Compression Behavior of L12 Modified Titanium Trialuminides Alloyed with Chromium and Iron

2000 ◽  
Vol 646 ◽  
Author(s):  
Tohru Takahashi ◽  
Tadashi Hasegawa
Keyword(s):  
Steady State ◽  
Flow Stress ◽  
Chemical Composition ◽  
Single Phase ◽  
Strain Softening ◽  
Lattice Parameter ◽  
Quasi Steady State ◽  
Compression Tests ◽  
Steady State Flow ◽  
Compression Behavior

ABSTRACTL12 modified titanium trialuminides have been prepared by replacing 9at.% of the aluminum in Al3Ti with chromium and/or iron. The materials were recrystallized into single phase polycrystals after isothermal forging resulting in an average grain diameter of about 40μm. Lattice parameter of the material containing 9 at.% chromium or 9 at.% iron, are 0.3959nm and 0.3939nm, respectively. The lattice parameters varied linearly with composition between these values for additions of both chromium and iron. Uniaxial compression tests were performed at temperatures ranging from 293K to 1300K. The yield strength is not sensitive to chemical composition within the range of compositions tested. Flow stress serrations of a few % were observed at temperatures around 600K, where intermittent drops in flow stress started immediately after yielding and continued to the end. These serrations were observed up to about 800K. At 900K and above the materials became fully deformable. Quasi steady state flow and strain softening were observed at 1200K and 1300K, respectively, due to dynamic recrystallization.

A Graphical Method for Storage Coefficient Determination from Quasi-Steady State Flow Data

1996 ◽  
Vol 27 (4) ◽  
pp. 247-254 ◽  
Author(s):  
Zekâi Şen
Keyword(s):  
Steady State ◽  
Graphical Method ◽  
Pumping Test ◽  
Quasi Steady State ◽  
Flow Data ◽  
Steady State Flow ◽  
Storage Coefficient ◽  
State Flow ◽  
Aquifer Test

A simple, approximate but practical graphical method is proposed for estimating the storage coefficient independently from the transmissivity value, provided that quasi-steady state flow data are available from a pumping test. In the past, quasi-steady state flow distance-drawdown data have been used for the determination of transmissivity only. The method is applicable to confined and leaky aquifers. The application of the method has been performed for various aquifer test data available in the groundwater literature. The results are within the practical limits of approximation compared with the unsteady state flow solutions.

High-Temperature Mechanical Behavior of B2 Type IrAl Doped With Ni

1996 ◽  
Vol 460 ◽  
Author(s):  
A. Chiba ◽  
T. Ono ◽  
X. G. Li ◽  
S. Takahashi
Keyword(s):  
Steady State ◽  
Mechanical Behavior ◽  
Constant Velocity ◽  
Single Phase ◽  
Elevated Temperatures ◽  
Constant Load ◽  
Secondary Creep ◽  
Compression Tests ◽  
Order Of Magnitude ◽  
Multi Phase

ABSTRACTConstant-velocity and constant-load compression tests have been conducted to examine the mechanical behavior of polycrystalline IrAl and Ir1-xNixAl at ambient and elevated temperatures. Although IrAl exhibits brittle fracture before or immediately after yielding below 1073K, steady-state deformation takes place at temperatures higher than 1273K. Ductility of Ir1-xNixAl is improved with increasing x. On the contrary, strength decreases with increasing x. IrAl exhibits the 0.2% flow stress of 1200MPa at 1073K and 350MPa at 1473K, about an order of magnitude higher than NiAl. Secondary creep of IrAl and Ir0.2Ni0.8Al(i.e., modified NiAl) exhibits class II and class I behavior respectively. Creep strength of binary IrAl and modified NiAl with Ir is about a magnitude of 4 higher than that of single-phase and multi-phase NiAl at a given applied stress.

