A threshold stress for high-temperature plastic flow in WC-CO cemented carbides

1995 ◽  
Vol 1 (2) ◽  
pp. 125-132 ◽  
Author(s):  
In-Chul Lee
Keyword(s):  
High Temperature ◽  
Plastic Flow ◽  
Threshold Stress ◽  
Cemented Carbides

scholarly journals Kinetic Analysis of High-Temperature Plastic Flow in 2.25Cr-1Mo-0.25V Steel

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4071
Author(s):  
Yongtao Zhang ◽  
Peng Luo ◽  
Longjiang Niu ◽  
Zhanpeng Lu ◽  
Haitao Yan ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Plastic Flow ◽  
Threshold Stress ◽  
Basic Mechanism ◽  
Band Model ◽  
True Activation Energy ◽  
Tension Tests ◽  
Kinetics Of ◽  
Modified Equation

High-temperature plastic flow of heat-resistant 2.25Cr-1Mo-0.25V steel was investigated by hot tension (at 500–650 °C) on a Gleeble 3800 machine. The strain rate of hot tension was set as 0.001–1 s−1. The constitutive relation of the steel was modeled by the introduction of the parameters termed “true activation energy” and “threshold stress”. Then, the kinetics of high-temperature plastic flow was analyzed based on an Arrhenius equation modified by a “threshold stress”. The stress exponent of the modified equation was equal to 5. True activation energy was estimated to be 132 kJ·mol−1. According to the slip band model, the basic mechanism behind the hot deformation of the steel was considered to be dislocation climbing, which was governed by grain boundary diffusion. This model proved to be successful in its analysis of the experimental results of hot tension tests.

scholarly journals High-Temperature Deformation of Naturally Aged 7010 Aluminum Alloy

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 581
Author(s):  
Abdulhakim A. Almajid
Keyword(s):  
Activation Energy ◽  
Aluminum Alloy ◽  
High Temperature ◽  
Threshold Stress ◽  
Activation Energies ◽  
Temperature Deformation ◽  
High Temperature Range ◽  
Temperature Range ◽  
True Activation Energy ◽  
Two Temperatures

This study is focused on the deformation mechanism and behavior of naturally aged 7010 aluminum alloy at elevated temperatures. The specimens were naturally aged for 60 days to reach a saturated hardness state. High-temperature tensile tests for the naturally aged sample were conducted at different temperatures of 573, 623, 673, and 723 K at various strain rates ranging from 5 × 10−5 to 10−2 s−1. The dependency of stress on the strain rate showed a stress exponent, n, of ~6.5 for the low two temperatures and ~4.5 for the high two temperatures. The apparent activation energies of 290 and 165 kJ/mol are observed at the low, and high-temperature range, respectively. These values of activation energies are greater than those of solute/solvent self-diffusion. The stress exponents, n, and activation energy observed are rather high and this indicates the presence of threshold stress. This behavior occurred as a result of the dislocation interaction with the second phase particles that are existed in the alloy at the testing temperatures. The threshold stress decreases in an exponential manner as temperature increases. The true activation energy was computed by incorporating the threshold stress in the power-law relation between the stress and the strain. The magnitude of the true activation energy, Qt dropped to 234 and 102 kJ/mol at the low and high-temperature range, respectively. These values are close to that of diffusion of Zinc in Aluminum and diffusion of Magnesium in Aluminum, respectively. The Zener–Hollomon parameter for the alloy was developed as a function of effective stress. The data in each region (low and high-temperature region) coalescence in a segment line in each region.

scholarly journals High-Temperature Creep Behavior of a Dispersion- and Solution-Hardened Al-3.1 at%Mg-1.3 vol%Be Alloy—Absence of Threshold Stress

1989 ◽  
Vol 53 (3) ◽  
pp. 296-302 ◽  
Author(s):  
Ying-Hwa Yeh ◽  
Masakazu Miyachi ◽  
Hideharu Nakashima ◽  
Hiroaki Kurishita ◽  
Shoji Goto ◽  
...  
Keyword(s):  
High Temperature ◽  
Creep Behavior ◽  
Threshold Stress ◽  
High Temperature Creep ◽  
Temperature Creep

Stress That Counteracts Electromigration: Threshold Versus Kinetic Approach

1994 ◽  
Vol 356 ◽  
Author(s):  
E. Glickman ◽  
N. Osipov ◽  
A. Ivanov
Keyword(s):  
Plastic Flow ◽  
Material Properties ◽  
Effective Viscosity ◽  
Threshold Stress ◽  
Stress Gradient ◽  
Material Constant ◽  
Induced Stress ◽  
Net Flux ◽  
Constant Yield ◽  
Coble Creep

AbstractThe paper analyzes electromigration (EM) conditions and material properties that determine the maximum EM induced stress, σa, and stress gradient, ∇σ, which counteract EM flow in interconnects.The first systematic data on the drift velocity vs. stripe length, L, current density, j, and temperature are presented for Al lines. In contrast to the conventional approach to the Blech problem with σa taken to be a material constant (“yield strength”), the observations suggest that σa increases with j. The stress adjustment is shown to result from the imperative coupling of the net flux of material directed to the downwind end of the stripe with the flux of plastic flow (creep) responsible for stress relaxation. The effect of parameters of the constitutive equation assumed to describe the plastic flow kinetics, namely that of strain rate exponent, threshold stress, and creep, effective viscosity, on the stress cya is considered. To account for the creep viscosity, η, obtained unpassivated aluminum stripes from EM experiments, a model for the attachment-controlled Coble creep is suggested.

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