ASTM E3097-23

Standard Test Method for Uniaxial Constant Force Thermal Cycling of Shape Memory Alloys

SIGNIFICANCE AND USE
5.1 Constant force thermal cycling tests determine the effect of stress on the transformation temperatures, recovered strain and residual strain of a shape memory alloy. The tests may be for one thermal cycle. A standard test method for force controlled repeated thermal cycling of shape memory alloys is currently under development.  
5.2 Measurement of the specimen's thermomechanical behavior closely parallels many shape memory applications and provides a result that is applicable to the function of the material.  
5.3 This test method may be used for, but is not limited to, wire, round tube, or strip samples. Thus it is able to provide an assessment of the product in its semi-finished form.  
5.4 This test method provides a simple method for determining transformation temperatures by heating and cooling specimens through their full thermal transformation under force.  
5.5 This test method can be used on trained and processed material in a semi-finished form to measure Two Way Shape Memory Effect by comparing the strain in the austenite state and martensite states with no minimal applied stress. The force is set to a minimum value not to exceed a corresponding stress of 7 MPa (in accordance Test Method F2516).  
5.6 This test method is useful for quality control, specification acceptance, and research.  
5.7 Transformation temperatures derived from this test method may not agree with those obtained by other test methods due to the effects of strain and stress on the transformation.  
5.8 Components such as springs or other semi-finished parts can be tested using this method as agreed upon by the customer and supplier. Units of stress and strain can be replaced with force and displacement.
SCOPE
1.1 This test method defines procedures for thermomechanical cycling of shape memory alloy (SMA) material and components under constant force. This method characterizes the transformation properties such as transformation temperatures, actuation strain and residual strain, when a SMA is thermally cycled through the phase transformation under a constant applied force. This test is done to provide data for the selection of SMA materials, quality control, design allowables and actuator design.  
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 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

• Status: Published
• Publication Date: 14-Jun-2023
• ICS: 77.120.99 - Other non-ferrous metals and their alloys
• Technical Committee: E08 - Fatigue and Fracture
• Drafting Committee: E08.05 - Cyclic Deformation and Fatigue Crack Formation

Relations

• Refers: ASTM E8/E8M-24 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM E1169-18 - Standard Practice for Conducting Ruggedness Tests
• Effective Date: 01-Sep-2018
• Refers: ASTM E209-18 - Standard Practice for Compression Tests of Metallic Materials at Elevated Temperatures with Conventional or Rapid Heating Rates and Strain Rates
• Effective Date: 01-Feb-2018
• Refers: ASTM F2004-17 - Standard Test Method for Transformation Temperature of Nickel-Titanium Alloys by Thermal Analysis
• Effective Date: 01-Oct-2017
• Refers: ASTM E1169-17e1 - Standard Practice for Conducting Ruggedness Tests
• Effective Date: 01-Oct-2017
• Refers: ASTM E1169-17 - Standard Practice for Conducting Ruggedness Tests
• Effective Date: 01-Oct-2017
• Refers: ASTM F2004-16 - Standard Test Method for Transformation Temperature of Nickel-Titanium Alloys by Thermal Analysis
• Effective Date: 01-Dec-2016
• Refers: ASTM E8/E8M-16 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 15-Jul-2016
• Refers: ASTM E8/E8M-15 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Feb-2015
• Refers: ASTM F2516-14 - Standard Test Method for Tension Testing of Nickel-Titanium Superelastic Materials
• Effective Date: 01-Oct-2014
• Refers: ASTM E4-14 - Standard Practices for Force Verification of Testing Machines
• Effective Date: 01-Jun-2014
• Refers: ASTM E1169-14 - Standard Practice for Conducting Ruggedness Tests
• Effective Date: 01-May-2014
• Refers: ASTM E8/E8M-13 - Standard Test Methods for Tension Testing of Metallic Materials
• Effective Date: 01-Jun-2013
• Refers: ASTM E1169-13a - Standard Practice for Conducting Ruggedness Tests
• Effective Date: 15-May-2013
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013

Overview

ASTM E3097-23: Standard Test Method for Uniaxial Constant Force Thermal Cycling of Shape Memory Alloys sets forth procedures to evaluate the thermomechanical behavior of shape memory alloys (SMA) and their components by subjecting them to repeated temperature cycles under a constant uniaxial force. This test method characterizes key transformation properties, including transformation temperatures, actuation strain, and residual strain, when SMAs are cycled through their phase transformation. Performance data obtained through this procedure support the selection of SMA materials, actuator design, quality control, and research applications.

