ASTM E2714-13(2020)
(Test Method)Standard Test Method for Creep-Fatigue Testing
Standard Test Method for Creep-Fatigue Testing
SIGNIFICANCE AND USE
4.1 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.
4.2 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 Pr...
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 whi...
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2714 − 13 (Reapproved 2020)
Standard Test Method for
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.
1. Scope strain deformation response (b) cyclic creep (or relaxation)
deformation response (c) cyclic hardening, cyclic softening
1.1 Thistestmethodcoversthedeterminationofmechanical
response (d) cycles to formation of a single crack or multiple
properties pertaining to creep-fatigue deformation or crack
cracks in test specimens.
formation in nominally homogeneous materials, or both by the
use of test specimens subjected to uniaxial forces under
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
isothermal conditions. It concerns fatigue testing at strain rates
that is detectable by a stated technique. For the purpose of this standard,
or with cycles involving sufficiently long hold times to be
the formation of a crack is evidenced by a measurable increase in
responsible for the cyclic deformation response and cycles to
compliance of the specimen or by a size detectable by potential drop
crack formation to be affected by creep (and oxidation). It is
technique. Specific details of how to measure cycles to crack formation
intended as a test method for fatigue testing performed in
are described in 9.5.1.
support of such activities as materials research and
1.5 Thistestmethodisapplicabletotemperaturesandstrain
development, mechanical design, process and quality control,
rates for which the magnitudes of time-dependent inelastic
product performance, and failure analysis. The cyclic condi-
strains (creep) are on the same order or larger than time-
tions responsible for creep-fatigue deformation and cracking
independent inelastic strain.
vary with material and with temperature for a given material.
NOTE 2—The term inelastic is used herein to refer to all nonelastic
1.2 The use of this test method is limited to specimens and
strains. The term plastic is used herein to refer only to time independent
does not cover testing of full-scale components, structures, or (that is, non-creep) component of inelastic strain. A useful engineering
estimate of time-independent strain can be obtained when the strain rate
consumer products.
-3 -1
exceeds some value. For example, a strain rate of 1×10 sec is often
1.3 This test method is primarily aimed at providing the
used for this purpose. This value should increase with increasing test
material properties required for assessment of defect-free temperature.
engineering structures containing features that are subject to
1.6 The values stated in SI units are to be regarded as
cyclicloadingattemperaturesthataresufficientlyhightocause
standard. No other units of measurement are included in this
creep deformation.
standard.
1.4 This test method is applicable to the determination of
1.7 This standard does not purport to address all of the
deformation and crack formation or nucleation properties as a
safety concerns, if any, associated with its use. It is the
consequence of either constant-amplitude strain-controlled
responsibility of the user of this standard to establish appro-
tests or constant-amplitude force-controlled tests. It is primar-
priate safety, health, and environmental practices and deter-
ily concerned with the testing of round bar test specimens
mine the applicability of regulatory limitations prior to use.
subjected to uniaxial loading in either force or strain control.
1.8 This international standard was developed in accor-
The focus of the procedure is on tests in which creep and
dance with internationally recognized principles on standard-
fatigue deformation and damage is generated simultaneously
ization established in the Decision on Principles for the
within a given cycle. It does not cover block cycle testing in
Development of International Standards, Guides and Recom-
whichcreepandfatiguedamageisgeneratedsequentially.Data
mendations issued by the World Trade Organization Technical
that may be determined from creep-fatigue tests performed
Barriers to Trade (TBT) Committee.
under conditions in which creep-fatigue deformation and
2. Referenced Documents
damage is generated simultaneously include (a) cyclic stress-
2.1 ASTM Standards:
E4Practices for Force Verification of Testing Machines
This test method is under the jurisdiction ofASTM Committee E08 on Fatigue
and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
Deformation and Fatigue Crack Formation. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2020. Published May 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2009. Last previous edition approved in 2013 as E2714–13. Standards volume information, refer to the standard’s Document Summary page on
DOI:10.1520/E2714–13R20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2714 − 13 (2020)
E8/E8MTest Methods for Tension Testing of Metallic Ma- ISO 7500-1–2004Metallic materials – Verification of static
terials uniaxial testing machines – Part 1. Tension/compression
E83Practice for Verification and Classification of Exten- testingmachines–Verificationandcalibrationoftheforce
someter Systems measuring system
E111Test Method for Young’s Modulus, Tangent Modulus, ISO 9513–1999Metallic materials – Calibration of exten-
and Chord Modulus someters used in axial testing
E139Test Methods for Conducting Creep, Creep-Rupture, ISO 5725–1994Accuracy (trueness and precision) of mea-
and Stress-Rupture Tests of Metallic Materials surement methods
E177Practice for Use of the Terms Precision and Bias in
2.5 JIS Standard:
ASTM Test Methods
JIS Z 2279–1992Method of high temperature low cycle
E220Test Method for Calibration of Thermocouples By
fatigue testing for metallic materials
Comparison Techniques
E230Specification for Temperature-Electromotive Force 3. Terminology
(emf) Tables for Standardized Thermocouples
3.1 Thedefinitionsinthistestmethodthatarealsoincluded
E467Practice for Verification of Constant Amplitude Dy-
in Terminology E1823 are in accordance with Terminology
namic Forces in an Axial Fatigue Testing System
E1823.
