ASTM F2004-17

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: F2004 − 16 F2004 − 17
Standard Test Method for
Transformation Temperature of Nickel-Titanium Alloys by
Thermal Analysis
This standard is issued under the fixed designation F2004; 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 of nickel-titanium shape memory
alloys, produced in accordance with Specification F2063, by differential scanning calorimetry.
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 appropriate safety safety, health, and healthenvironmental practices and to 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:
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E473 Terminology Relating to Thermal Analysis and Rheology
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E967 Test Method for Temperature Calibration of Differential Scanning Calorimeters and Differential Thermal Analyzers
E1142 Terminology Relating to Thermophysical Properties
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
3. Terminology
3.1 Specific technical terms used in this test method are found in Terminologies E473, E1142, and F2005.
4. Summary of Test Method
4.1 This test method involves heating and cooling a test specimen at a controlled rate in a controlled environment through the
temperature interval of the phase transformation. The difference in heat flow between the test material and a reference material due
to energy changes is continuously monitored and recorded. Absorption of energy due to a phase transformation in the specimen
results in an endothermic peak on heating. Release of energy due to a phase transformation in the specimen results in an exothermic
peak on cooling.
5. Significance and Use
5.1 Differential scanning calorimetry provides a rapid method for determining the transformation temperature(s) of nickel-
titanium shape memory alloys.
This test method is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.15 on Material Test Methods.
Current edition approved Dec. 1, 2016Oct. 1, 2017. Published January 2017October 2017. Originally approved in 2000. Last previous edition approved in 20102016 as
F2004 – 05 (2010).F2004 – 16. DOI: 10.1520/F2004-16.10.1520/F2004-17.
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
F2004 − 17
5.2 This test method uses small, stress-free, annealed samples to determine whether a sample of nickel-titanium alloy containing
nominally 54.5 to 56.5 %57.0 % nickel by weight is austenitic or martensitic at a particular temperature. Since chemical analysis
of these alloys does not have sufficient precision to determine the transformation temperature by measuring the nickel-to-titanium
ratio of the alloy, direct measurement of the transformation temperature of an annealed sample of known thermal history is
recommended.
5.3 This test method is useful for quality control, specification acceptance, and research.
5.4 Transformation temperatures derived from differential scanning calorimetry (DSC) may not agree with those obtained by
other test methods due to the effects of strain and load on the transformation. For example, transformation temperatures measured
in accordance with Test Method F2082 will differ from those measured by the current standard.
5.5 The use of this test method for finished or semi-finished components without annealing (as in 8.2) shall be agreed upon
between the purchaser and the supplier.
6. Interferences
6.1 Make sure the material to be tested is homogeneous since milligram sample quantities are used.
6.2 Take care in preparing the sample (1). Cutting and grinding can cause localized heating and/or deformation, that affect the
transformation temperature. Oxidation during heat treatment can change the thermal conductance of the sample.
6.3 Set the gas flow to provide adequate thermal conductivity in the test cell.
7. Apparatus
7.1 Use a differential scanning calorimeter capable of heating and cooling at rates up to 10°C/min and of automatically
recording the differential energy input between the specimen and the reference to the required sensitivity and precision.
7.2 Use sample capsules or pans composed of aluminum or other inert material of high thermal conductivity.
7.3 Use helium gas purge supply. See 10.3.1.
7.4 Use an analytical balance with a capacity of 100 mg capable of weighing to the nearest 0.1 mg.
8. Sampling
8.1 Use a sample size of 25 to 45 mg. Cut the sample to maximize surface contact with the (DSC) sample pan.
8.2 Anneal the sample at 800 to 850°C for 15 to 60 min in vacuum or inert atmosphere, or in air with adequate protection from
oxidation. Rapidly cool the sample to prevent precipitation of phases that may change the transformation temperature of the alloy.
For example, bare 25-45 mg samples can be air cooled after solution annealing.
8.3 Clean the sample of all foreign materials such as cutting fluid. If the sample is oxidized during heat treatment, grind, polish,
or etch the sample to remove the oxide. Take care to avoid cold working the sample as this will change its thermal response. Slight
oxidation is permissible but remove all heavy oxide scale.
9. Calibration
9.1 Calibrate the temperature axis of the instrument using the same heating rate, purge gas, and flow rate as those used for
analyzing the specimen in accordance with Test Method E967.
FIG. 1 DSC Curve for Nickel-Titanium (NiTi)
F2004 − 17
10. Procedure
10.1 Place the sample on the sample pan and place the pan on the test pedestal.
10.2 Place an empty pan on the reference pedestal.
10.3 Turn on the purge gas at a flow rate of 10 to 50 mL/min.
10.3.1 Use helium as the purge gas for the sample chamber.
10.3.2 Use a dry air, helium, or nitrogen cover gas. The dry gas shall have a dew point below the lowest temperature of the
cooling cycle.
10.4 Run the cooling and heating program.
10.4.1 Use the heating and cooling rates of 10 6 0.5°C/min.
10.4.2 Heat the sample from room temperature to a temperature of at least A + 30°C; hold at that temperature for a time
f
sufficient to equilibrate the sample with the furnace.
10.4.3 Cool the sample to a temperature of below M – 30°C; hold for a time sufficient to equilibrate the sample with the
f
furnace. Then, heat the sample to a temperature of at least A + 30°C.
f
10.5 Data Acquisition—Record the resulting curve from the heating and cooling program from A + 30°C to M – 30°C.
f f
11. Graphical Data Reduction
11.1 Draw the baselines for the cooling and heating portions of the curve as shown in Fig. 1.
11.2 Draw the tangents to the cooling and heating spikes through the inflection points as shown in Fig. 1. If a computer program
is used
...