This standard covers semi-finished product forms such as wire, round tube, or strip samples. It is typically used to determine how stress and thermal cycling influence transformation parameters critical to the function of the material, aligning closely with real-world SMA applications.

Key Topics

• Transformation Temperature Determination: This method enables the determination of key transformation temperatures under applied force, particularly for the austenite and martensite states, vital for the design and control of shape memory devices.
• Measurement of Actuation and Residual Strain: The method provides direct readings of actuation strain (strain recovery during transformation) and residual strain (deformation remaining after cycling).
• Applicability to Semi-finished Products: Widely used for SMAs in semi-finished forms, such as wires and strips, ensuring suitability before fabrication into final components.
• Testing Procedure:
  • Specimens are subjected to controlled heating and cooling between defined upper and lower cycle temperatures under a static force.
  • Strains are measured throughout the cycles to determine transformation characteristics.
• Two-Way Shape Memory Effect: The protocol supports assessment of the two-way shape memory effect by analyzing strain differences in austenite and martensite states at minimal applied stress.

Applications

• Material Selection for Actuators: Provides essential data on transformation temperatures and strains, enabling engineers to select appropriate SMA materials for actuators and thermomechanical applications.
• Quality Control: Used by manufacturers to ensure SMA products meet specified thermomechanical performance criteria prior to shipment.
• Research and Development: Supports research efforts in SMA formulation, heat treatment, or mechanical processing by quantifying the effects on transformation properties.
• Component Testing: Useful for verifying the compliance of springs and other semi-finished SMA components as agreed by the customer and supplier.
• Specification Compliance & Acceptance: Offers a standardized approach for acceptance testing to verify conformance with material specifications.

Related Standards

• ASTM F2004 – Test Method for Transformation Temperature of Nickel-Titanium Alloys by Thermal Analysis
• ASTM F2082 – Test Method for Determination of Transformation Temperature by Bend and Free Recovery
• ASTM F2516 – Test Method for Tension Testing of Nickel-Titanium Superelastic Materials
• ASTM E8/E8M – Test Methods for Tension Testing of Metallic Materials
• ASTM E21 – Test Methods for Elevated Temperature Tension Tests of Metallic Materials
• ISO 9001 – Quality Management Systems Requirements

These related standards provide additional methodologies and terminology, supporting comprehensive evaluation and consistent quality of shape memory alloys.

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Optimized for search terms such as shape memory alloy thermal cycling, ASTM E3097-23, SMA test methods, transformation temperature testing, and uniaxial constant force SMA testing.

