ASTM E2714-09e1
(Test Method)Standard Test Method for Creep-Fatigue Testing
Standard Test Method for Creep-Fatigue Testing
SIGNIFICANCE AND USE
Creep-fatigue testing is typically performed at elevated temperatures and involves the sequential or simultaneous application of the loading conditions necessary to generate cyclic deformation/damage enhanced by creep deformation/damage or vice versa. Unless such tests are performed in vacuum or an inert environment, oxidation can also be responsible for important interaction effects relating to damage accumulation. The purpose of creep-fatigue tests can be to determine material property data for (a) assessment input data for the deformation and damage condition analysis of engineering structures operating at elevated temperatures (b) the verification of constitutive deformation and damage model effectiveness (c) material characterization, or (d) development and verification of rules for new construction and life assessment of high-temperature components subject to cyclic service with low frequencies or with periods of steady operation, or both.
In every case, it is advisable to have complementary continuous cycling fatigue data (gathered at the same strain/loading rate) and creep data determined from test conducted as per Practice E139 for the same material and test temperature(s). The procedure is primarily concerned with the testing of round bar test specimens subjected (at least remotely) to uniaxial loading in either force or strain control. The focus of the procedure is on tests in which creep and fatigue deformation and damage is generated simultaneously within a given cycle. Data which may be determined from creep-fatigue tests performed under such conditions may characterize (a) cyclic stress-strain deformation response (b) cyclic creep (or relaxation) deformation response (c) cyclic hardening, cyclic softening response or (d) cycles to crack formation, or both.
4.3 While there are a number of testing Standards and Codes of Practice that cover the determination of low cycle fatigue deformation and cycles to crack initiation properties (See Practice E...
SCOPE
1.1 This test method covers the determination of mechanical properties pertaining to creep-fatigue deformation or crack formation in nominally homogeneous materials, or both by the use of test specimens subjected to uniaxial forces under isothermal conditions. It concerns fatigue testing at strain rates or with cycles involving sufficiently long hold times to be responsible for the cyclic deformation response and cycles to crack formation to be affected by creep (and oxidation). It is intended as a test method for fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. The cyclic conditions responsible for creep-fatigue deformation and cracking vary with material and with temperature for a given material.
1.2 The use of this test method is limited to specimens and does not cover testing of full-scale components, structures, or consumer products.
1.3 This test method is primarily aimed at providing the material properties required for assessment of defect-free engineering structures containing features that are subject to cyclic loading at temperatures that are sufficiently high to cause creep deformation.
1.4 This test method is applicable to the determination of deformation and crack formation or nucleation properties as a consequence of either constant-amplitude strain-controlled tests or constant-amplitude force-controlled tests. It is primarily concerned with the testing of round bar test specimens subjected to uniaxial loading in either force or strain control. The focus of the procedure is on tests in which creep and fatigue deformation and damage is generated simultaneously within a given cycle. It does not cover block cycle testing in which creep and fatigue damage is generated sequentially. Data that may be determined from creep-fatigue tests performed under conditions in whic...
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Designation: E2714 − 09
StandardTest Method for
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Creep-Fatigue Testing
This standard is issued under the fixed designation E2714; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
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ε NOTE—The term “stress range” was moved from Definitions Specific to this Standard, 3.4 to Definitions, 3.3 in De-
cember 2011.
1. Scope under conditions in which creep-fatigue deformation and
damage is generated simultaneously include (a) cyclic stress-
1.1 Thistestmethodcoversthedeterminationofmechanical
strain deformation response (b) cyclic creep (or relaxation)
properties pertaining to creep-fatigue deformation or crack
deformation response (c) cyclic hardening, cyclic softening
formation in nominally homogeneous materials, or both by the
response (d) cycles to formation of a single crack or multiple
use of test specimens subjected to uniaxial forces under
cracks in test specimens.
isothermal conditions. It concerns fatigue testing at strain rates
or with cycles involving sufficiently long hold times to be
NOTE 1—Acrack is believed to have formed when it has nucleated and
propagated in a specimen that was initially uncracked to a specific size
responsible for the cyclic deformation response and cycles to
that is detectable by a stated technique. For the purpose of this standard,
crack formation to be affected by creep (and oxidation). It is
the formation of a crack is evidenced by a measurable increase in
intended as a test method for fatigue testing performed in
compliance of the specimen or by a size detectable by potential drop
support of such activities as materials research and
technique. Specific details of how to measure cycles to crack formation
development, mechanical design, process and quality control,
are described in 9.5.1.
product performance, and failure analysis. The cyclic condi-
1.5 Thistestmethodisapplicabletotemperaturesandstrain
tions responsible for creep-fatigue deformation and cracking
rates for which the magnitudes of time-dependent inelastic
vary with material and with temperature for a given material.
strains (creep) are on the same order or larger than time-
1.2 The use of this test method is limited to specimens and independent inelastic
does not cover testing of full-scale components, structures, or
NOTE 2—The term inelastic is used herein to refer to all nonelastic
consumer products.
strains. The term plastic is used herein to refer only to time dependant
(that is, non-creep) component of inelastic strain. A useful engineering
1.3 This test method is primarily aimed at providing the
estimate of time-independent strain can be obtained when the strain rate
material properties required for assessment of defect-free -3 -1
exceeds some value. For example, a strain rate of 1×10 sec is often
engineering structures containing features that are subject to
used for this purpose. This value should increase with increasing test
cyclicloadingattemperaturesthataresufficientlyhightocause measurement.
creep deformation.
1.6 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1.4 This test method is applicable to the determination of
standard.
deformation and crack formation or nucleation properties as a
consequence of either constant-amplitude strain-controlled
1.7 This standard does not purport to address all of the
tests or constant-amplitude force-controlled tests. It is primar-
safety concerns, if any, associated with its use. It is the
ily concerned with the testing of round bar test specimens
responsibility of the user of this standard to establish appro-
subjected to uniaxial loading in either force or strain control.
priate safety and health practices and determine the applica-
The focus of the procedure is on tests in which creep and
bility of regulatory limitations prior to use.
fatigue deformation and damage is generated simultaneously
within a given cycle. It does not cover block cycle testing in
2. Referenced Documents
whichcreepandfatiguedamageisgeneratedsequentially.Data
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2.1 ASTM Standards:
that may be determined from creep-fatigue tests performed
E4Practices for Force Verification of Testing Machines
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This test method is under the jurisdiction ofASTM Committee E08 on Fatigue
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and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Deformation and Fatigue Crack Formation. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
CurrenteditionapprovedNov.1,2009.PublishedDecember2009.DOI:10.1520/ Standards volume infor
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