E606Test Method for Strain-Controlled Fatigue Testing
3.2 Symbols,standarddefinitions,anddefinitionsspecificto
E647Test Method for Measurement of Fatigue Crack
this standard are in 3.2.1, 3.3, and 3.4, respectively.
Growth Rates
3.2.1 Symbols:
E691Practice for Conducting an Interlaboratory Study to
Symbol Term
Determine the Precision of a Test Method
E1012Practice for Verification of Testing Frame and Speci-
d [L] Diameter of gage section
men Alignment Under Tensile and Compressive Axial
of cylindrical test specimen
D , [L] Diameter of grip ends
Force Application g
-2
E, E ,E ,[FL ] Elastic modulus, initial modulus
o N
E1823TerminologyRelatingtoFatigueandFractureTesting
of elasticity, modulus of elasticity at cycle
-2
E2368Practice for Strain Controlled Thermomechanical
E ,E [FL ] Tensile modulus,
T C
compressive modulus
Fatigue Testing
P [F] Force
2.2 BSI Standards:
l, l [L] Extensometer gage length,
o
original extensometer
BS 7270: 2000Method for ConstantAmplitude Strain Con-
gage length
trolled Fatigue Testing
L, L , [L] Length of parallel section
o
BS 1041-4:1992Temperature measurement – Part 4: Guide
of gage length, original length
of parallel section of gage length
to the selection and use of thermocouples
N, N Cycle number, cycle number
4 f
2.3 CEN Standards:
to crack formation
r,[L} Transition radius
EN 60584-1–1996Thermocouples – Reference tables (IEC
(from parallel section to grip end)
584-1)
ε ⁄ ε ,R Strain ratio
min max ε
EN 60584 -2– 1993Thermocouples – Tolerances (IEC
σ ⁄ σ ,R Stress ratio
min max σ
584-2) τ Time
T[θ] Specimen temperature
PrEN 3874–1998Test methods for metallic materials –
T [θ] Indicated specimen
i
constant amplitude force-controlled low cycle fatigue
temperature
N versus σ Crack formation or end-of-life criterion is
testing max
expressed as a percentage reduction in
PrEN 3988–1998Test methods for metallic materials –
maximum stress from the cycles,
constant amplitude strain-controlled low cycle fatigue
N versus σ curve when the stress
max
falls sharply (see Fig. 1), or a specific
testing
percentage
2.4 ISO Standards:
decrease in the modulus of elasticity ratios
in the tensile and compressive portions
ISO12106–2003Metallicmaterials–Fatiguetesting-Axial
of the hysteresis diagrams, or as a
strain-controlled method
specific increase in crack size as
ISO 12111–2005 (Draft) Strain-controlled thermo-
indicated by an electric
potential drop monitoring instrumentation.
mechanical fatigue testing method
ε, ε , ε Strain, maximum strain in the cycle,
max min
minimum strain in the cycle
ε , ε , ε Elastic strain amplitude,
ea pa ta
Available from British Standards Institute (BSI), 389 Chiswick High Rd.,
plastic strain amplitude,
London W4 4AL, U.K., http://www.bsi-global.com.
total strain amplitude
Available from European Committee for Standardization (CEN), 36 rue de
Stassart, B-1050, Brussels, Belgium, http://www.cenorm.be.
Available from International Organization for Standardization (ISO), 1, ch. de
la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:// Available from Japanese Standards Organization (JSA), 4-1-24 Akasaka
www.iso.ch. Minato-Ku, Tokyo, 107-8440, Japan, http://www.jsa.or.jp.
