1、Designation: F2082/F2082M 16Standard Test Method forDetermination of Transformation Temperature of Nickel-Titanium Shape Memory Alloys by Bend and Free Recovery1This standard is issued under the fixed designation F2082/F2082M; the number immediately following the designation indicates the yearof ori
2、ginal 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. Scope1.1 This test method describes a procedure for determiningthe mart
3、ensite-to-austenite transformation temperatures of ei-ther fully annealed or heat-treated nickel titanium alloys bymeasuring the deformation recovered during the thermal trans-formation.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values
4、stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith this standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its
5、 use. It is theresponsibility 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 Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and Bias inASTM Test Method
6、sE220 Test Method for Calibration of Thermocouples ByComparison TechniquesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF2005 Terminology for Nickel-Titanium Shape MemoryAlloys3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 Def
7、initionsSpecific technical terms used in this testmethod are found in Terminology F2005.3.1.2 free recoveryunconstrained motion of a shapememory alloy upon heating and transformation to austeniteafter deformation in a lower temperature phase.3.1.3 Af-95austenite finish temperature of a finished wire
8、,tube, or component measured by bend and free recovery usingthe 95 percent recoverable deformation methodology.3.1.4 Af-tanaustenite finish temperature of a finished wire,tube, or component measured by bend and free recovery usingthe tangent methodology.3.2 Abbreviations:3.2.1 LVDTlinear variable di
9、fferential transducer.3.2.2 RVDTrotary variable differential transducer.4. Summary of Test Method4.1 This test method involves cooling a test specimen to itsnominally fully martensitic phase, deforming the specimen,and heating the specimen to its fully austenitic phase. Duringheating, the motion of
10、the specimen is measured and plottedversus the specimen temperature. For a two-stagetransformation, the Rs, Rf, As, and Af, as defined in Terminol-ogy F2005, are determined using the tangent methodology. Fora single-stage transformation, the Asand Afare determinedusing the tangent methodology. Alter
11、natively, for either singleor two-stage transformation material, the Afmay be measuredusing the 95 percent recoverable deformation methodology.5. Significance and Use5.1 This test method provides a rapid, economical methodfor determination of transformation temperatures.5.2 Measurement of the specim
12、en motion closely parallelsmany shape memory applications and provides a result that isapplicable to the function of the material.5.3 This test method uses wire, tube, or strip samples; thus,it is able to provide an assessment of the product in itssemifinished form.1This test method is under the jur
13、isdiction of ASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved April 1, 2016. Published May 2016. Originallyapproved in 2001. Last previous edition approved in 2015 as F2082 15. DOI
14、:10.1520/F2082-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harb
15、or Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.4 This test method may be used on annealed samples todetermine the transformation temperatures and assure the alloyformulation, since chemical analysis is not precise enough todetermine adequately the nickel-to-titanium ratio o
16、f shapememory alloys.5.5 Transformation temperatures derived from this testmethod may differ from those derived from other methods as aresult of the effects of strain and load on the transformationtemperature.5.6 The test method is applicable to shape memory alloyswith Aftemperatures in the range of
17、 approximately 25 to6 90C.6. Apparatus6.1 LVDT, with range greater than half the mandrel diameter(see 9.2), with power supply, mounted in an appropriate fixturewith counterbalanced probe (see Fig. 1); or RVDT with rangegreater than 45, with power supply, mounted in an appropriatefixture (see Fig. 2)
18、; or a vision system; or equivalent means ofmeasuring sample displacement.6.2 Thermocouple and Indicator, with resolution of 0.1C(0.2F) or better.6.3 XY Chart Recorder, or equivalent manual or automateddata acquisition system.6.4 Hot Plate and Stirrer.6.5 Bath of Heat Transfer Fluid, for example, de
19、naturedalcohol, ethylene glycol, water, and so forth.6.6 Mandrel, for deforming the sample in the martensiticstate.6.7 Fixture, for holding the sample during recovery.6.8 Liquid Nitrogen, or dry ice.7. Sampling7.1 Test specimen can be a wire, tube, or strip with diameteror thickness in the range of
