ASTM E3098-17

Standard Test Method for Mechanical Uniaxial Pre-strain and Thermal Free Recovery of Shape Memory Alloys

SIGNIFICANCE AND USE
5.1 This test method is used to measure a specimen's material and shape memory effect properties in response to a uniaxial deformation and then cycling through a full thermal transformation to recover all or a portion of the deformation. A material's martensite stiffness, martensite residual strain, austenite recovered strain, and unrecovered strain (or plastic deformation) after thermal cycling is determined.  
5.2 Measurement of the specimen's motion 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. 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 after uniaxial pre-straining in the martensite state.  
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 applied stress.  
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 describes the heating and cooling a Shape Memory Alloy (SMA) specimen through transformation after uniaxial deformation to determine residual strain after loading and unloading, recovered strain on heating, total unrecovered strain upon cooling, and transformation temperatures.  
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: 31-Oct-2017
• 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 F2063-18 - Standard Specification for Wrought Nickel-Titanium Shape Memory Alloys for Medical Devices and Surgical Implants
• Effective Date: 01-Aug-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 E1169-17 - Standard Practice for Conducting Ruggedness Tests
• Effective Date: 01-Oct-2017
• Refers: ASTM E1169-17e1 - 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 F2082-15 - Standard Test Method for Determination of Transformation Temperature of Nickel-Titanium Shape Memory Alloys by Bend and Free Recovery
• Effective Date: 01-May-2015
• 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 E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E1169-14 - Standard Practice for Conducting Ruggedness Tests
• Effective Date: 01-May-2014

Overview

ASTM E3098-17: Standard Test Method for Mechanical Uniaxial Pre-strain and Thermal Free Recovery of Shape Memory Alloys provides a consistent methodology for evaluating the shape memory properties of Shape Memory Alloys (SMAs) subjected to mechanical deformation followed by thermal cycling. This test method is essential for determining key material characteristics, such as martensite stiffness, residual and recovered strain, and transformation temperatures, particularly in semiprocessed shapes like wire, tube, or strip. The test closely simulates many practical applications of SMAs, making its results directly relevant to industrial and research settings.

Key Topics

• Uniaxial Pre-strain and Thermal Recovery: The standard outlines the process of mechanically deforming an SMA specimen in its martensitic state, unloading it, and then heating and cooling it to evaluate its shape recovery capabilities and transformation behavior.
• Material Properties Assessed:
  • Martensite residual strain
  • Austenite recovered strain
  • Unrecovered (plastic) strain after thermal cycling
  • Transformation temperatures including martensite and austenite start and finish points
• Test Applicability: Designed primarily for wires, tubes, and strips, this method enables testing on semi-finished products and can also be used on trained or processed materials.
• Two-Way Shape Memory Effect: By cycling between martensite and austenite states without applied stress, the method can help determine the material’s two-way shape memory characteristics.
• Quality Control and Research: The method is ideal for specification acceptance, quality assurance, and comparative research studies.

Applications

This ASTM standard test method is widely valuable for industries and laboratories working with shape memory alloys, particularly nickel-titanium (Nitinol) and other thermoelastic alloys. Practical applications include:

• Product Qualification: Verifying the functional properties of SMAs in quality control before the final manufacturing stage.
• Material Characterization: Assessing the deformation and recovery characteristics needed for performance-sensitive applications such as medical devices, actuation systems, and morphing structures.
• Specification Acceptance: Providing a standardized result for supplier-customer agreements concerning semi-finished SMA components such as springs and actuator elements.
• Research and Development: Enabling consistent evaluation of experimental alloys or processing methods.

Note: The transformation temperatures obtained by this test may differ from those measured by other methods due to strain and stress effects.

Related Standards

ASTM E3098-17 references several key standards that together support comprehensive testing and characterization of SMAs:

• ASTM E4: Practices for Force Verification of Testing Machines
• ASTM E8/E8M: Test Methods for Tension Testing of Metallic Materials
• ASTM E9 & E209: Compression Testing of Metallic Materials at Room and Elevated Temperatures
• ASTM E21: Elevated Temperature Tension Testing of Metallic Materials
• ASTM E83: Extensometer Systems Verification and Classification
• ASTM E2368: Strain Controlled Thermomechanical Fatigue Testing
• ASTM F2004: Transformation Temperature of Nickel-Titanium Alloys by Thermal Analysis
• ASTM F2082, F2516: Additional methods for SMA properties and Nitinol tension testing
• ISO 9001: Quality Management Systems
• F2005, F2063: Terminology and specifications for nickel-titanium shape memory alloys

Practical Value

By following ASTM E3098-17, organizations benefit from:

• Consistent, repeatable measurement of shape memory effect properties
• Versatile application for different SMA forms and product stages
• Reliable data for quality assurance and performance validation

