Kinetics of decomposition of supercooled austenite and the mechanical properties of the SP70D3 steel before and after impregnating with copper

1992 ◽  
Vol 31 (9) ◽  
pp. 777-781
Author(s):  
Yu. G. Gurevich ◽  
A. G. Ivashko ◽  
V. I. Rakhmanov ◽  
I. F. Pan'shin
Keyword(s):  
Mechanical Properties ◽  
Supercooled Austenite ◽  
Kinetics Of Decomposition ◽  
Before And After ◽  
Kinetics Of

Kinetics of decomposition of the supercooled austenite of 32G2 steel during continuous and interrupted accelerated quenching

1985 ◽  
Vol 27 (3) ◽  
pp. 174-177
Author(s):  
Yu. P. Gul' ◽  
V. S. Chmeleva ◽  
M. F. Evsyukov ◽  
Yu. V. Yakubovich ◽  
V. K. Chernykh
Keyword(s):  
Supercooled Austenite ◽  
Kinetics Of Decomposition ◽  
Kinetics Of

Effect of High Temperature Exposure on the Mechanical Properties and Moisture Absorption Kinetics of Graphite/Epoxy Laminates

2006 ◽  
Author(s):  
Levent Aktas ◽  
Nam Hoang Vu ◽  
M. Cengiz Altan
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Elevated Temperatures ◽  
Moisture Absorption ◽  
Slight Reduction ◽  
Absorption Kinetics ◽  
Maximum Increase ◽  
Before And After ◽  
Temperature Exposure ◽  
Kinetics Of

This study investigates the effect of exposure to elevated temperatures on the mechanical properties and moisture absorption kinetics of a graphite/epoxy composite laminate. 16-ply unidirectional AS4/3501-6 laminates are cured in an autoclave. The temperature profile during cure cycle involves a ramp of 5°C/min followed by a 3-hour hold at 177°C (350°F). The test samples obtained from these laminates are subjected to 150, 200, 250, 275, 300 and 325°C for 30min. Flexural strength and stiffness of the samples are characterized by three-point bending tests before and after the temperature exposure. These samples are then immersed into distilled water at 80°C and weighed at regular intervals to characterize their moisture absorption kinetics. Stiffness remained nearly unaffected from exposure to elevated temperatures except for 300 and 325°C. At 300 and 325°C, up to 21% and 58% reductions in flexural stiffness with respect to the control samples is observed, respectively. On the other hand, flexural strength displayed slight reduction at 250°C and resulted in over 60% and 88% deterioration for 300 and 325°C, respectively. Exposure to 150 and 200°C did not result in significant changes in mechanical properties. However, moisture absorption experiments indicated an increase in the rate of diffusion even if the mechanical properties are unaffected. The diffusion coefficient displayed an increase of 27% for 150°C, 75% for 200°C, reaching a maximum increase of 600% for 300°C exposure.

scholarly journals Investigation of the decay kinetics of austenite with continuous cooling K76F steel for wide-gauge railway rails

2018 ◽  
pp. 317-327
Author(s):  
A.I. Babachenko ◽  
A.A. Kononenko ◽  
A.M. Khulin
Keyword(s):  
Heat Treatment ◽  
High Strength ◽  
Operational Reliability ◽  
Supercooled Austenite ◽  
Decay Kinetics ◽  
Iron And Steel ◽  
Continuous Cooling ◽  
Kinetics Of Decomposition ◽  
Dilatometric Studies ◽  
Kinetics Of

The aim of the work is to study the kinetics of decomposition of supercooled austenite with continuous cooling of steel for railway rails with a high content of manganese and micro-alloyed vanadium. The relevance of the work is the need to determine the possibility of producing rails from K76 F steel according to foreign standards, in particular EN 13674-1-2011. During the research, a thermo-kinetic diagram was constructed with different cooling rates for samples of K76F steel heated by the heating mode for quenching the rails in an induction unit at the heat treatment site at Azovstal Iron and Steel Works. Dilatometric studies have shown that when samples are heated at a rate of 300С/min in steel for railway rails, polymorphic  -transformation begins at temperature 7350С (Ас1), ends at 7600С (Ас3). It is established that the temperatures of the beginning and completion of the formation of ferrite, perlite and bainite decrease with increasing cooling rate. With an increase in the rate of cooling, the morphology changes and the dispersion of perlite increases - from the middle plate of frequent perlite to highly dispersed sorbitol structures and quenching troostite. It was concluded that in the studied steel grade K76F with 0.80%С, 0.25%Si, 0.97%Mn, 0.055%V, it is impossible to achieve hardness above 400НВ without the formation of bainite. For the manufacture of high-strength rails of category R400HT EN 13674-1-2011, it is necessary to create steel of a new chemical composition. It is shown that it is possible to develop grounded reinforcing heat treatment mode and to increase the operational reliability of rails by defining critical points and studying the kinetics of decomposition of supercooled austenite with continuous cooling of steel.

scholarly journals Mathematical Modelling of Kinetics of Decomposition of the Supercooled Austenite in Alloyed Steels

2017 ◽  
Vol 39 (8) ◽  
pp. 1051-1068 ◽  
Author(s):  
V. V. Kaverynsky ◽  
◽  
A. I. Trotsan ◽  
Z. P. Sukhenko ◽  
◽  
...  
Keyword(s):  
Mathematical Modelling ◽  
Supercooled Austenite ◽  
Kinetics Of Decomposition ◽  
Kinetics Of