Investigation of Flow Stress Behavior and Microstructural Evolution of 7050 Al Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 1065-1068 ◽  
Author(s):  
You Ping Yi ◽  
Hua Chen ◽  
Yong Cheng Lin
Keyword(s):  
Steady State ◽  
Strain Softening ◽  
Type Equation ◽  
Al Alloy ◽  
Compression Tests ◽  
Hollomon Parameter ◽  
Deformation Behaviors ◽  
Three Stages ◽  
Increasing Temperature ◽  
State Stress

The plastic deformation behaviors of 7050 Al alloy were investigated by compression tests at temperatures ranging of 250°C450°C under constant strain rates of 0.01s−1, 1s−1 and 10s−1. The results showed that all the flow curves consisted of three stages, i.e. strain-hardening, strain-softening and steady state-strain. Initially, the stress rises steeply at microstrain deformation, and then increases at a decreased rate, followed by a strain-softening until a steady state stress. The stress level decreases with increasing deformation temperature and decreasing strain rate, which can be represented by a Zener-Hollomon parameter in an exponent-type equation, 1 19 7.202 σ p 80.71 sinh (1.64 10 Z) = ⋅ −  × − ⋅ −  . Elongated grains with serrations developed in the grain boundaries were observed; the dynamic recrystallization (DRX) occurs with increasing temperature and dislocation density, and the shape of grain at steady state is nearly equiaxial. It can be concluded that the DRX phenomenon is sensitive to the temperature and the dynamic flow softening is mainly as the result of dynamic recovery and DRX.

Piping Fluid Transients Made Simple: Part I — Theory of the SSFFC Methodology

2005 ◽  
Author(s):  
Zakaria N. Ibrahim
Keyword(s):  
Fluid Flow ◽  
Steady State ◽  
Fluid Pressure ◽  
Piping System ◽  
Consecutive Series ◽  
Quasi Steady State ◽  
Sound Waves ◽  
Steady State Flow ◽  
State Flow ◽  
Pipe Segment

Piping systems transporting fluid between plant components are subjected to a variety of anticipated and/or postulated flow changes that disturb their steady state operations. These changes cause the fluid flow to accelerate and/or decelerate. However, consideration of fluid elasticity transforms these disturbances into weak and/or strong propagating sound waves, depending upon the abruptness level of the fluid state change. This generates dynamic forces on the pipe segments of the piping system. A simple concept for understanding the piping fluid transient phenomenon from its physical perspective is presented. The piping system consists of several pipe segments, each segment having a constant cross-sectional flow area. The pipe segment is further divided into a consecutive series of zones. Each zone comprises two or three sub-zones of quasi steady state flow. The sub-zones are separated by interface fronts at which the jump in fluid pressure and velocity occurs across them. These fronts propagate and clash with each other to create the next temporal set of sub-zones quasi steady state flow. This method is denoted in this paper as steady state flow fronts clashing ‘SSFFC’. Clashing between the incident, transmitted and/or reflected wave fronts within the zone is introduced. As a precursor to the second part of a two-part publication, the SSFFC is physically illustrated and mathematically formulated to establish the temporal fluid steady state contained within each sub-zone constituting the pipe segment. The developed formulations are comparable to those instituted by the conventional method of characteristics. The pipe segment generalized fluid flow transient forces based on SSFFC methodology are also formulated. In the concurrent publication that forms part two of this presentation [8], sample applications of SSFFC methodology are illustrated.

scholarly journals Design of an Analog Quasi-Steady-State Nonlinear Current-Mode Controller for Single-Phase Active Power Filter

2009 ◽  
Vol 56 (12) ◽  
pp. 4872-4881 ◽  
Author(s):  
J. Miret ◽  
L. Garcia de Vicuna ◽  
M. Castilla ◽  
J. Matas ◽  
J.M. Guerrero
Keyword(s):  
Steady State ◽  
Single Phase ◽  
Active Power Filter ◽  
Current Mode ◽  
Active Power ◽  
Quasi Steady State ◽  
Power Filter

scholarly journals On the application of storage coefficient determination by quasi-steady-state flow

2005 ◽  
Vol 36 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Mehmet E. Birpinar ◽  
Ayhan Gazioglu
Keyword(s):  
Steady State ◽  
Quasi Steady State ◽  
Confined Aquifer ◽  
Steady State Flow ◽  
Steady State Condition ◽  
Storage Coefficient ◽  
Unconfined Aquifers ◽  
Aquifer Test ◽  
Order Of Magnitude ◽  
Observation Wells

A simple analytical method has been used for estimating the storage coefficient provided that transmissivity of the aquifer is known at the quasi-steady-state condition in confined or unconfined aquifers. The application of the method has been performed for unconfined and confined aquifer test data in Chaj Doab, Pakistan with observation wells and compared with conventional methods in the groundwater flow literature dealing with pumping tests. The results from the methodology presented in this paper conform well in practice with the results obtained from the traditional methods on the basis of order of magnitude.