Keywords: ASTM E3098-17, Shape Memory Alloy, SMA testing, uniaxial pre-strain, thermal recovery, transformation temperature, martensite, austenite, quality control, Nitinol, mechanical 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: E3098 − 17
Standard Test Method for
Mechanical Uniaxial Pre-strain and Thermal Free Recovery
of Shape Memory Alloys
This standard is issued under the fixed designation E3098; 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 E29 Practice for Using Significant Digits in Test Data to
Determine Conformance with Specifications
1.1 This test method describes the heating and cooling a
E74 Practice of Calibration of Force-Measuring Instruments
Shape MemoryAlloy (SMA) specimen through transformation
for Verifying the Force Indication of Testing Machines
after uniaxial deformation to determine residual strain after
E83 Practice for Verification and Classification of Exten-
loading and unloading, recovered strain on heating, total
someter Systems
unrecovered strain upon cooling, and transformation tempera-
E177 Practice for Use of the Terms Precision and Bias in
tures.
ASTM Test Methods
1.2 Units—The values stated in SI units are to be regarded
E209 PracticeforCompressionTestsofMetallicMaterialsat
as standard. No other units of measurement are included in this
Elevated Temperatures with Conventional or Rapid Heat-
standard.
ing Rates and Strain Rates
1.3 This standard does not purport to address all of the E691 Practice for Conducting an Interlaboratory Study to
safety concerns, if any, associated with its use. It is the
Determine the Precision of a Test Method
responsibility of the user of this standard to establish appro- E1169 Practice for Conducting Ruggedness Tests
priate safety, health, and environmental practices and deter-
E2368 Practice for Strain Controlled Thermomechanical
mine the applicability of regulatory limitations prior to use. Fatigue Testing
1.4 This international standard was developed in accor-
F2004 Test Method for Transformation Temperature of
dance with internationally recognized principles on standard- Nickel-Titanium Alloys by Thermal Analysis
ization established in the Decision on Principles for the
F2005 Terminology for Nickel-Titanium Shape Memory
Development of International Standards, Guides and Recom- Alloys
mendations issued by the World Trade Organization Technical
F2063 Specification for Wrought Nickel-Titanium Shape
Barriers to Trade (TBT) Committee.
Memory Alloys for Medical Devices and Surgical Im-
plants
2. Referenced Documents F2082 Test Method for Determination of Transformation
2 Temperature of Nickel-Titanium Shape Memory Alloys
2.1 ASTM Standards:
by Bend and Free Recovery
E4 Practices for Force Verification of Testing Machines
F2516 Test Method for Tension Testing of Nickel-Titanium
E6 Terminology Relating to Methods of Mechanical Testing
Superelastic Materials
E8/E8M Test Methods for Tension Testing of Metallic Ma-
2.2 Other Standards:
terials
IEEE/ASTM SI 10 American National Standard for Metric
E9 Test Methods of Compression Testing of Metallic Mate-
Practice
rials at Room Temperature
ASQ C1 General Requirements for a Quality Program
E21 TestMethodsforElevatedTemperatureTensionTestsof
ISO 9001 Quality Management Systems—Requirements
Metallic Materials
3. Terminology
3.1 Definitions—Specific technical terms used in this test
This test method is under the jurisdiction ofASTM Committee E08 on Fatigue
method are found in Terminology F2005:
and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic
Deformation and Fatigue Crack Formation.
Current edition approved Nov. 1, 2017. Published March 2018. DOI: 10.1520/
E3098–17 Available fromAmerican 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
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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
E3098 − 17
3.2 austenite finish strain (e )—Strainattheaustenitefinish specimen to its fully martensite phase. During heating and
Af
temperature. cooling the extension or contraction of the specimen is
measured and plotted versus the specimen temperature.
3.3 austenite start strain (e )—Strain at the austenite start
As
temperature.
5. Significance and Use
3.4 initial Strain (e )—Specimen strain at LCT after nor-
5.1 This test method is used to measure a specimen’s
malizing (see 11.1) and prior to pre-straining the specimen.
material and shape memory effect properties in response to a
3.5 lower cycle temperature (LCT)—LCT is the minimum
uniaxial deformation and then cycling through a full thermal
temperatureofthethermalcycle.Itisselectedtobe10to30°C
transformation to recover all or a portion of the deformation.A
lower than M determined by a DSC test in accordance with
f
material’s martensite stiffness, martensite residual strain, aus-
Test Method F2004. However, the DSC test shall be done on
tenite recovered strain, and unrecovered strain (or plastic
the sample material in the same condition as the UPFR test
deformation) after thermal cycling is determined.
material.
5.2 Measurementofthespecimen’smotioncloselyparallels
3.6 maximum loading strain (e )—Maximum specimen
i
many shape memory applications and provides a result that is
strain during pre-straining at the LCT.
applicable to the function of the material.
