Rheological modelling of high‐temperature stationary creep tests of Grade S275JR steel

ce/papers ◽  
2021 ◽  
Vol 4 (2-4) ◽  
pp. 546-550
Author(s):  
Neno Torić ◽  
Ian Burgess
Keyword(s):  
High Temperature ◽  
Creep Tests ◽  
Rheological Modelling ◽  
Stationary Creep

Creep Properties and Interfacial Microstructure of SiC Whisker Reinforced Si3N4

1989 ◽  
Vol 170 ◽  
Author(s):  
Håkan A. Swan ◽  
Colette O'meara
Keyword(s):  
High Temperature ◽  
Creep Resistance ◽  
Interfacial Microstructure ◽  
Deformation Mechanisms ◽  
Amorphous Films ◽  
Creep Tests ◽  
Creep Properties ◽  
High Temperature Exposure ◽  
Temperature Exposure

AbstractPreliminary creep tests were performed on SiC whisker reinforced and matrix Si3N4 material fabricated by the NPS technique. The material was extensively crystallised in the as received material, leaving only thin amorphous films surrounding the grains. No improvement in the creep resistance could be detected for the whisker reinforced material. The deformation mechanisms were found to be that of cavitation in the form of microcracks, predominantly at the whisker/matrix interfaces, and the formation of larger cracks. Extensive oxidation of the samples, as a result of high temperature exposure to air, was observed for the materials tested at 1375°C.

scholarly journals Creep damage behavior of red sandstone after high temperature

2021 ◽  
Author(s):  
Xiaokang Pan ◽  
Filippo Berto ◽  
Xiaoping Zhou
Keyword(s):  
High Temperature ◽  
Uniaxial Compression ◽  
Deformation Modulus ◽  
Creep Damage ◽  
Viscosity Coefficient ◽  
Creep Tests ◽  
Red Sandstone ◽  
Instantaneous Strain ◽  
Treated Sample ◽  
Instantaneous Deformation

This work discusses the results from tests conducted to investigate the uniaxial compression and creep behavior of red sandstone. The original untreated sample and the 800 ℃ treated sample have been selected to carry out the experiments. It has been found that high temperature has obvious influence on the mechanical properties of red sandstone. The relationship between creep strain and instantaneous strain, as well as instantaneous deformation modulus and creep viscosity coefficient have been analyzed. It has been found that high temperature reduces the ability of red sandstone to resist instantaneous deformation and creep deformation. Acoustic emission (AE) technology has been also used in the loading process of uniaxial compression and creep tests, providing a powerful means for damage evolution analysis of red sandstone.

Analysis on Fracture Morphology and Microstructure of T92 Steel after High Temperature Multiaxial Creep

2013 ◽  
Vol 860-863 ◽  
pp. 967-971
Author(s):  
Xue Ping Mao ◽  
Xiao Wang ◽  
Sai Dong Huang ◽  
Chao Li ◽  
Hong Xu ◽  
...  
Keyword(s):  
High Temperature ◽  
Stress State ◽  
Standard Specimen ◽  
Uniaxial Stress ◽  
Fracture Morphology ◽  
Multiaxial Stress ◽  
Creep Life ◽  
Creep Tests ◽  
Multiaxial Stress State ◽  
Multiaxial Creep

The high temperature creep tests of standard specimen and double U-type notch specimen of T92 steel were carried out under different stresses at 650 °C. Then optical microscopy and scanning electron microscopy were used to observe the fracture morphology and microstructure. The results show that the multiaxial stress state leads to the creep fracture cracking initiation in notch. Under multiaxial stress state, the failure mode of T92 steel is transgranular and dimple plastic fracture, and is more obvious with the increase of creep life. Compared with under uniaxial stress state, the precipitates under multiaxial stress state are larger in size and quantity, and are much coarser.