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: E3097 − 23
Standard Test Method for
Uniaxial Constant Force Thermal Cycling of Shape Memory
Alloys
This standard is issued under the fixed designation E3097; 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 E9 Test Methods of Compression Testing of Metallic Mate-
rials at Room Temperature
1.1 This test method defines procedures for thermomechani-
E21 Test Methods for Elevated Temperature Tension Tests of
cal cycling of shape memory alloy (SMA) material and
Metallic Materials
components under constant force. This method characterizes
E83 Practice for Verification and Classification of Exten-
the transformation properties such as transformation
someter Systems
temperatures, actuation strain and residual strain, when a SMA
E209 Practice for Compression Tests of Metallic Materials at
is thermally cycled through the phase transformation under a
Elevated Temperatures with Conventional or Rapid Heat-
constant applied force. This test is done to provide data for the
ing Rates and Strain Rates
selection of SMA materials, quality control, design allowables
E691 Practice for Conducting an Interlaboratory Study to
and actuator design.
Determine the Precision of a Test Method
1.2 Units—The values stated in SI units are to be regarded
E1169 Practice for Conducting Ruggedness Tests
as standard. No other units of measurement are included in this
E2368 Practice for Strain Controlled Thermomechanical
standard.
Fatigue Testing
1.3 This standard does not purport to address all of the
F2004 Test Method for Transformation Temperature of
safety concerns, if any, associated with its use. It is the Nickel-Titanium Alloys by Thermal Analysis
responsibility of the user of this standard to establish appro-
F2005 Terminology for Nickel-Titanium Shape Memory
priate safety, health, and environmental practices and deter- Alloys
mine the applicability of regulatory limitations prior to use.
F2516 Test Method for Tension Testing of Nickel-Titanium
1.4 This international standard was developed in accor- Superelastic Materials
dance with internationally recognized principles on standard-
2.2 Other Standards:
ization established in the Decision on Principles for the
IEEE/ASTM SI 10 American National Standard for Metric
Development of International Standards, Guides and Recom-
Practice
mendations issued by the World Trade Organization Technical
ASQ C1 general Requirements for a Quality program
Barriers to Trade (TBT) Committee.
ISO 9001 Quality Management Systems—Requirements
2. Referenced Documents
3. Terminology
2.1 ASTM Standards:
3.1 Specific technical terms used in this test method are
E4 Practices for Force Calibration and Verification of Test-
found in Terminology F2005.
ing Machines
3.2 Definitions:
E6 Terminology Relating to Methods of Mechanical Testing
3.2.1 actuation strain (e )—The full strain recovery ob-
act
E8/E8M Test Methods for Tension Testing of Metallic Ma-
tained when heating from LCT to UCT at a specified stress. It
terials
includes the thermal expansions of martensite and austenite as
well the phase transformation strain. e 5e 2e
act LCT UCT
This test method is under the jurisdiction of ASTM Committee E08 on Fatigue
3.2.2 austenite 50 % (A )—Temperature at which the trans-
and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
formation from martensite to austenite is 50 % completed.
Deformation and Fatigue Crack Formation.
Current edition approved June 15, 2023. Published July 2023. Originally
approved in 2017. Last previous edition approved in 2017 as E3097–17. DOI:
10.1520/E3097–17 Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 4th Floor, New York, NY 10036, http://www.ansi.org.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Available from International Organization for Standardization (ISO), ISO
Standards volume information, refer to the standard’s Document Summary page on Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
the ASTM website. Geneva, Switzerland, http://www.iso.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E3097 − 23
A 5 A 1 A ⁄2. M 5 M 1 M ⁄2.
~ ! ~ !
50 s f 50 s f
3.2.3 austenite finish strain (e )—Strain calculated at the 3.2.12 martensite finish strain (e )—Strain calculated at
Af Mf
austenite finish temperature during final heating. the martensite finish temperature during cooling. (See Figure
1)
3.2.4 austenite start strain (e )—Strain calculated at the
As
austenite start temperature during final heating.
3.2.13 martensite start strain (e )—Strain calculated at the
Ms
martensite start temperature during cooling.
3.2.5 cooling transformation strain (e )—The strain recov-
ct
ery due to the martensitic transformation obtained when
3.2.14 residual strain (e )—The final strain at the upper
res
cooling at a specified stress. e 5e 2e cycle temperature minus the initial strain at the upper cycle
ct Ms Mf
temperature. e 5e 2e
3.2.6 heating transformation strain (e )—The strain recov- res UCT i
t