20、0.3 to 3.0 mm (0.012 to 0.12 in.).For test systems that do not contact the specimen (for example,vision system), the diameter or thickness may be less than 0.3mm.7.2 Specimens may be tested in the semifinished (heat-treated) or annealed condition. Anneal is defined in Terminol-ogy F2005.8. Calibrati
21、on8.1 The thermocouple and indicator shall be kept in acalibrated condition, traceable to the National Institute forStandards and Technology or appropriate National MetrologyInstitute that successfully participates in relevant internationalinterlaboratory comparisons.8.2 The thermocouple shall be ca
22、librated using Test MethodE220.9. Procedure9.1 For alloys that are superelastic at room temperature,cool a bath of appropriate heat transfer fluid to 55C (67F)FIG. 1 Schematic Showing Side View of Test Apparatus Using a Vertically Mounted and Counterbalanced LVDT(LVDT Power Supply, Thermocouple Indi
23、cator, and Data Acquisition System are not shown)F2082/F2082M 162or lower using liquid nitrogen, dry ice, or other suitablemethod. For alloys that are martensitic at room temperature,cool the bath to 10C (50F) or lower.9.2 Select a mandrel according to the sample diameter orthickness to give an oute
24、r fiber strain of 2 to 2.5 %. For thesestrains, mandrel diameter shall be between 39 and 49 timesspecimen diameter or thickness.9.3 Cut a test specimen long enough to wrap 90 to 180around the mandrel.9.4 Place the recovery fixture and the mandrel, along withthe test specimen, in the bath and wait a
25、minimum of 3 min forthe fixtures to equilibrate to the bath temperature.9.5 Deform the specimen in the bath by wrapping it 90 to180 around the mandrel.9.6 Place the specimen on a fixture (recovery fixture) thatholds the sample so as not to interfere with the free recovery ofthe specimen on heating.9
26、.7 Remove the mandrel from the bath. Alternatively, themandrel can be attached to the recovery fixture and left in thebath. In this case, the thermal mass of the mandrel and fixtureshall be such that the temperature of the fixture and the bath isuniform throughout the test.9.8 Set the apparatus to m
27、easure the motion of the sample.9.8.1 For an LVDT, lower the LVDT core onto the specimenas shown in Fig. 3. The weight of the LVDT core shall becounterbalanced such that the weight on the specimen is nomore than 3 g.9.8.2 For an RVDT, make sure that the needle is in contactwith the test specimen (Fi
28、g. 4). To minimize friction effects, theneedle shall be encased in a polytetrafluoroethylene (PTFE)sheath, or the needle shall be constructed from or coated withPTFE or material with equivalent friction.9.9 Place the thermocouple in the bath as close to thespecimen as is practical.9.10 Set the XY ch
29、art or data acquisition system to recordthe temperature on the either X or Y axis and sample motion onthe other axis.9.11 Stir and heat the bath on the hot plate to a temperatureabove the Af(measured according to method to be used inSection 10). Limit the heating rate to no more than 4C/minduring th
30、e recovery.9.12 Stop the test once the temperature is at least 10Cabove the Af(measured according to method to be used inSection 10), as determined by noting that the sample is straightand the displacement-versus-temperature curve has flattened.Turn off the hot plate and stop recording.10. Determina
31、tion of Transformation Temperature10.1 Determine the transformation temperatures (Rs,Rf,Asor Af) using the tangent method or determine Afusing the 95percent recoverable deformation methodology.10.2 To determine Asand Af-tan, refer to Fig. 5 and Fig. 6.The transformation may occur in one or two stage
32、s. For aone-stage transformation, the middle tangent line should beFIG. 2 Schematic Showing Top View of Test Apparatus using an RVDT(RVDT Power Supply, Thermocouple Indicator, and Data Acquisition System are not shown)F2082/F2082M 163drawn tangent to the steepest portion of the curve (see Fig. 5).In
33、 the case of a two-stage transformation, one line should bedrawn tangent to the steepest slope observed in the first stageof the transformation, and a second line should be drawntangent to the steepest slope in the second stage of thetransformation (see Fig. 6).10.3 To determine the Af-95transformat
34、ion temperature,refer to Fig. 7. Af-95is determined when the deformation is95 % recovered. Although the test may be started at lowertemperatures than 55 C, the deformation of the sample at55 C shall be considered to be its fully deformed condition(i.e., 0 % recovery). A 100 % recovery of deformation