Factors Affecting Choice of Working Stresses for High-Temperature Service

1933 ◽  
Vol 1 (3) ◽  
pp. 99-102
Author(s):  
P. G. McVetty
Keyword(s):  
High Temperature ◽  
Published Data ◽  
Creep Tests ◽  
Fundamental Study ◽  
Factors Affecting ◽  
Creep Characteristics ◽  
The Stability ◽  
Safe Working

Abstract This paper discusses the various methods which have been proposed to determine safe working stresses for high-temperature service. The question of the stability of alloys during the test and in subsequent service is considered, with particular emphasis upon probable changes in creep characteristics during long exposure to stress and temperature. It is shown that published data in general do not admit of extrapolation, and that attempts to estimate total creep in service from such data are not usually satisfactory. The author stresses the need for more fundamental study of the laws governing creep rather than creep tests of many different materials.

Understanding the Effects of Processing on the Mechanical Behavior of a SI3N4 Ceramic Through Microstructural Investigations

2001 ◽  
Author(s):  
Q. Wei ◽  
J. Sankar
Keyword(s):  
High Temperature ◽  
Mechanical Behavior ◽  
Triple Junctions ◽  
Sintering Aids ◽  
Si3n4 Ceramic ◽  
Creep Tests ◽  
Furnace Annealing ◽  
Conventional Furnace ◽  
Different Temperatures ◽  
Si3n4 Ceramics

Abstract The mechanical properties of silicon nitride (Si3N4) ceramics are determined by their microstructure, which in turn depends on processing routes adopted to fabricate the material. To obtain dense Si3N4, sintering aids are almost always added during the densification process. The sintering aids remain in the ceramics as amorphous residues which adversely affect the high temperature mechanical behavior of the material. In this paper, we have investigated the effects of processing on the mechanical behavior of a sintered Si3N4 ceramic through detailed microstructural observations. A commercial Si3N4 was annealed using conventional furnace annealing and microwave annealing at different temperatures. Creep tests were performed to compare the high temperature mechanical behavior of the as-sintered and annealed ceramics. It was found that microwave and furnace annealing heat-treatments improve the creep resistance of the ceramic through devitrification of the triple junctions phases.

Cantilever creep method for testing ceramic composites and a case study for chemically bonded phosphate ceramic composites reinforced with glass, carbon and basalt fibers, including both experiments and simulations

2020 ◽  
Vol 54 (20) ◽  
pp. 2663-2676
Author(s):  
Henry A Colorado ◽  
Elkin I Gutiérrez-Velásquez ◽  
Clem Hiel
Keyword(s):  
High Temperature ◽  
Large Scale ◽  
Extreme Environments ◽  
Ceramic Composites ◽  
High Temperature Creep ◽  
Creep Tests ◽  
Element Analysis ◽  
Temperature Creep ◽  
Glass Carbon ◽  
Electron Microscopy Analysis

This paper presented the cantilever beam experiments and the method for creep in chemically bonded ceramics reinforced with glass, carbon, and basalt unidirectional fibers. The ceramic composite samples were fabricated by mixing wollastonite powder and phosphoric acid, through the resonant acoustic mixing technique. The reinforced fibers were added via pultrusion process. The manufactured materials were exposed to high temperature creep tests at 600, 800 and 1000℃, with an annealing time of 1 h, all in air environment. Some examples of real large-scale structures made manually by a company were also included. In order to understand the microstructure, X-ray diffraction and scanning electron microscopy analysis were included. The presented method is simple and can be used in any inorganic ceramic slurry types, such as geopolymers, phosphate cements, clay-based materials, or Portland cement composites. The sample response in high temperature creep experiments was analyzed with a new but very simple technique, and modeled using finite element analysis over all compositions. Results revealed that fibers have a significant effect on the composite creep when compared to the ceramic without reinforcement, and particularly carbon fibers showed a quite interested effect in reducing the creep effects. Results show the limit of the materials under conditions typically found in fires and other extreme environments.

Creep Property of Boron Added 9Cr Heat Resistant Steels after Welding

2018 ◽  
Vol 941 ◽  
pp. 340-345
Author(s):  
Tetsuya Matsunaga ◽  
Maaouia Souissi ◽  
Ryoji Sahara ◽  
Hiromichi Hongo ◽  
Masaaki Tabuchi ◽  
...  
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Rapid Heating ◽  
Boundary Migration ◽  
Creep Property ◽  
Creep Tests ◽  
Precipitate Morphology ◽  
Premature Failure ◽  
Heat Resistant ◽  
Type Iv

