ASTM F2516-05

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Designation:F2516–05
Standard Test Method for
Tension Testing of Nickel-Titanium Superelastic Materials
This standard is issued under the fixed designation F 2516; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the tension testing of superelas-
tic nickel-titanium (nitinol) materials, specifically the methods
of determination of upper plateau strength, lower plateau
strength, residual elongation, tensile strength, and elongation.
1.2 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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
E6 Terminology Relating to Methods of Mechanical Test-
ing
E8 Test Methods for Tension Testing of Metallic Materials
FIG. 1 Terms Illustrated on Typical Stress-Strain Diagram of
E83 Practice for Verification and Classification of Exten- Superelastic Nitinol
someter System
E 111 Test Method forYoung’s Modulus,Tangent Modulus,
3.1.1 lower plateau strength (LPS)—the stress at 2.5 %
and Chord Modulus
strain during unloading of the sample, after loading to 6 %
E 1875 Test Method for Dynamic Young’s Modulus, Shear
strain.
Modulus, and Poisson’s Ratio by Sonic Resonance
3.1.2 residual elongation, El [%],—the strain after loading
r
F 2005 Terminology for Nickel-Titanium Shape Memory
to 6 % strain and unloading to 7 MPa.
Alloys
3.1.3 uniform elongation, El [%]—the elongation deter-
u
mined at the maximum force sustained by the test piece just
3. Terminology
prior to necking, or fracture, or both.
3.1 Definitions—The definitions of terms relating to tension
3.1.4 upper plateau strength (UPS)—the stress at 3 % strain
testing appearing in TerminologyE6 and the terms relating to
during loading of the sample.
nickel-titanium shape memory alloys appearing in Terminol-
4. Summary of Test Method
ogyF 2005shallbeconsideredasapplyingtothetermsusedin
this test method.Additional terms being defined are as follows
4.1 Using conventional tensile testing apparatus, the mate-
(see Fig. 1):
rial is pulled to 6 % strain, then unloaded to less than 7 MPa,
then pulled to failure.
This test method is under the jurisdiction ofASTM Committee F04 on Medical
5. Significance and Use
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
5.1 Tension tests provide information of the strength and
F04.15 on Material Test Methods.
Current edition approved Aug. 1, 2005. Published August 2005.
ductility of materials under uniaxial tensile stresses.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.2 Tension tests, as described in this test method, also
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
provide information on the superelasticity, as defined in Ter-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. minology F 2005, of the material at the test temperature.
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F2516–05
6. Apparatus 8.1.5 Upper plateau strength shall be determined by the
stress at a strain of 3.0 % during the initial loading of the
6.1 Apparatus is as described in Test MethodsE8.
specimen.
7. Test Specimen
8.1.6 Lower plateau strength shall be determined by the
stressatastrainof2.5 %duringtheunloadingofthespecimen.
7.1 Test specimens are as described in Test MethodsE8.
8.1.7 Residual elongation shall be determined by the differ-
8. Procedure
encebetweenthestrainatastressof7.0MPaduringunloading
and the strain at a stress of 7.0 MPa during loading.
8.1 Procedure shall be per Test Methods E8 with the
8.1.8 The uniform elongation shall be determined by elon-
following additions:
gation when the maximum load is reached just prior to necking
8.1.1 Unless otherwise specified, temperature of test shall
or fracture, or both.
be 22.0°C. Tolerance shall be 62.0°C.
8.1.2 Free-running crosshead speed shall be limited per
9. Report
Table 1.
8.1.3 Test shall consist of zeroing the force transducer, 9.1 The report shall include the following information,
gripping the specimen, pulling the specimen to 6
...