Testing techniques to determine the deformation properties of concrete at elevated temperatures

1986 ◽  
Vol 19 (2) ◽  
pp. 105-110
Author(s):  
P. Schwesinger
Keyword(s):  
Elevated Temperatures ◽  
Deformation Properties ◽  
Testing Techniques

Fatigue Behavior of a 22Cr-20Ni-18Co-Fe Alloy at Elevated Temperatures

1994 ◽  
Vol 116 (1) ◽  
pp. 54-61 ◽  
Author(s):  
T. H. Krukemyer ◽  
A. Fatemi ◽  
R. W. Swindeman
Keyword(s):  
Experimental Investigation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Frequency Separation ◽  
Isothermal Fatigue ◽  
Deformation Properties ◽  
Fatigue Data ◽  
Haynes Alloy

An experimental investigation was conducted on Haynes Alloy 556 to study the fatigue behavior of the material at elevated temperatures. Fatigue tests were run at constant temperatures ranging from room temperature to 871°C with strain ranges from 0.265 to 1.5 percent resulting in lives between 102 and 106 cycles. Cyclic deformation properties were evaluated based on the fatigue data. Three fatigue life models were evaluated for their ability to predict the isothermal fatigue lives of the material. These included the Ostergren, Frequency Separation and Stress-Strain-Time models. Strengths and weaknesses of each model are discussed based on the experimental results.

Creep Assessment of Large Size High Temperature Components Using Small Creep Test Specimens

2016 ◽  
Author(s):  
Balhassn S. M. Ali
Keyword(s):  
High Temperature ◽  
Creep Test ◽  
Nuclear Power ◽  
Power Plants ◽  
Elevated Temperatures ◽  
Life Time ◽  
Safe Operation ◽  
Large Size ◽  
Testing Techniques ◽  
High Temperature Components

Most of the large components in the thermal, traditional and nuclear power plants such as pressurized vessels and pipes are operating at elevated temperatures. These temperatures and stress are high enough for creep to occur. For variety of reasons many of these power plants are now operating beyond their design life time. It is -known fact that as the high temperature components aged the failure rate normally increases as a result of their time dependent material damage. Further running of these components may become un-safe and dangerous in some cases. Therefore, creep assessment of the high temperature components of these plants is essential for their safe operation. Mainly for economic reasons these components have to be creep assessed as they are in service. However, assessing the creep strength for these high temperature components as they are in service, it can be challenging task, especially when these components are operating under extremely high temperature and/or stress. This paper introduces newly invented, small creep test specimens techniques. These new small types of specimens can be used to assess the remaining life times for the high temperature components, using only small material samples. These small material samples can be removed from the operating components surface, without affecting their safe operation. Two of the high temperature materials are used to validate the new testing techniques.

scholarly journals INFLUENCE OF INCREASED TEMPERATURE ON THE DYNAMIC PROPERTIES OF ASPEN

2021 ◽  
Vol 83 (1) ◽  
pp. 5-21
Author(s):  
A.M. Bragov ◽  
A.Yu. Konstantinov ◽  
A.K. Lomunov ◽  
T.N. Yuzhina
Keyword(s):  
Experimental Data ◽  
Elevated Temperatures ◽  
Dynamic Properties ◽  
Stress Strain ◽  
Horizontal Section ◽  
Mean Values ◽  
Damping Material ◽  
Deformation Properties ◽  
Relaxation Of Stresses ◽  
Strength And Deformation