ery due to the austenitic transformation obtained when heating
3.2.15 strain at the lower cycle temperature (e )—
LCT
at a specified stress. e 5e 2e
Specimen strain at the LCT after cooling from the UCT to the
t As Af
LCT under the specified stress. (See Fig. 1.)
3.2.7 hysteresis width (HWIDTH)—Width of the thermal
hysteresis curve in degrees centigrade. Distance on the tem-
3.2.16 strain at the upper cycle temperature (e )—
UCT
perature axis between a vertical line drawn through the A
Specimen strain at the UCT after cooling to the LCT and
point and a vertical line drawn through the M point.
heating to the UCT at the specified stress. (See Fig. 1.)
3.2.8 initial loading strain (e )—Initial specimen strain after
3.2.17 thermal transformation span (TSPAN)—Thermal
i
normalization and before cooling when loaded at the UCT.
transformation span in degrees centigrade at a specified stress.
Distance on the temperature axis between a vertical line drawn
3.2.9 initial strain (e )—Specimen strain at UCT after
through the A point and a vertical line drawn through the M
normalizing (see 11.1) and prior to loading the specimen.
f f
point. TSPAN5A 2M .
f f
3.2.10 lower cycle temperature (LCT)—Minimum tempera-
3.2.18 upper cycle temperature (UCT)—The maximum
ture of the thermal cycle.
temperature of the thermal cycle.
3.2.11 martensite 50 % (M )—Temperature at which the
transformation from austenite to martensite is 50 % completed. 3.3 Abbreviations:
FIG. 1 Typical Constant Force Thermal Cycle and Test Methods Terms
E3097 − 23
3.3.1 UCFTC—Uniaxial Constant Force Thermal Cycling 6.2 When testing wire, make sure that the gripping mecha-
nism does not cause errors in strain measurement, for example
3.4 See also Terminology E6.
slipping in the grips.
4. Summary of Test Method
6.3 For tension and compression testing the extensometer
design and size shall be chosen so that the extensometer
4.1 Using a conventional uniaxial tension or compression
measures all deformation within the reduced gauge length of
testing apparatus (or a dead weight loading system) with a
the sample.
temperature control chamber (or other system for heating and
cooling at a controlled rate) the material is heated to the UCT,
6.4 Complete thermal transformation is required for accu-
above the austenite finish (A ) temperature, loaded to a speci-
f rate results. The material’s martensite finish and austenite
fied stress, then cooled to the LCT, a temperature below the
finish temperatures may be estimated prior to the test by
martensite finish (M ) temperature, and then heated to the UCT.
f Differential Scanning Calorimetry (Test Method F2004).
6.5 Make sure that the heating and cooling system maintains
5. Significance and Use
a uniform specimen temperature within 6 3 °C, along the
5.1 Constant force thermal cycling tests determine the effect
specimen length, over the gauge section. Temperature gradi-
of stress on the transformation temperatures, recovered strain
ents in the specimen will affect the apparent transformation
and residual strain of a shape memory alloy. The tests may be
temperatures and strains. See 10.1 for details on temperature
for one thermal cycle. A standard test method for force
measurement.
controlled repeated thermal cycling of shape memory alloys is
6.6 The heating and cooling rate for the test shall be
currently under development.
consistent with the sample thickness so that the test section of
5.2 Measurement of the specimen’s thermomechanical be-
the specimen is at a uniform temperature within 6 3 °C,
havior closely parallels many shape memory applications and
transverse to the specimen length, over the gauge section. See
provides a result that is applicable to the function of the
10.1 for details on temperature measurement.
material.
NOTE 2—Requirements specified in interferences 6.5 and 6.6 may be
5.3 This test method may be used for, but is not limited to,
achieved by selecting hold times at the UCT and LCT to ensure the
wire, round tube, or strip samples. Thus it is able to provide an
specimen and temperature control system are fully equilibrated before
starting/continuing the thermal cycle.
assessment of the product in its semi-finished form.
6.7 Make sure the specimen is fully austenitic at the upper
5.4 This test method provides a simple method for deter-
cycle temperature (UCT) for all stress levels to be tested. This
mining transformation temperatures by heating and cooling
is shown graphically in Fig. 2. It is selected to be higher than
specimens through their full thermal transformation under
the A determined by a DSC test per Test Method F2004. For
force. f
example, a temperature between 10 °C to 100 °C above A may
f
5.5 This test method can be used on trained and processed
be selected in consideration of the stress applied to the
material in a semi-finished form to measure Two Way Shape
specimen. The DSC test shall be done on the sample material
Memory Effect by comparing the strain in the austenite state
