Modelling of Flow Behaviour of Magnesium Alloys

2016 ◽  
Vol 716 ◽  
pp. 360-367
Author(s):  
Carlo Bruni
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Low Temperature ◽  
Magnesium Alloys ◽  
Flow Curve ◽  
Flow Behaviour ◽  
Temperature Deformation ◽  
Flow Curves ◽  
High Deformation ◽  
Modelling Approach

The present investigation aims at studying the flow behaviour of magnesium alloys under different conditions in terms of temperature, deformation velocities and deformation. The modelling approach was based on a proposed equation to model the shape of each flow curve through different variables. The modelled flow curves were subsequently compared with those obtained with experiments. The models were validated on flow curves not used in the building stage. It was observed that, for low temperature values, high deformation velocities and deformations the final part of the flow curve has to be adapted in order to be adopted for the description of material in the numerical simulation. In other words it needs to be extrapolated. Also for the high temperature, the flow softening has to be limited in order to allow the extrapolation queue required for elevated deformations. The deformation value at which the extrapolation can start can be predicted with an other proposed equation detailed in the paper.

scholarly journals Numerical Simulation and Design of a High-Temperature, High-Pressure Fluid Transport Pipe

2020 ◽  
Vol 10 (17) ◽  
pp. 5890
Author(s):  
Jiyoung Yoon ◽  
Junkyu Park ◽  
Jinhyoung Park
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
High Pressure ◽  
High Temperature ◽  
Low Temperature ◽  
Fluid Transport ◽  
Projectile Velocity ◽  
Gas Leakage ◽  
And Performance ◽  
High Temperature High Pressure

When designing a hand caliber with a high-temperature, high-pressure internal fluid transport pipe, reliability, safe use, and performance must be considered. Reliability refers to the stress caused by thermo-mechanical load; safe use refers to the low-temperature burns that might occur upon contact, and high-temperature burns caused by gas leakage occurring in the cylinder gap; and performance refers to projectile velocity. In this study, numerical simulation methods for heat transfer, structure analysis, and gas leakage are proposed so that solutions can be designed to account for the above three criteria. Furthermore, a hand-caliber design guide is presented. For heat transfer and structural analysis, mesh size, the transient convective heat transfer coefficient, and boundary conditions are described. Regarding gas leakage, methods reflecting projectile motion and determination of the molecular weight of the propellant are described. As a result, a designed hand caliber will have a high reliability, because the thermo-mechanical stress is lower than the yield stress. There will be little risk of low-temperature burns, but there will be a high temperature-burn risk, owing to gas leakage in the cylinder gap. The larger the cylinder-gap size, the greater the gas leakage and the smaller projectile velocity. The presented numerical simulation method can be applied to evaluate various aspects of other structures that require high-temperature, high-pressure fluid-transport pipes.

Low Temperature Deformation Kinetics of Ruthenium Aluminide Alloys

1998 ◽  
Vol 552 ◽  
Author(s):  
D. C. Lu ◽  
T. M. Pollock
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Strain Rate ◽  
Rate Change ◽  
The Other ◽  
Temperature Deformation ◽  
Strain Rate Change ◽  
Deformation Kinetics ◽  
Ruthenium Aluminide ◽  
Kinetics Of

ABSTRACTThe kinetics of low temperature deformation were investigated in several different polycrystalline RuAl alloys with the use of strain rate change experiments at 77 K and 298 K. Compositions investigated include RuAl, RuAl+0.5%B, Ru51.5 A48.5, Ru52 Al48, RU53 A147+0.5%B, Ru54.5 Al45.5, and Ru52 Al43 Sc5. Flow stresses did not vary substantially with temperature between 77 K and 298 K. Rate sensitivities were low compared to other B2 compounds and similar in all compositions investigated. Analyses of dislocation substructures after low strain deformation were conducted. The deformation kinetics and substructural observations suggest a higher intrinsic deformability for RuAI alloys with respect to the other high temperature B2 aluminides.

Insights into chemical mobility in titanite driven by low-temperature crystal-plastic deformation

2021 ◽  
Author(s):  
Nicholas Udy ◽  
Michael Stearns
Keyword(s):  
Plastic Deformation ◽  
High Temperature ◽  
Low Temperature ◽  
Crystal Lattice ◽  
Trace Element ◽  
Fault Zone ◽  
Temperature Deformation ◽  
Icp Ms ◽  
Trace Element Contents ◽  
Element Contents