As a damping material in the structures of containers for the transportation of hazardous materials, along with plastic metals, fiber-claydite concrete and synthetic foams, it is proposed to use wood of different species. Since containers are transported in different climate regimes, there is an urgent need to study the properties of wood at elevated temperatures. The paper presents the results of dynamic tests of aspen under uniaxial compression under conditions of temperature increased to +60°C. The tests were carried out according to the Kolsky method on a Hopkinson split-bar setup. To study the anisotropy of properties, aspen samples were made and tested by cutting samples along and across the direction of the grains. As a result of processing the experimental data, dynamic stress-strain curves were obtained. According to the experimental data, there are determined the stresses at which the integrity of the samples were violated. The mean values of the moduli of deformation in the active loading regions of stress-strain curves are also presented. The highest slope of the load sections and the highest breaking stresses were observed for the specimens when loaded along the grains, and the smallest values of these parameters were noted when loaded across the grains. For specimens loaded along grains at strain rates above 1500 s–1, after reaching the limiting stress values, a decrease (relaxation) of stresses is observed with increasing deformations. For specimens loaded across the grains, an almost horizontal section the diagrams of deforming or even with some strengthening is more typical. The effect of elevated temperature on the strength and deformation properties of aspen is estimated. There is a tendency towards some decrease in the diagrams at a temperature of +60 °C in comparison with the diagrams at room temperature. In this case, both the moduli in the loading and unloading sections and the limiting (breaking) stresses decrease. The obtained features of the behavior of aspen specimens at elevated temperatures should be taken into account when modeling deforming wood.

scholarly journals Properties of Concrete at Elevated Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Venkatesh Kodur
Keyword(s):  
Fire Resistance ◽  
Elevated Temperatures ◽  
Mechanical Deformation ◽  
Structural Members ◽  
Fire Response ◽  
Key Characteristics ◽  
Deformation Properties ◽  
Different Types ◽  
Resistance Performance

Fire response of concrete structural members is dependent on the thermal, mechanical, and deformation properties of concrete. These properties vary significantly with temperature and also depend on the composition and characteristics of concrete batch mix as well as heating rate and other environmental conditions. In this chapter, the key characteristics of concrete are outlined. The various properties that influence fire resistance performance, together with the role of these properties on fire resistance, are discussed. The variation of thermal, mechanical, deformation, and spalling properties with temperature for different types of concrete are presented.

scholarly journals Thermal and mechanical properties of steel-fibre-reinforced concrete at elevated temperatures

1996 ◽  
Vol 23 (2) ◽  
pp. 511-517 ◽  
Author(s):  
T. T. Lie ◽  
V. K. R. Kodur
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Reinforced Concrete ◽  
Fire Resistance ◽  
Elevated Temperatures ◽  
Steel Fibre ◽  
Fibre Reinforced Concrete ◽  
Thermal And Mechanical Properties ◽  
Steel Fibre Reinforced Concrete ◽  
Deformation Properties

For use in fire resistance calculations, the relevant thermal and mechanical properties of steel-fibre-reinforced concrete at elevated temperatures were determined. These properties included the thermal conductivity, specific heat, thermal expansion, and mass loss, as well as the strength and deformation properties of steel-fibre-reinforced siliceous and carbonate aggregate concretes. The thermal properties are presented in equations that express the values of these properties as a function of temperature in the temperature range between 0 °C and 1000 °C. The mechanical properties are given in the form of stress–strain relationships for the concretes at elevated temperatures. The results indicate that the steel fibres have little influence on the thermal properties of the concretes. The influence on the mechanical properties, however, is relatively greater than the influence on the thermal properties and is expected to be beneficial to the fire resistance of structural elements constructed of fibre-reinforced concrete. Key words: steel fibre, reinforced concrete, thermal properties, mechanical properties, fire resistance.

Creep-Environment Interactions of Alloy 617 at Elevated Temperature

2008 ◽  
Author(s):  
Daejong Kim ◽  
Changheui Jang ◽  
Woo Seog Ryu
Keyword(s):  
High Temperature ◽  
Creep Strain ◽  
Elevated Temperatures ◽  
Extended Period ◽  
Nickel Base Superalloy ◽  
Environment Interaction ◽  
Creep Tests ◽  
Alloy 617 ◽  
Creep Properties ◽  
Deformation Properties

Creep behavior and degradation of creep properties of high-temperature materials often limit the lives of components and structures designed to operate for extended period under stress at elevated temperatures. A nickel-base superalloy, Alloy 617 in particular which is considered as a prospective material for hot gas duct and intermediate heat exchanger in very high temperature gas cooled reactor, was studied for creep properties. Creep tests were carried out under various sustained tensile loadings in air and helium environments at temperature of 800°C, 900°C, and 1000°C. Times for 1% creep strain and creep rupture were taken from the short-term creep tests within 1000 hours. Effect of creep-environment interaction on creep strain and changes in viscous deformation properties by dynamic recrystallization were discussed.