35、 shall beconsidered to occur 10C beyond the temperature that thedisplacement-versus-temperature curve attains a constantslope.11. Report11.1 The report shall include the following information:11.1.1 Complete identification of the material tested includ-ing specification, lot number, and heat treatme
36、nt.FIG. 3 Placement of LVDT Core on Deformed Specimen, which is resting on Recovery Fixture PinsFIG. 4 Placement of Needle on Deformed Specimen, which is Clamped to the Recovery Fixture. Top View Shown with Stylus and RVDTRemoved. Note that the Recommended RVDT Axis Location is Offset from the Mandr
37、el by the Radius of the NeedleF2082/F2082M 16411.1.2 Results of the transformation measurements, reportedto the nearest 1C.12. Precision and Bias12.1 An interlaboratory study was conducted in accordancewith Practice E691 in six laboratories with two differentmaterials, with each laboratory obtaining
38、 five results for eachmaterial. There were two rounds of testing. In the first round,the test samples were cold-worked and stress-relieved; in theFIG. 5 Tangent Method: One-Stage TransformationTangent Lines and Transformation TemperaturesFIG. 6 Tangent Method: Two-Stage TransformationTangent Lines a
39、nd Transformation TemperaturesTABLE 1 Repeatability and Reproducibility for Asof Cold-Worked and Stress-Relieved MaterialMaterial As,grandmeanRepeatabilitystandarddeviationReproducibilitystandarddeviationRepeatability ReproducibilityA 29.0 1.4 3.4 4.1 9.5B 12.4 2.5 4.5 6.9 12.5F2082/F2082M 165second
40、 round, the samples were fully annealed. The details aregiven in Research Report No. F041009.312.2 The results of round one are shown in Table 1 andTable 2 for each transformation temperature (As, Af-tan). Thevalues are in degrees Celsius. The terms repeatability limit andreproducibility limit are u
41、sed as specified in Practice E177.12.3 The results of round two are shown in Table 3 andTable 4 for each transformation temperature (As,Af-tan). Thevalues are in degrees Celsius. The terms repeatability limit andreproducibility limit are used as specified in Practice E177.12.4 BiasNo measurement of
42、bias is possible with this testmethod because there is no accepted reference material ormethod.13. Keywords13.1 free recovery; nickel titanium; nitinol; shape memory;transformation temperature3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Researc
43、h Report RR:F04-1009.TABLE 2 Repeatability Limit and Reproducibility Limit for Af-tanof Cold-Worked and Stress-Relieved MaterialMaterial Af,grandmeanRepeatabilitystandarddeviationReproducibilitystandarddeviationRepeatability ReproducibilityA 11.7 1.8 4.5 4.9 12.7B 2.9 1.5 4.8 4.3 13.6TABLE 3 Repeata
44、bility Limit and Reproducibility Limit for Asof Annealed MaterialMaterial As,grandmeanRepeatabilitystandarddeviationReproducibilitystandarddeviationRepeatability ReproducibilityA 25.4 1.4 2.2 4.1 6.3B 0.2 1.9 2.7 5.3 7.7TABLE 4 Repeatability Limit and Reproducibility Limit for Af-tanof Annealed Mate
45、rialMaterial Af,grandmeanRepeatabilitystandarddeviationReproducibilitystandarddeviationRepeatability ReproducibilityA 18.6 1.7 2.4 4.6 6.8B 8.3 0.9 1.7 2.7 4.8FIG. 7 Percent Recovery Method: Af-95Transformation TemperatureF2082/F2082M 166APPENDIX(Nonmandatory Information)X1. RATIONALEX1.1 Transforma
46、tion temperature is used to characterizenickel-titanium alloys in the form of raw material, semifinishedmaterial, and finished product. In the case of raw material,transformation testing is necessary because chemical analysisis not precise enough to predict the desired shape memory andsuperelastic p
47、roperties.X1.2 This test method provides a rapid, economical meansof determining the martensitic-to-austenitic transformationtemperatures by recording the motion of the samples as theyexhibit the shape memory effect. In the case of finishedproducts, this test method often is used to determine the sh
48、apememory behavior of the product in its final application.X1.3 Transformation temperatures measured by this testmethod will differ from those measured by thermal analysis orother techniques as a result of the effects of strain and load.X1.4 A strain level of 2 to 2.5 % is selected to minimize theef
49、fect of strain on the transformation temperatures.X1.5 The heating rate is limited to minimize the thermalgradients in the bath. The heating rate may be controlledmanually or through the use of a temperature controller.X1.6 The thermal mass of the fixture inside the bath shouldbe minimized so that the fixture and the bath are uniform intemperature.X1.7 Samples larger than 3 mm in thickness or diameter canbe tested with this test method with the addition of a fixture toaid in the deformation of the sample. A vision system isrecommended
