the post-deformed samples show dimple-like features. The Zerilli–Armstrong model is modified to incorporate the thermal-softening effect of the adiabatic temperature rise at high strain rates and describe the tension responses of Ti–5Al–2.5Sn alloy over strain rates from quasi-static to 1050 s−1.

scholarly journals The Temperature and Strain Rate Dependence of the Flow Stress of Single Crystal Nial Deformed Along

1994 ◽  
Vol 364 ◽  
Author(s):  
Stuart A Maloy ◽  
George T Gray
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Single Crystal ◽  
Work Hardening ◽  
Rate Dependence ◽  
Temperature Sensitive ◽  
Strain Rates ◽  
Slip Bands ◽  
Work Hardening Rate ◽  
Slip Traces

AbstractSingle crystal NiAl and Ni-49.75Al-0.25Fe have been deformed along <110> at temperatures of 77, 298 and 773K and strain rates of 0.001/s, 0.1/s and 2000/s. The flow stress of <110> NiAl is rate and temperature sensitive. A significant decrease in the work hardening rate is observed after deformation at 77K and a strain rate of 2000/s. Coarse {110} slip traces are observed after deformation at a strain rate of 2000/s at 77K, while no slip traces were observed after deformation under all other conditions. TEM observations reveal distinct {110} slip bands after deformation at 77K and a strain rate of 2000/s.

A Mechanical Model for TRIP Sheet Steel Forming

2011 ◽  
Vol 221 ◽  
pp. 21-26
Author(s):  
Ti Kun Shan ◽  
Li Liu
Keyword(s):  
Constitutive Equation ◽  
Strain Hardening ◽  
Uniaxial Tension ◽  
Work Hardening ◽  
Trip Steel ◽  
Mechanical Model ◽  
Sheet Steel ◽  
Stress Triaxiality ◽  
Transformation Rate ◽  
Stress Strain Relation

An enhanced elastic-plastic constitutive equation taking into account strain induced transformation and its effect on work hardening of TRIP steel during deformation are investigated. The transformation rate relies on the stress triaxiality. The strain hardening of the TRIP steel takes on parabola shape because of the austenite changed to the martensite during straining. The physical model is verified by comparing with the stress-strain relation of the uniaxial tension experiment. The results showed that the steel keeps a high hardening potential which retards the onset of necking and a good formability thanks to the martensitic strain-induced transformation and the subsequent austenite hardening.

Influence of Strain Rate and Stress State on the Mechanical Behavior of Die-Casting AM60 Magnesium Alloy

2011 ◽  
Author(s):  
Gongyao Gu ◽  
Shaoting Lin ◽  
Yan Meng ◽  
Yong Xia ◽  
Qing Zhou
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Uniaxial Tension ◽  
Fracture Strain ◽  
Yield Criterion ◽  
Die Casting ◽  
Test Method ◽  
Strain Rates ◽  
Tension And Compression ◽  
Von Mises

This paper presents experimental study, including the test method and the test data analysis, on the die-casting AM60 magnesium alloy material. Uniaxial tension tests were carried out at various strain rates roughly from 5 × 10−4 to 1 × 102 s−1, which are of interest in vehicle crash CAE. Uniaxial compression and shear tests at strain rates from 5 × 10−4 to 5 × 10−2 s−1 were also carried out. All the specimens were cut off from die-casting plates of AM60 with thickness of 2.6 mm. The test results show that the yield stress of die-casting AM60 increases slightly with the strain rate at uniaxial tension. However, this tendency is not very significant due to the relatively large variation among the tests. There is no obvious relationship between the fracture strain and the strain rate at uniaxial tension and compression. For shear, the fracture strain decreases with higher strain rate. It is verified that this material follows the von-Mises yield criterion, with nearly symmetrical yielding behavior between uniaxial tension and compression at the same level of strain rates. And it is shown that the equivalent fracture strain or effective ultimate strength at uniaxial tension and shear states is relatively close to each other, which is significantly smaller than those at compression. According to these results, it is necessary to perform further study with additional tests at other stress states for accurately characterizing the fracture behavior of the die-casting AM60 magnesium alloy.

Strain Rate Sensitivity, Strain Hardening, and Yield Behavior of 304L Stainless Steel

1986 ◽  
Vol 108 (4) ◽  
pp. 344-353 ◽  
Author(s):  
M. G. Stout ◽  
P. S. Follansbee
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Strain Hardening ◽  
Strain Rate Sensitivity ◽  
Work Hardening ◽  
Rate Sensitivity ◽  
Yield Locus ◽  
304L Stainless Steel ◽  
Strain Rates ◽  
Yield Behavior

Sheet and rod stock of 304L stainless steel were tested in uniaxial tension and compression at strain rates between 10−4 s−1 and 104 s−1. To evaluate the yield locus behavior of the sheet material, multiaxial experiments were performed at a strain rate of 10−3 s−1. We have analyzed these results in terms of existing strain-rate sensitivity, work hardening, and yield locus models. Strain-rate sensitivity was found to follow a thermal activation law over the entire range of strain rates used in this investigation. The best description of strain hardening did depend on the strain range to which the data were fit. The Voce law was the most accurate at large strains (ε > 0.40), whereas at small strains, in the vicinity of yield, the laws of either Swift or Ludwik were the most accurate. A simple power law description of work hardening was inadequate over all levels of strain. We examined a number of yield criteria, both isotropic and anisotropic, with respect to the biaxial yield behavior. Bassani’s yield criterion gave the best fit to our experimental results. However, the simple von Mises yield function also gave an acceptable prediction of yield strength and direction of current plastic strain rate. The yield criteria of Hill, both the quadratic and nonquadratic versions, did not match the experimental data. We feel that these results have direct application to the selection of the proper constitutive laws for the finite element modeling of the deformation of 304L stainless steel.

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