from the same lot and with the same thermomechanical history
and martensite s
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E3097 − 17 E3097 − 23
Standard Test Method for
Mechanical Uniaxial Constant Force Thermal Cycling of
Shape Memory Alloys
This standard is issued under the fixed designation E3097; 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
1.1 This test method defines procedures for determining the transformation temperatures, the related strains and the residual strain
when a shape memory alloy thermomechanical cycling of shape memory alloy (SMA) material and components under constant
force. This method characterizes the transformation properties such as transformation temperatures, actuation strain and residual
strain, when a SMA is thermally cycled under an applied axial stress. through the phase transformation under a constant applied
force. This test is done to provide data for the design and selection of shape memory alloy thermoelastic actuators.selection of SMA
materials, quality control, design allowables and actuator design.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
E4 Practices for Force Calibration and Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E8/E8M Test Methods for Tension Testing of Metallic Materials
E9 Test Methods of Compression Testing of Metallic Materials at Room Temperature
E21 Test Methods for Elevated Temperature Tension Tests of Metallic Materials
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E74 Practices for Calibration and Verification for Force-Measuring Instruments
E83 Practice for Verification and Classification of Extensometer Systems
E209 Practice for Compression Tests of Metallic Materials at Elevated Temperatures with Conventional or Rapid Heating Rates
and Strain Rates
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
This test method is under the jurisdiction of ASTM Committee E08 on Fatigue and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
Deformation and Fatigue Crack Formation.
Current edition approved Nov. 1, 2017June 15, 2023. Published March 2018July 2023. Originally approved in 2017. Last previous edition approved in 2017 as E3097–17.
DOI: 10.1520/E3097–17
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E3097 − 23
E1169 Practice for Conducting Ruggedness Tests
E2368 Practice for Strain Controlled Thermomechanical Fatigue Testing
F2004 Test Method for Transformation Temperature of Nickel-Titanium Alloys by Thermal Analysis
F2005 Terminology for Nickel-Titanium Shape Memory Alloys
F2063 Specification for Wrought Nickel-Titanium Shape Memory Alloys for Medical Devices and Surgical Implants
F2082 Test Method for Determination of Transformation Temperature of Nickel-Titanium Shape Memory Alloys by Bend and
Free Recovery
F2516 Test Method for Tension Testing of Nickel-Titanium Superelastic Materials
2.2 Other Standards:
IEEE/ASTM SI 10 American National Standard for Metric Practice
ASQ C1 general Requirements for a Quality program
ISO 9001 Quality Management Systems—Requirements
3. Terminology
3.1 Specific technical terms used in this test method are found in Terminology F2005.
3.2 Definitions:
3.2.1 actuation strastrainin (eact)— (e )—The full strain recovery obtained when heating from LCT to UCT at a specified stress.
act
It includes the thermal expansions of martensite and austenite as well the phase transformation strain. e 5e 2e
act LCT UCT
3.2.2 austenite50% (A50)— 50 % (A )—Temperature at which the transformation from martensite to austenite is 50%50 %
completed. A 5~A 1 A !⁄2.
50 s f
3.2.3 austenite finish strain (e )—Strain calculated at the austenite finish temperature. temperature during final heating.
Af
3.2.4 austenite start strain (e )—Strain calculated at the austenite start temperature.temperature during final heating.
As
3.2.5 cooling transformation strain (e )—The strain recovery due to the martensitic transformation obtained when cooling at a
ct
specified stress. e 5e 2e
ct Ms Mf
3.2.6 heating transformation strain (e )—The strain recovery due to the austenitic transformation obtained when heating at a
t
specified stress. e 5e 2e
t As Af
3.2.7 hysteresis width (HWIDTH)—Width of the thermal hysteresis curve in degrees centigrade. Distance on the temperature axis
between a vertical line drawn through the A point and a vertical line drawn through the M point.
50 50
3.2.8 initial loading strain (e )—Initial specimen strain after normalization and before cooling when loaded at the UCT.
i
3.2.9 initial strain (e )—Specimen strain at UCT after normalizing (see 11.1) and prior to loading the specimen.
3.2.10 lower cycle temperature (LCT)—Minimum temperature of the thermal cycle. It is selected to be 10 to 30°C lower than M
f
determined by a DSC test per Test Method F2004. However, the DSC test shall be done on the sample material in the same
condition as the UCFTC test material.
3.2.11 martensite 50%50 % (M )—Temperature at which the transformation from austenite to martensite is 50%50 % completed.
