Accuracy of High-Temperature, Constant Rate of Strain Flow Curves

2008 ◽  
pp. 206-206-11 ◽  
Author(s):  
JG Lenard ◽  
AN Karagiozis
Keyword(s):  
High Temperature ◽  
Flow Curves ◽  
Constant Rate ◽  
Temperature Constant

Characteristics and aging of SiC MOSFETs operated at very high temperatures

2014 ◽  
Vol 1693 ◽  
Author(s):  
Dean P. Hamilton ◽  
Michael R. Jennings ◽  
Craig A. Fisher ◽  
Yogesh K. Sharma ◽  
Stephen J. York ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Threshold Voltage ◽  
Thermal Aging ◽  
Ohmic Contacts ◽  
Stress Tests ◽  
Temperature Capability ◽  
Temperature Constant ◽  
Voltage Management ◽  
Very High

ABSTRACTSilicon carbide power devices are purported to be capable of operating at very high temperatures. Current commercially available SiC MOSFETs from a number of manufacturers have been evaluated to understand and quantify the aging processes and temperature dependencies that occur when operated up to 350°C. High temperature constant positive bias stress tests demonstrated a two times increase in threshold voltage from the original value for some device types, which was maintained indefinitely but could be corrected with a long negative gate bias. The threshold voltages were found to decrease close to zero and the on-state resistances increased quite linearly to approximately five or six times their room temperature values. Long term thermal aging of the dies appears to demonstrate possible degradation of the ohmic contacts. This appears as a rectifying response in the I-V curves at low drain-source bias. The high temperature capability of the latest generations of these devices has been proven independently; provided that threshold voltage management is implemented, the devices are capable of being operated and are free from the effects of thermal aging for at least 70 hours cumulative at 300°C.

High-temperature Deformation Kinetics of Gold at 473K to 773K

2008 ◽  
Vol 1137 ◽  
Author(s):  
Vineet Bhakhri ◽  
Robert J. Klassen
Keyword(s):  
High Temperature ◽  
Cell Structure ◽  
Dislocation Cell ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Indentation Creep ◽  
Creep Tests ◽  
Dislocation Glide ◽  
Deformation Kinetics ◽  
Temperature Constant

AbstractHigh-temperature constant-force indentation creep tests of 200 seconds duration were performed on an annealed gold specimen at 473K to 773K, to investigate the dependence of the micro-/nano-indentation deformation kinetics upon indentation stress, temperature and time. The indent stress displayed a clear indentation size effect at 473 K. An analysis of the measured indentation creep rate, and its dependence upon temperature and stress, indicate that the strength of the deformation rate limiting obstacles increases with temperature. This is consistent with the expected temperature dependent evolution of the dislocation cell structure whose boundaries become the primary obstacles to dislocation glide.

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.

CARPENTER LOW EXPANSION 45

Alloy Digest ◽  
2004 ◽  
Vol 53 (12) ◽  
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Iron Alloy ◽  
Heat Treating ◽  
Nickel Iron ◽  
Temperature Performance ◽  
Constant Rate ◽  
Nickel Iron Alloy

Abstract Carpenter Low-Expansion 45 alloy is a 45% nickel-iron alloy with a constant rate of thermal expansion useful in thermostats. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as heat treating and joining. Filing Code: FE-134. Producer or source: Carpenter.

Low temperature constant rate thermodesorption as a tool to characterise porous solids

2000 ◽  
Vol 360 (1) ◽  
pp. 77-83 ◽  
Author(s):  
V Chevrot ◽  
P.L Llewellyn ◽  
F Rouquerol ◽  
J Godlewski ◽  
J Rouquerol
Keyword(s):  
Low Temperature ◽  
Porous Solids ◽  
Constant Rate ◽  
Temperature Constant

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.

Manufacturing Technique and Stab-Resistance Evaluation of Three-Dimensional Nylon 6/LPET Compound Nonwoven Fabrics

2014 ◽  
Vol 910 ◽  
pp. 170-173 ◽  
Author(s):  
Ching Wen Lou ◽  
Po Ching Lu ◽  
Hsuan Mao Yeh ◽  
Jia Horng Lin
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Impact Strength ◽  
Three Dimensional ◽  
Polyamide 6 ◽  
Nylon 6 ◽  
Puncture Resistance ◽  
Nonwoven Fabrics ◽  
Constant Rate ◽  
Stab Resistance

This study aims to examine the influence of the temperatures of heat treatment on the puncture-resistance of Nylon6/LPET compound nonwoven fabrics. Polyamide 6 (Nylon 6) fibers and low-melting-point polyester (LPET) fibers are combined and undergo a heat treatment to make three-dimensional (3-D) Nylon 6/LPET compound nonwoven fabrics through a nonwoven process. The nonwoven fabrics are tested for their dynamic puncture resistance, constant rate puncture resistance, and impact strength. The experiment results show that when thermally treated at a high temperature, the compound nonwoven fabrics are rendered with a lower dynamic puncture resistance and a lower constant rate puncture resistance, but a greater impact strength.

Characterization of Dynamic Globularization Behavior during Hot Working of Ti-6Al-4V Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 1033-1036 ◽  
Author(s):  
Jong Taek Yeom ◽  
Jeoung Han Kim ◽  
Nam Yong Kim ◽  
Nho Kwang Park ◽  
Chong Soo Lee
Keyword(s):  
High Temperature ◽  
Microstructure Evolution ◽  
True Strain ◽  
Hot Working ◽  
Strain Rates ◽  
Flow Curves ◽  
Deformation Parameters ◽  
Wide Range ◽  
Lamellae Structure

The dynamic globularization behavior during hot working of Ti-6Al-4V alloy was investigated by high temperature torsion tests. The torsion tests were carried out to investigate microstructure evolution occurring during dynamic globularization in Ti-6Al-4V alloy. The torsion tests were performed under a wide range of temperatures and strain rates with true strain up to 2. The flow curves revealed that the amount of flow softening for the fine alpha-lamellae structure was higher than that for the coarse alpha-lamellae structure under the temperature of 900oC. The effects of hot deformation parameters and initial microstructures on the dynamic globularization were analyzed.

Evidence of Hot-Electron Degradation in GaN-Based MIS-HEMTs Submitted to High Temperature Constant Source Current Stress

2016 ◽  
Vol 37 (11) ◽  
pp. 1415-1417 ◽  
Author(s):  
Maria Ruzzarin ◽  
Matteo Meneghini ◽  
Isabella Rossetto ◽  
Marleen Van Hove ◽  
Steve Stoffels ◽  
...  
Keyword(s):  
High Temperature ◽  
Hot Electron ◽  
Current Stress ◽  
Source Current ◽  
Temperature Constant ◽  
Constant Source
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