scholarly journals Analytical Descriptions of Dynamic Softening Mechanisms for Ti-13Nb-13Zr Biomedical Alloy in Single Phase and Two Phase Regions

2017 ◽  
Vol 62 (4) ◽  
pp. 2029-2043
Author(s):  
G.-Z. Quan ◽  
X. Wang ◽  
Y.-L. Li ◽  
L. Zhang
Keyword(s):  
Flow Stress ◽  
Kinetic Model ◽  
Strain Rate ◽  
Single Phase ◽  
Dual Phase ◽  
Compression Tests ◽  
Two Phase ◽  
Softening Mechanism ◽  
Wide Range ◽  
Dynamic Softening

AbstractDynamic softening behaviors of a promising biomedical Ti-13Nb-13Zr alloy under hot deformation conditions across dual phaseα+βand single phaseβregions were quantitatively characterized by establishing corresponding dynamic recovery (DRV) and dynamic recrystallization (DRX) kinetic models. A series of wide range hot compression tests on a Gleeble-3500 thermo-mechanical physical simulator were implemented under the strain rate range of 0.01-10 s−1and the temperature range of 923-1173 K. The apparent differences of flow stress curves obtained in dual phaseα+βand single phaseβregions were analyzed in term of different dependence of flow stress to temperature and strain rate and different microstructural evolutions. Two typical softening mechanisms about DRV and DRX were identified through the variations of a series of stress-strain curves acquired from these compression tests. DRX is the dominant softening mechanism in dual phaseα+βrange, while DRV is the main softening mechanism in single phaseβrange. The DRV kinetic model for single phaseβregion and the DRX kinetic model for dual phaseα+βregion were established respectively. In addition, the microstructures of the compressed specimens were observed validating the softening mechanisms accordingly.

High-Temperature Deformation of Yba2Cu307-8 With Ag Additions

1989 ◽  
Vol 169 ◽  
Author(s):  
J.L. Routbort ◽  
K.C. Goretta ◽  
J.P. Singh
Keyword(s):  
Activation Energy ◽  
Steady State ◽  
High Temperature ◽  
Flow Stress ◽  
Compressive Strain ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Steady State Flow ◽  
Ag Additions

AbstractThe steady‐state flow stress of YBa2Cu3O7‐δ containing 15 to 30 vol.% Ag has been measured in air at nearly constant compressive strain rates between 5 x 10‐6 and 1 x 10‐4 s‐1 from 830 to 900°C. Addition of Ag dramatically decreases the flow stress compared to that of the pure superconductor, but the stress exponents and the activation energy for deformation remain unchanged.

scholarly journals Establishment of Prediction Model of Microstructure and Properties of 3003 Aluminum Alloy during Hot Deformation

2019 ◽  
Vol 25 (4) ◽  
pp. 369-375 ◽  
Author(s):  
Guiqing CHEN ◽  
Gaosheng FU ◽  
Tianyun WEI ◽  
Chaozeng CHENG ◽  
Huosheng WANG ◽  
...  
Keyword(s):  
Grain Size ◽  
Aluminum Alloy ◽  
Steady State ◽  
Flow Stress ◽  
Prediction Model ◽  
Hot Deformation ◽  
Steady State Flow ◽  
State Flow ◽  
Average Grain Size ◽  
The Relationship

The 3003 aluminum alloy was deformed by isothermal compression in the range of deformation temperature 300 – 500 ℃ at strain rate 0.0l – 10.0 s-1 with Gleeble-1500 thermal simulator. A constitutive equation is established from the flow stress of the hot deformation. It is found that the average grain size of the 3003 aluminum alloy increases with the decrease of Zener-Hollomon (Z) value, and there is a linear correlation between them. The prediction model of the steady-state flow stress and the average grain size is established. The steady-state flow stress increases with the decrease of the average grain size. The microhardness of the 3003 aluminum alloy has a positive linear relationship with lnZ, and the relationship between the microhardness and the grain size meets the Hall-Petch equation, which can provide a reference for the microstructure control and rolling equipment selection of the 3003 aluminum alloy under hot deformation conditions.

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