M 5 M 1 M ⁄2.
~ !
50 s f
3.2.12 initial loadingmartensite finish strain (e )—Initial specimen strain after normalization and before cooling when loaded at
iMf
the UCT.Strain calculated at the martensite finish temperature during cooling. (See Figure 1)
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
Switzerland, http://www.iso.org.
E3097 − 23
3.2.13 martensite start strain (e )—Strain calculated at the martensite start temperature during cooling.
Ms
3.2.14 residual strain (e )—The final strain at the upper cycle temperature minus the initial strain at the upper cycle temperature.
res
e 5e 2e
res UCT i
3.2.15 strain at the lower cycle temperature (e )—Specimen strain at the LCT after cooling from the UCT to the LCT under
LCT
the specified stress. (See Fig. 1.)
3.2.16 strain at the upper cycle temperature (e )—Specimen strain at the UCT after cooling to the LCT and heating to the UCT
UCT
at the specified stress. (See Fig. 1.)
3.2.17 thermal transformation span (TSPAN)—Thermal transformation span in degrees centigrade at a specified stress. Distance
on the temperature axis between a vertical line drawn through the AfA point and a vertical line drawn through the M point.
f f
TSPAN5A 2M .
f f
3.2.14 transformation strain (e )—The strain recovery due to the austenitic transformation obtained when heating at a specified
t
stress. e 5e 2e
T As Af
3.2.18 upper cycle temperature (UCT)—The maximum temperature of the thermal cycle. It is selected to be higher than the A
f
determined by a DSC test per Test Method F2004. For example, a temperature between 10 to 100 °C above A may be selected
f
in consideration of the stress applied to the specimen. The DSC test shall be done on the sample material in the same condition
as the UCFTC test material.
FIG. 1 Typical Constant Force Thermal Cycle and Test Methods Terms
E3097 − 23
3.3 Abbreviations:
3.3.1 UCFTC—Uniaxial Constant Force Thermal Cycling
3.4 See also Terminology E6.
4. Summary of Test Method
4.1 Using a conventional uniaxial tension or compression testing apparatus (or a dead weight loading system) with a temperature
control chamber (or other system for heating and cooling at a controlled rate) the material is heated to the UCT, above the austenite
finish (A ) temperature, loaded to a specified stress, then cooled to the LCT, a temperature below the martensite finish (M )
f f
temperature, and then heated to the UCT.
5. Significance and Use
5.1 Constant force thermal cycling tests determine the effect of stress on the transformation temperatures, recovered strain and
residual strain of a shape memory alloy. The tests may be for one thermal cycle but may involve repeated thermal cycles with the
number of cycles increasing by orders of magnitude 10 until the response of the material to thermal cycling no longer changes.
cycle. A standard test method for force controlled repeated thermal cycling of shape memory alloys is currently under development.
5.2 Measurement of the specimen’s thermomechanical behavior closely parallels many shape memory applications and provides
a result that is applicable to the function of the material.
5.3 This test method may be used for, but is not limited to, wire, round tube, or strip samples. Thus it is able to provide an
assessment of the product in its semi-finished form.
5.4 This test method provides a simple method for determining transformation temperatures by heating and cooling specimens
through their full thermal transformation under force.
5.5 This test method can be used on trained and processed material in a semi-finished form to measure Two Way Shape Memory
Effect by comparing the strain in the austenite state and martensite states with no minimal applied stress. The force is set to a
minimum value not to exceed a corresponding stress of 7 MPa (in accordance Test Method F2516).
5.6 This test method is useful for quality control, specification acceptance, and research.
5.7 Transformation temperatures derived from this test method may not agree with those obtained by other test methods due to
the effects of strain and stress on the transformation.
5.8 Components such as springs or other semi-finished parts can be tested using this method as agreed upon by the customer and
supplier. Units of stress and strain can be replaced with force and displacement.
6. Interferences
6.1 The initial condition of the test specimen can significantly impact test results.
NOTE 1—Care should be taken to assure the material is free of unintended residual stresses from fabrication, processing, or handling. Cutting and grinding
can cause cold work which affects the transformation temperatures. Oxidation during heat treatment can change the thermal properties of the specimen
and affect the temperature uniformity. Such effects are magnified by specimens with smaller gauge diameters.
6.2 When testing wire, make sure that the gripping mechanism does not cause errors in strai
...