Sunlight exposure: the effects on the performance of paragliding fabric

2018 ◽  
Vol 69 (05) ◽  
pp. 381-389
Author(s):  
MENGÜÇ GAMZE SÜPÜREN ◽  
TEMEL EMRAH ◽  
BOZDOĞAN FARUK
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Air Permeability ◽  
Sunlight Exposure ◽  
Test Results ◽  
Coating Materials ◽  
Strength Tests ◽  
Before And After ◽  
The Relationship ◽  
Dark Blue

This study was designed to explore the relationship between sunlight exposure and the mechanical properties of paragliding fabrics which have different colors, densities, yarn counts, and coating materials. This study exposed 5 different colors of paragliding fabrics (red, turquoise, dark blue, orange, and white) to intense sunlight for 150 hours during the summer from 9:00 a.m. to 3:00 p.m. for 5 days a week for 5 weeks. Before and after the UV radiation aging process, the air permeability, tensile strength, tear strength, and bursting strength tests were performed. Test results were also evaluated using statistical methods. According to the results, the fading of the turquoise fabric was found to be the highest among the studied fabrics. It was determined that there is a significant decrease in the mechanical properties of the fabrics after sunlight exposure. After aging, the fabrics become considerably weaker in the case of mechanical properties due to the degradation in both the dyestuff and macromolecular structure of the fiber

Kinetics and Mechanism of Decomposition of 1,3-Bis(4-methylphenyl)triazene Catalyzed with Substituted Benzoic Acids in 25% Aqueous Methanol-General or Specific Catalysis?

1994 ◽  
Vol 59 (9) ◽  
pp. 2029-2041
Author(s):  
Oldřich Pytela ◽  
Taťjana Nevěčná
Keyword(s):  
Benzoic Acids ◽  
Hammett Equation ◽  
Aqueous Methanol ◽  
Mechanism Of Decomposition ◽  
Kinetics Of Decomposition ◽  
Independent Variable ◽  
Amino Derivatives ◽  
Substituted Benzoic Acids ◽  
The Individual ◽  
Kinetics Of

The kinetics of decomposition of 1,3-bis(4-methylphenyl)triazene catalyzed with 13 substituted benzoic acids of various concentrations have been measured in 25 vol.% aqueous methanol at 25.0 °C. The rate constants observed (297 data) have be used as values of independent variable in a series of models of the catalyzed decomposition. For the catalytic particles were considered the undissociated acid, its conjugated base, and the proton in both the specific and general catalyses. Some models presumed formation of reactive or nonreactive complexes of the individual reactants. The substituent effect is described by the Hammett equation. The statistically best model in which the observed rate constant is a superposition of a term describing the dependence on proton concentration and a term describing the dependence on the product of concentrations of proton and conjugated base is valid with the presumption of complete proton transfer from the catalyst acid to substrate, which has been proved. The behaviour of 4-dimethylamino, 4-amino, and 3-amino derivatives is anomalous (lower catalytic activity as compared with benzoic acid). This supports the presumed participation of conjugated base in the title process.

Elaboration and Characterization of the Properties of Refractory Cr Base Alloys

2010 ◽  
Vol 72 ◽  
pp. 46-52 ◽  
Author(s):  
Laurent Royer ◽  
Stéphane Mathieu ◽  
Christophe Liebaut ◽  
Pierre Steinmetz
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Molten Glass ◽  
Energy Production ◽  
Creep Properties ◽  
Refractory Alloys ◽  
Industrial Use ◽  
Kinetics Of ◽  
Selection Of

For energy production and also for the glass industry, finding new refractory alloys which could permit to increase the process temperatures to 1200°C or more is a permanent challenge. Chromium base alloys can be good candidates, considering the melting point of Cr itself, and also its low corrosion rate in molten glass. Two families of alloys have been studied for this purpose, Cr-Mo-W and Cr-Ta-X alloys (X= Mo, Si..). A finer selection of compositions has been done, to optimize their chemical and mechanical properties. Kinetics of HT oxidation by air, of corrosion by molten glass and also creep properties of several alloys have been measured up to 1250°C. The results obtained with the best alloys (Cr-Ta base) give positive indications as regards the possibility of their industrial use.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

scholarly journals Effects of equal channel angular pressing and heat treatments on the microstructures and mechanical properties of selective laser melted and cast AlSi10Mg alloys

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Przemysław Snopiński ◽  
Mariusz Król ◽  
Marek Pagáč ◽  
Jana Petrů ◽  
Jiří Hajnyš ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Equal Channel Angular Pressing ◽  
Heat Treatments ◽  
Electron Backscattered Diffraction ◽  
Angular Pressing ◽  
Low Temperature Annealing ◽  
Transmission Electron ◽  
Before And After ◽  
The Impact

AbstractThis study investigated the impact of the equal channel angular pressing (ECAP) combined with heat treatments on the microstructure and mechanical properties of AlSi10Mg alloys fabricated via selective laser melting (SLM) and gravity casting. Special attention was directed towards determining the effect of post-fabrication heat treatments on the microstructural evolution of AlSi10Mg alloy fabricated using two different routes. Three initial alloy conditions were considered prior to ECAP deformation: (1) as-cast in solution treated (T4) condition, (2) SLM in T4 condition, (3) SLM subjected to low-temperature annealing. Light microscopy, transmission electron microscopy, X-ray diffraction line broadening analysis, and electron backscattered diffraction analysis were used to characterize the microstructures before and after ECAP. The results indicated that SLM followed by low-temperature annealing led to superior mechanical properties, relative to the two other conditions. Microscopic analyses revealed that the partial-cellular structure contributed to strong work hardening. This behavior enhanced the material’s strength because of the enhanced accumulation of geometrically necessary dislocations during ECAP deformation.

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