3.7 recovery strain (e )—Is the amount of residual strain
rec
5.3 This test method may be used for, but is not limited to,
that is recovered in the specimen after heating to the UCT and
wire, round tube, or strip samples. It is able to provide an
cooling to the LCT following pre-straining, it is equal to the
assessment of the product in its semi-finished form.
unloaded strain (e ) minus strain at lower cycle temperature
u
(e ) after cooling from the UCT.
LCT
5.4 This test method provides a simple method for deter-
3.8 strain at lower cycle temperature (e )—Specimen mining transformation temperatures by heating and cooling
LCT
strain at the LCT after pre-straining and unloading at the LCT specimens through their full thermal transformation after
and heating to the UCT and cooling to LCT. uniaxial pre-straining in the martensite state.
3.9 strain at upper cycle temperature (e )—Specimen
5.5 This test method can be used on trained and processed
UCT
strain at the UCT after pre-straining and unloading at the LCT
material in a semi-finished form to measure Two Way Shape
and heating to the UCT.
Memory Effect by comparing the strain in the austenite state
and martensite states with no applied stress.
3.10 stress (S)—Stress is defined as the ratio of force to the
specimen original cross sectional area.
5.6 This test method is useful for quality control, specifica-
3.11 transformation strain (e )—The strain recovery due to tion acceptance, and research.
t
the austenitic transformation obtained when heating at a
5.7 Transformation temperatures derived from this test
specified stress. e 5e 2e
T As Af
method may not agree with those obtained by other test
3.12 two way strain (e )—SpecimenstrainattheLCTafter
methods due to the effects of strain and stress on the transfor-
TW
cooling from the UCT minus the strain at the UCT. This is the
mation.
strain induced in the shape memory alloy specimen when it is
5.8 Componentssuchasspringsorothersemi-finishedparts
cooled from UCT to LCT with an applied tensile stress of
canbetestedusingthismethodasagreeduponbythecustomer
7 MPa or less. e 5e 2e
TW LCT UCT
and supplier. Units of stress and strain can be replaced with
3.13 unloaded strain (e )—Specimen strain at LCT after
u
force and displacement.
pre-straining and then unloading, but prior to heating.
3.14 upper cycle temperature (UCT)—UCTisthemaximum 6. Interferences
temperatureofthethermalcycle.Itisselectedtobehigherthan
6.1 The initial condition of the test specimen can signifi-
the A determined by a DSC test in accordance with Test
f
cantly impact test results.
Method F2004. For example, a temperature between 10 to
NOTE 1—Care should be taken to assure the material is free of
100 °C above A may be selected in consideration of the strain
f
unintended residual stresses from fabrication, processing, or handling.
applied to the specimen. The DSC test shall be done on the
Cuttingandgrindingcancausecoldworkwhichaffectsthetransformation
sample material in the same condition as the UPFR test
temperatures. Oxidation during heat treatment can change the thermal
material.
properties of the specimen and affect the temperature uniformity. Such
effects are magnified by specimens with smaller gauge diameters.
3.15 Abbreviations:
3.15.1 UPFR—Uniaxial Pre-strain and Thermal Free Re- 6.2 Complete thermal transformation is required for accu-
rate results. The material’s martensite finish and austenite
covery
finish temperatures may be estimated prior to the test by
3.16 See also E4: General Terminology
Differential Scanning Calorimetry (Test Method F2004), or
4. Summary of Test Method Bend and Free Recovery (Test Method F2082).
4.1 This test method involves cooling a test specimen to its 6.3 Makesurethattheheatingandcoolingsystemmaintains
fully martensitic state, deforming the specimen to a defined a uniform specimen temperature within 6 3ºC, along the
strain under uniaxial loading, removing the force, heating the specimen length, over the gauge section. Temperature gradi-
specimen to its fully austenitic phase, and then cooling the ents in the specimen will affect the apparent transformation
E3098 − 17
temperatures and strains. Please see 10.1 for details on tem- 9. Calibration and Standardization
perature measurement.
9.1 The tension or compression testing system shall be
6.4 The heating and cooling rate for the test shall be
calibrated and verified according to Practices E4.
consistent with the sample thickness so that the test section of
9.2 An extensometer system shall be verified according to
the specimen is at a uniform temperature within 6 3ºC,
Practice E83 Class B-2. The strain signal of a mechanical
transverse to the specimen length, over the gauge section. See
extensometer will change as a function of temperature. See
10.1 for additional details on temperature measurement.
Practice E83, Appendix X2. To compensate for a thermally
induced shift in an extensometer a zero-force thermal strain
NOTE 2—Interferences 6.3 and 6.4 may be achieved by selecting hold
times at the UCTand LCTto insure the specimen and temperature control
compensation routine shall be used. The extensometer is
system are fully equilibrated before starting/continuing the thermal cycle.
attached to a specimen having a known coefficient of thermal
6.5 Transformation temperatures will
...