ASTM F2005-21

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: F2005 − 05 (Reapproved 2015) F2005 − 21
Standard Terminology for
Nickel-Titanium Shape Memory Alloys
This standard is issued under the fixed designation F2005; 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 terminology is a compilation of definitions of terms used in ASTM documents relating to nickel-titanium shape memory
alloys used for medical devices. This terminology includes only those terms for which ASTM either has standards or which are
used in ASTM standards for nickel-titanium shape memory alloys. It is not intended to be an all-inclusive list of terms related to
shape memory alloys.
1.2 Definitions that are similar to those published by another standards body are identified with abbreviations of the name of that
organization; for example, ICTAC is the International Confederation for Thermal Analysis and Calorimetry.
1.3 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:
E7 Terminology Relating to Metallography
E473 Terminology Relating to Thermal Analysis and Rheology
E3098 Test Method for Mechanical Uniaxial Pre-strain and Thermal Free Recovery of Shape Memory Alloys
F2004 Test Method for Transformation Temperature of Nickel-Titanium Alloys by Thermal Analysis
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
3. Terminology
active austenite finish temperature, n—term used to denote the austenite finish temperature of a finished an aged, shape-set
or tempered wire, tube, or component as determined by (1) a bend and free recovery method (BFR) method pursuant to Test
Method F2082, (2) by a uniform prestrain and free recovery (UPFR) method pursuant to Test Method E3098, or (3) another
method as agreed upon between purchaser and supplier rather than by DSC.calorimetry (DSC) pursuant to Test Method F2004.
age, v—to heat treat at a low to intermediate temperature, typically in the range of 300 °C to 575 °C, usually for an extended
period of time, to form precipitates and/or adjust transformation temperatures and thermoelastic properties.
This terminology is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.12 on Metallurgical Materials.
Current edition approved March 1, 2015March 1, 2021. Published May 2015March 2021. Originally approved in 2000. Last previous edition approved in 20102015 as
F2005 – 05 (2010).(2015). DOI: 10.1520/F2005-05R15.10.1520/F2005-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. 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
F2005 − 21
alloy phase, n—in a shape memory alloy, the crystal structure stable at a particular temperature and stress.
anneal, v—to heat treat in order to remove the effect of cold-working.at a temperature above the recrystallization temperature,
typically in the range of 700 °C to 950 °C, in order to essentially remove the effects of hot and/or cold working and dissolve
precipitates.
austenite, n—the high temperature parent phase in Ni-Ti shape memory alloys with a B2 crystal structure. This phase transforms
to R-phase or martensite on cooling.
austenite finish temperature (A ), n—the temperature at which the martensite to austenite transformation is completed on
f
heating in a single-stage transformation (Fig. 1) or the temperature at which the R-phase to austenite transformation is completed
on heating in a two-stage transformation (Fig. 2).
austenite peak temperature (A ) , ), n—the temperature of the endothermic peak position on the differential scanning
p
calorimeter (DSC) curve upon heating for the martensite to austenite transformation in a single-stage transformation (Fig. 1) or
the temperature of the endothermic peak position on the DSC curve upon heating for the R-phase to austenite transformation
in a two-stage transformation (Fig. 2).
austenite start temperature (A ) , ), n—the temperature at which the martensite to austenite transformation begins on heating
s
in a single-stage transformation (Fig. 1) or the temperature at which the R-phase to austenite transformation begins on heating
in a two-stage transformation (Fig. 2).
bend and free recovery (BFR), n—a test method for determining austenite transformation temperatures on heating.
DISCUSSION—
The test involves cooling a wire or tube specimen below the M temperature, deforming the specimen in a controlled fashion, then heating through
f
the austenite transformation. By measuring the shape memory response of the specimen A and A , temperatures can be determined. This test method
s f
is covered in Test Method F2082.
differential scanning calorimeter (DSC), n—a device that is capable of heating a test specimen and a reference at a controlled
rate and of automatically measuring the difference in heat flow between the specimen and the reference both to the required
sensitivity and precision.
differential scanning calorimetry (DSC), n—a technique in which the difference in heat flow into or out of a substance and
an inert reference is measured as a function of temperature while the substance and the reference material are subjected to a
controlled temperature program. This test method, as it applies to Ni-Ti shape memory alloys, is covered in Test Method F2004.
FIG. 1 DSC Graph for a Single-Stage Transformation
F2005 − 2
...