E2714 − 13 (2020)
-2
3.3.5 initial modulus of elasticity, E , [FL ]—The modu-
∆ε , ∆ε , ∆ε Elastic strain range, plastic strain range,
e p t o
total strain range (see Fig. 2)
lus of elasticity determined during the loading portion of the
∆ε Inelastic strain range, (see Fig. 2) is the sum of
in
first cycle.
the
plastic strain range and the creep strains
-2
3.3.6 modulus of elasticity at cycle N, (E , [FL ]—The
during the cycle; it is the distance on the N
strain axis between points of intersections
averageofthemodulusofelasticitydeterminedduringincreas-
of the strain axis and the extrapolated linear
ing load portion (see E in Fig. 2) and the decreasing load
c
regions of the hysteresis loops during
tensile and compressive unloadings portion (E in Fig. 2) of the hysteresis diagram for the N
T th
σ, σ , σ Stress, maximum stress in the cycle,
max min
cycle.
minimum stress in the cycle
∆σ Stress range -2
3.3.7 stress range, ∆σ , [FL ]—The difference between the
maximum and minimum stresses.
3.3.7.1 Discussion—For creep-fatigue tests, the difference
3.3 Definitions:
between the maximum and minimum stresses is called the
3.3.1 cycle—In fatigue, one complete sequence of values of
“peak stress range” and for tests conducted under strain
force(strain)thatisrepeatedunderconstantamplitudeloading
control, the difference between the stresses at the points of
(straining)
reversal of the control parameter is called the “relaxed stress
3.3.2 hold-time, τ [T]—In fatigue testing, the amount of
h
range” (see Fig. 2b).
time in the cycle where the controlled test variable (force,
strain, displacement) remains constant with time (Fig. 3).
3.4 Definitions of Terms Specific to This Standard:
3.3.2.1 Discussion—Hold- time(s) are typically placed at
3.4.1 DCPD and ACPD—Direct current and alternating
peakstressorstrainintensionand/orcompression,butcanalso
current electrical potential drop crack monitoring instrumenta-
be placed at other positions within the cycle.
tion.
3.3.3 total cycle period, τ [T],—The time for completion of
t
3.4.2 homologous temperature—The specimen temperature
one cycle.The parameter τ can be separated into hold (τ ) and
t h
in °K divided by the melting point of the material also in °K.
non-hold (τ ) (that is, steady and dynamic) components,
nh
where the total cycle time is the sum of the hold time and the
3.4.3 crack formation—A crack is believed to have formed
non-hold time.
when it has nucleated and propagated in a specimen that was
3.3.4 hysteresis diagram—The stress-strain path during one initially un-cracked to a size that is detectable by a stated
cycle (see Fig. 2). technique.
FIG. 1 Crack Formation and End-of-Test Criterion based on Reduction of Peak Stress for (a) Hardening and (b) Softening Materials
E2714 − 13 (2020)
FIG. 2 Examples of Stress-Strain Hysteresis Diagrams (a) Without Hold Time, (b) With Hold Time (Strain Control), (c) With Hold Time
(Force Control), see 3.2.1 for list of symbols.
4. Significance and Use of round bar test specimens subjected (at least remotely) to
uniaxial loading in either force or strain control. The focus of
4.1 Creep-fatigue testing is typically performed at elevated
the procedure is on tests in which creep and fatigue deforma-
temperatures and involves the sequential or simultaneous
tion and damage is generated simultaneously within a given
application of the loading conditions necessary to generate
cycle. Data which may be determined from creep-fatigue tests
cyclic deformation/damage enhanced by creep deformation/
performed under such conditions may characterize (a) cyclic
damage or vice versa. Unless such tests are performed in
stress-strain deformation response (b) cyclic creep (or relax-
vacuum or an inert environment, oxidation can also be respon-
ation) deformation response (c) cyclic hardening, cyclic soft-
sible for important interaction effects relating to damage
ening response or (d) cycles to crack formation, or both.
accumulation. The purpose of creep-fatigue tests can be to
determine material property data for (a) assessment input data
4.3 While there are a number of testing Standards and
for the deformation and damage condition analysis of engi-
Codes of Practice that cover the determination of low cycle
neering structures operating at elevated temperatures (b) the
fatigue deformation and cycles to crack initiation properties
verification of constitutive deformation and damage model
(See Practice E606, BS 7270: 2000, JIS Z 2279–1992, PrEN
effectiveness (c) material characterization, or (d) development
3874, 1998, PrEN 3988–1998, ISO 12106–2003, ISO
and verification of rules for new construction and life assess-
12111–2005, and Practice E2368-0
...
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