Mechanical properties of a 20 vol % SiC whisker-reinforced, yttria-stabilized, tetragonal zirconia composite at elevated temperatures

1995 ◽  
Vol 10 (1) ◽  
pp. 113-118 ◽  
Author(s):  
S.E. Dougherty ◽  
T.G. Nieh ◽  
J. Wadsworth ◽  
Y. Akimune
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Tetragonal Zirconia ◽  
Tensile Tests ◽  
Engineering Properties ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Deformation Properties ◽  
Before And After

The high-temperature deformation behavior of a SiC whisker-reinforced, yttria-stabilized, tetragonal zirconia polycrystalline composite containing 20 vol % SiC whiskers (SiC/Y-TZP) has been investigated. Tensile tests were performed in vacuum at temperatures from 1450 °C to 1650 °C and at strain rates from 10−3 to 10−5 s−1. The material exhibits useful high-temperature engineering properties (e.g., ∼100 MPa and 16% elongation at T = 1550 °C and at a strain rate of ∼10−4 s−1). The stress exponent was determined to be n ≍ 2. Scanning electron microscopy was used to characterize the grain size and morphology of the composites, both before and after deformation. The grain size in the composite was initially fine, but coarsened at the test temperatures; both dynamic and static grain growth were observed. The morphology of ceramic reinforcements appears to affect strongly the plastic deformation properties of Y-TZP. A comparison is made between the properties of monolithic Y-TZP, 20 wt. % Al2O3 particulate-reinforced Y-TZP (Al2O3/Y-TZP), and SiC/Y-TZP composites.

Hardness and deformation properties of solids at very high temperatures

1966 ◽  
Vol 292 (1431) ◽  
pp. 441-459 ◽  
Keyword(s):  
Elevated Temperatures ◽  
Sintered Material ◽  
Strength Properties ◽  
Indentation Hardness ◽  
Intrinsic Properties ◽  
Empirical Relations ◽  
Rapid Fall ◽  
Deformation Properties ◽  
Semi Empirical ◽  
Very High

This paper describes an experimental study of the deformation and strength properties of refractory solids at temperatures up to 2000 °C. It is difficult to make direct stress-strain measurements at elevated temperatures on small specimens of these materials, and consequently the strength property measured was in dentation hardness. The problem of obtaining an indenter that is sufficiently hard and stable at these temperatures was overcome by indenting a cylinder or prism of the material with an identical specimen of the same material. Mutual indentation measurements obtained in this way show that at low temperatures most of the refractory solids are very hard but brittle. Above a critical temperature they become ductile and the hardness falls as the temperature increases. With sintered porous specimens the fall in hardness is augmented by collapse of the structure and compaction of the material. At higher temperatures the behaviour is dominated by the intrinsic properties of the solid and the hardness properties of the sintered material resemble those of fully compacted crystalline specimens. For most of the refractory solids, as for pure metals, the most rapid fall in hardness occurs at temperatures above about one-half of the absolute melting point, T m . By contrast the carbides of titanium and tungsten fall off rapidly in hardness at temperatures between 0.2 and 0.4 T m , probably on account of the increased mobility of the carbon atoms. At any one temperature the indentation hardness decreases as the loading time is increased. Semi-empirical relations may be used to describe this and it is possible to deduce an activation energy for the creep processes involved. The results show that the only materials having an indentation hardness above 100 Kg/mm 2 at 1500 °C are the nitrides and carbides of silicon.

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