Although welding results in premature failure by type IV fracture under high temperature creep conditions, the alloy design of light elements such as boron addition and nitrogen reduction enhances the creep lifetime of 9Cr heat resistant steel. In particular, the simulated heat affected zone (SHAZ) sample of new 9Cr steel (called TA steel) shows about 10 times longer creep lifetime than that of the standard Gr. 91 steel. The welded TA steel is thus expected to exhibit good creep properties because its SHAZ sample has coarser grains and suppresses type IV fracture. The preservation of base metal’s microstructure after welding results from the precipitate morphology, such as high grain boundary coverage by precipitates and low amount of MX being nucleation sites of ferrite grains during the a-g phase transformation. In addition, the increase of stability of M23C6 affects high pinning pressure toward grain boundary migration upon rapid heating during welding. First-principles calculations confirm the increased stability when boron is absorbed by M23C6. Moreover, the calculations reveals that boron decreases the coherency between matrix and M23C6, suppressing grain coarsening during creep tests in TA steel. It is concluded that the increased microstructural stability during welding and long high temperature exposure generates the elongated creep lifetime in welded TA steel including about 0.01 wt% boron and less than 0.01 wt% nitrogen.

scholarly journals A Constitutive Model for the Mechanical Behavior of Single Crystal Silicon at Elevated Temperature

2001 ◽  
Vol 687 ◽  
Author(s):  
H.-S. Moon ◽  
L. Anand ◽  
S. M. Spearing
Keyword(s):  
High Temperature ◽  
Constitutive Model ◽  
Single Crystal ◽  
Mechanical Behavior ◽  
Elevated Temperatures ◽  
Single Crystal Silicon ◽  
Operational Environment ◽  
Localized Deformation ◽  
Creep Tests ◽  
Crystal Silicon

AbstractSilicon in single crystal form has been the material of choice for the first demonstration of the MIT microengine project. However, because it has a relatively low melting temperature, silicon is not an ideal material for the intended operational environment of high temperature and stress. In addition, preliminary work indicates that single crystal silicon has a tendency to undergo localized deformation by slip band formation. Thus it is critical to obtain a better understanding of the mechanical behavior of this material at elevated temperatures in order to properly exploit its capabilities as a structural material. Creep tests in simple compression with n-type single crystal silicon, with low initial dislocation density, were conducted over a temperature range of 900 K to 1200 K and a stress range of 10 MPa to 120 MPa. The compression specimens were machined such that the multi-slip <100> or <111> orientations were coincident with the compression axis. The creep tests reveal that response can be delineated into two broad regimes: (a) in the first regime rapid dislocation multiplication is responsible for accelerating creep rates, and (b) in the second regime an increasing resistance to dislocation motion is responsible for the decelerating creep rates, as is typically observed for creep in metals. An isotropic elasto-viscoplastic constitutive model that accounts for these two mechanisms has been developed in support of the design of the high temperature turbine structure of the MIT microengine.

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.

Rheological modelling of masonry creepThis article is one of a selection of papers published in this Special Issue on Masonry.

2007 ◽  
Vol 34 (11) ◽  
pp. 1506-1517 ◽  
Author(s):  
Kyoung-Kyu Choi ◽  
Shelley L. Lissel ◽  
Mahmoud M. Reda Taha
Keyword(s):  
Stress Level ◽  
Rheological Model ◽  
Creep Behaviour ◽  
Model Development ◽  
Sustained Load ◽  
Creep Tests ◽  
Standard Type ◽  
Rheological Models ◽  
Proposed Model ◽  
Rheological Modelling

In the present study, masonry creep was experimentally investigated. Creep tests were performed on masonry prisms, which were produced using standard fired clay brick and standard Type S mortar. A total of 11 sets of loaded and unloaded masonry specimens were tested under sustained load with three main parameters: stress level, masonry age at loading, and relative humidity. The unloaded prisms compensated for the effects of shrinkage. In this article, the ability of a number of rheological models reported in the literature are examined for their ability to predict masonry creep. Moreover, a new rheological model, one that considers the effect of stress level and masonry age at loading, is proposed. The system parameters of the proposed model were identified using the experimental data. The proposed model was then validated using masonry creep data that was reported by other researchers, but not used in model development. It is shown that the creep behaviour of masonry can be modelled with good accuracy using the proposed rheological model.

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