<p>The U-Pb system in titanite has been shown to be reset during a variety of high-temperature processes including high-temperature deformation, but post-deformation modification and recovery of crystal-lattice strain have so far made U-Pb equilibration mechanism from deformed titanites equivocal. Microstructures, including mechanical twinning and subgrain rotation recrystallization are more likely to be preserved at low-temperatures, but the systematics of chemical equilibration have not been established for these conditions. This study identifies progressive crystallographic misorientation and deformation twins in titanite porphyroclasts from the Wasatch Fault Zone, Utah, USA. The microstructures, mapped using electron backscatter diffraction (EBSD), developed at ~11 km depth during 300–400 ºC crystal-plastic deformation within the ductile fault zone. These microstructural maps were used to guide laser ablation-split stream ICP-MS analysis: U-Pb isotopes measured in tandem with major and trace element contents. Despite the low temperature, U-Pb and trace element contents in titanite equilibrated, at least partially, during deformation. Both major and trace elements in titanite also likely partitioned with a fluid and in response to the (re)crystallization of other mineral phases in the fault zone. Chemical zoning and crystal lattice recovery suggestive of fluid-aided recrystallization are absent, and the main mechanism for this resetting may instead be an enhancement of element mobility along microstructure dislocations. These processes are interpreted to record complex open-system behavior of titanite caused by crystal-plastic deformation during the initiation of the WFZ. This presentation will summarize the comparative analysis of microstructure by EBSD and titanite chemistry by LASS-ICP-MS, and how it bears on the understanding of elemental mobility in titanite during low-temperature crystal-plastic deformation.</p>

scholarly journals High Temperature Deformation Behavior of 8090 Al-Li Alloy

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Woo Young Jung ◽  
Tae Kwon Ha
Keyword(s):  
High Temperature ◽  
Deformation Behavior ◽  
Internal Variable ◽  
Grain Boundary Sliding ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Flow Curves ◽  
Variable Theory ◽  
Self Diffusion ◽  
Internal Variable Theory

High temperature deformation behavior, especially the superplasticity of an 8090 Al-Li alloy, was studied within the recent framework of the internal variable theory of structural superplasticity. In this study, a series of load relaxation tests were conducted at various temperatures ranging from 200°C to 530°C to obtain the flow curves of log ε˙versus log ε. The effect of grain size was also examined by varying the grain sizes through a proper thermomechanical treatment. The flow curves were found to be composite curves consisting of contributions from grain boundary sliding (GBS) and grain matrix deformation (GMD) at superplastic temperatures. The activation energy obtained for GMD was 124.9 kJ/mole in the temperature range from 470°C to 530°C, very similar to that for self-diffusion in pure Al.

Characterization of deformation processing maps of 304L stainless steel based on compressive and tensile flow curves

2018 ◽  
Vol 233 (10) ◽  
pp. 3570-3582 ◽  
Author(s):  
Ji Yeong Park ◽  
Il Yeong Oh ◽  
Chester J Van Tyne ◽  
Young Hoon Moon
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Strain Rate ◽  
Processing Map ◽  
Temperature Deformation ◽  
304L Stainless Steel ◽  
Processing Maps ◽  
Compression Tests ◽  
Flow Curves ◽  
Deformation Processing

The efficiency factor (η) and the instability factor ([Formula: see text] in deformation processing maps are regarded as the reliable indices of formability during high-temperature deformation. Deformation processing maps are primarily based on strain rate sensitivity ( m) and are usually created by high-temperature compression tests. To analyze the effect of the mode of flow on the deformation processing map, deformation processing maps based on both compressive and tensile flow curves for 304L stainless steel were determined and compared in the current study. As the instantaneous strain rate varies during both the tensile and compression tests when a constant crosshead speed is used, strain rate compensated deformation processing maps have been determined and compared. In addition, the frictional effect of barreling during compression testing on the deformation processing map has been analyzed. Both deformation processing maps based on either compressive or tensile flow curves are estimated to be complementary.

High Temperature Deformation and Associated 3D Characterisation of Damage in Magnesium Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 1128-1133 ◽  
Author(s):  
Pierre Lhuissier ◽  
A. Villanueva Fernandez ◽  
L. Salvo ◽  
Jean Jacques Blandin
Keyword(s):  
High Temperature ◽  
Magnesium Alloys ◽  
Room Temperature ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
X Ray ◽  
Plastic Stability ◽  
Micro Tomography ◽  
3D Information ◽  
Deformation Tests

A way to overcome the low deformability of magnesium alloys at room temperature is toincrease the temperature of forming operations. The stress exponent n, which is known to be a keyparameter in the control of plastic stability, generally decreases when temperature increases.Nevertheless, low n-values are not enough to ensure large capacity of deformation since fracturecan also result from strain induced cavitation. In the present investigation, both the mechanisms ofhigh temperature deformation and damage were studied in selected Mg alloys. Since damage datacan also give information on the deformation mechanisms, the strain induce cavitation behaviourwas mainly studied thanks to X-ray micro tomography which provides 3D information like thecavity shapes or the variation with strain of the number of cavities. Moreover, additionally toconventional post mortem analyses, it was attempted to perform the 3D damage characterisation inin situ conditions, namely directly during high temperature deformation tests.

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