ASTM E2368-10(2017)
(Practice)Standard Practice for Strain Controlled Thermomechanical Fatigue Testing
Standard Practice for Strain Controlled Thermomechanical Fatigue Testing
SIGNIFICANCE AND USE
4.1 In the utilization of structural materials in elevated temperature environments, components that are susceptible to fatigue damage may experience some form of simultaneously varying thermal and mechanical forces throughout a given cycle. These conditions are often of critical concern because they combine temperature dependent and cycle dependent (fatigue) damage mechanisms with varying severity relating to the phase relationship between cyclic temperature and cyclic mechanical strain. Such effects can be found to influence the evolution of microstructure, micromechanisms of degradation, and a variety of other phenomenological processes that ultimately affect cyclic life. The strain-controlled thermomechanical fatigue test is often used to investigate the effects of simultaneously varying thermal and mechanical loadings under idealized conditions, where cyclic theoretically uniform temperature and strain fields are externally imposed and controlled throughout the gage section of the specimen.
SCOPE
1.1 This practice covers the determination of thermomechanical fatigue (TMF) properties of materials under uniaxially loaded strain-controlled conditions. A “thermomechanical” fatigue cycle is here defined as a condition where uniform temperature and strain fields over the specimen gage section are simultaneously varied and independently controlled. This practice is intended to address TMF testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. While this practice is specific to strain-controlled testing, many sections will provide useful information for force-controlled or stress-controlled TMF testing.
1.2 This practice allows for any maximum and minimum values of temperature and mechanical strain, and temperature-mechanical strain phasing, with the restriction being that such parameters remain cyclically constant throughout the duration of the test. No restrictions are placed on environmental factors such as pressure, humidity, environmental medium, and others, provided that they are controlled throughout the test, do not cause loss of or change in specimen dimensions in time, and are detailed in the data report.
1.3 The use of this practice is limited to specimens and does not cover testing of full-scale components, structures, or consumer products.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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.
General Information
Relations
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: E2368 − 10 (Reapproved 2017)
Standard Practice for
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Strain Controlled Thermomechanical Fatigue Testing
This standard is issued under the fixed designation E2368; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
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1.1 This practice covers the determination of thermome- 2.1 ASTM Standards:
E3 Guide for Preparation of Metallographic Specimens
chanicalfatigue(TMF)propertiesofmaterialsunderuniaxially
E4 Practices for Force Verification of Testing Machines
loaded strain-controlled conditions. A “thermomechanical”
E83 Practice for Verification and Classification of Exten-
fatigue cycle is here defined as a condition where uniform
someter Systems
temperature and strain fields over the specimen gage section
E111 Test Method for Young’s Modulus, Tangent Modulus,
are simultaneously varied and independently controlled. This
and Chord Modulus
practice is intended to address TMF testing performed in
E112 Test Methods for Determining Average Grain Size
support of such activities as materials research and
E220 Test Method for Calibration of Thermocouples By
development, mechanical design, process and quality control,
Comparison Techniques
product performance, and failure analysis. While this practice
E337 Test Method for Measuring Humidity with a Psy-
is specific to strain-controlled testing, many sections will
chrometer (the Measurement of Wet- and Dry-Bulb Tem-
provide useful information for force-controlled or stress-
peratures)
controlled TMF testing.
E467 Practice for Verification of Constant Amplitude Dy-
1.2 This practice allows for any maximum and minimum
namic Forces in an Axial Fatigue Testing System
values of temperature and mechanical strain, and temperature-
E606 Test Method for Strain-Controlled Fatigue Testing
mechanical strain phasing, with the restriction being that such
E1012 Practice for Verification of Testing Frame and Speci-
parameters remain cyclically constant throughout the duration
men Alignment Under Tensile and Compressive Axial
of the test. No restrictions are placed on environmental factors
Force Application
such as pressure, humidity, environmental medium, and others,
E1823 TerminologyRelatingtoFatigueandFractureTesting
provided that they are controlled throughout the test, do not
cause loss of or change in specimen dimensions in time, and
3. Terminology
are detailed in the data report.
3.1 The definitions in this practice are in accordance with
1.3 The use of this practice is limited to specimens and does
definitions given in Terminology E1823 unless otherwise
not cover testing of full-scale components, structures, or
stated.
consumer products.
3.2 Definitions:
1.4 The values stated in SI units are to be regarded as
3.2.1 Additional definitions are as follows:
standard. No other units of measurement are included in this
3.2.2 stress, σ—stressisdefinedhereintobetheengineering
standard.
stress, which is the ratio of force, P, to specimen original cross
sectional area, A:
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
σ 5 P/A (1)
ization established in the Decision on Principles for the
The area, A, is that measured in an unloaded condition at
Development of International Standards, Guides and Recom-
room temperature. See 7.2 for temperature state implications.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 3.2.3 coeffıcient of thermal expansion, α—the fractional
change in free expansion strain for a unit change in
temperature, as measured on the test specimen.
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This practice is under the jurisdiction ofASTM Committee E08 on Fatigue and
Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
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Deformation and Fatigue Crack Formation. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2017. Published December 2017. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
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approved in 2004. Last previous edition approved in 2010 as E2368–10 . DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E2368-10R17. the ASTM website.
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E2368 − 10 (2017)
3.2.4 total strain, ε—the st
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