1、Designation: F 2082 06Standard Test Method forDetermination of Transformation Temperature of Nickel-Titanium Shape Memory Alloys by Bend and Free Recovery1This standard is issued under the fixed designation F 2082; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a procedure for determiningthe martensite-to-a
3、ustenite 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 in SI units are to be regarded as the standard.The values given in inch-pound units are provided for infor-mat
4、ion only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its 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. Ref
5、erenced Documents2.1 ASTM Standards:2E 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 220 Test Method for Calibration of Thermocouples ByComparison TechniquesE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF 2005 Terminology
6、 for Nickel-Titanium Shape MemoryAlloys3. Terminology3.1 DefinitionsSpecific technical terms used in this testmethod are found in Terminology F 2005.3.2 free recoveryunconstrained motion of a shapememory alloy upon heating and transformation to austeniteafter deformation in a lower temperature phase
7、.3.3 Abbreviations:3.3.1 LVDTlinear variable differential transducer.3.3.2 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
8、austenitic phase. Duringheating, the motion of the specimen is measured and plottedversus the specimen temperature. For a two-stage transforma-tion, the Rs, Rf, As, and Af, as defined in Terminology F 2005,are determined. For a single-stage transformation, the Asand Afare determined.5. Significance
9、and Use5.1 This test method provides a rapid, economical methodfor determination of transformation temperatures.5.2 Measurement of the specimen motion closely parallelsmany shape memory applications and provides a result that isapplicable to the function of the material.5.3 This test method uses wir
10、e, tube, or strip samples; thus,it is able to provide an assessment of the product in itssemifinished form.5.4 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 adequ
11、ately the nickel-to-titanium ratio of shapememory alloys.1This test method is under the jurisdiction 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 Aug. 15, 2006. Published Au
12、gust 2006. Originallyapproved in 2001. Last previous edition approved in 2003 as F 2082 03.2For 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 Su
13、mmary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.5 Transformation temperatures derived from this testmethod may differ from those derived from other methods as aresult of effects of strain and load on t
14、he transformationtemperature.5.6 The test method is applicable to shape memory alloyswith Aftemperatures in the range of approximately 25 to+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
15、probe (see Fig. 1); or RVDT with rangegreater than 45, with power supply, mounted in an appropriatefixture (see Fig. 2); or 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
16、manual or automateddata acquisition system.6.4 Hot Plate and Stirrer.6.5 Bath of Heat Transfer Fluid, for example, denaturedalcohol, 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 Nitro
17、gen, or dry ice.7. Sampling7.1 Test specimen can be a wire, tube, or strip with diameteror thickness in the range of 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
18、tested in the semifinished (heat-treated) or annealed condition. Anneal is defined in Terminol-ogy F 2005.8. Calibration8.1 The thermocouple and indicator shall be kept in acalibrated condition, traceable to the National Institute forStandards and Technology or appropriate National MetrologyInstitut
19、e that successfully participates in relevant internationalinterlaboratory comparisons.8.2 The thermocouple shall be calibrated using Test MethodE 220.9. Procedure9.1 For alloys that are superelastic at room temperature,cool a bath of appropriate heat transfer fluid to 55C (67F)or lower using liquid
20、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 outer fiber strain of 2 to 2.5 %. For thesestrains, mandrel diameter shall be between 39 an
21、d 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 minimum of 3 min forthe fixtures to equilibrate to the bath temperature.FIG. 1 Schemati
22、c Showing Side View of Test Apparatus Using a Vertically Mounted and Counterbalanced LVDT (LVDT Power Supply,Thermocouple Indicator, and Data Acquisition System Are Not Shown)F20820629.5 Deform the specimen in the bath by wrapping it 90 to180 around the mandrel.9.6 Place the specimen on a fixture (r
23、ecovery fixture) thatholds the sample so as not to interfere with the free recovery ofthe specimen on heating.9.7 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 fixturemust be
24、such that the temperature of the fixture and the bath isuniform throughout the test.9.8 Set the device to measure 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 must becounterbalanced such that the weight on the specim
25、en is nomore than 3 g.9.8.2 For an RVDT, make sure the needle is in contact withthe test specimen (Fig. 4). To minimize friction effects, theneedle shall be encased in a PTFE sheath, or the needle shall beconstructed from or coated with PTFE or material withequivalent friction.9.9 Place the thermoco
26、uple in the bath as close to thespecimen as is practical.9.10 Set the XY chart 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. Limit the heating rate to no more
27、 than 4C/minduring the recovery.9.12 Stop the test once the temperature is at least 10Cabove the Af, as determined by noting that the sample isstraight and the displacement versus temperature curve hasflattened. Turn off the hot plate and stop recording.10. Determination of Transformation Temperatur
28、e10.1 Determine the transformation temperatures accordingto Fig. 5 or Fig. 6. The transformation may occur in one or twostages. For a one-stage transformation, the middle tangent lineFIG. 2 Schematic Showing Top View of Test Apparatus Using an RVDT (RVDT Power Supply, Thermocouple Indicator, and Dat
29、aAcquisition System Are Not Shown)FIG. 3 Placement of LVDT Core on Deformed Specimen, Which IsResting on Recovery Fixture PinsF2082063should be drawn tangent to the steepest portion of the curve(see Fig. 5). In the case of a two-stage transformation, one lineshould be drawn tangent to the steepest s
30、lope observed in thefirst stage of the transformation, and a second line should bedrawn tangent to the steepest slope in the second stage of thetransformation (see Fig. 6).11. Report11.1 The report shall include the following information:11.1.1 Complete identification of the material tested includ-i
31、ng specification, lot number, and heat treatment.11.1.2 Results of the transformation measurements, reportedto the nearest 1C.12. Precision and Bias12.1 An interlaboratory study was conducted in accordancewith Practice E 691 in six laboratories with two differentmaterials, with each laboratory obtai
32、ning five results for eachmaterial. There were two rounds of testing. In the first round,the test samples were cold-worked and stress-relieved; in thesecond 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
33、 andTable 2 for each transformation temperature (As,Af). Thevalues are in degrees Celcius. The terms repeatability limit andreproducibility limit are used as specified in Practice E 177.12.3 The results of round two are shown in Table 3 andTable 4 for each transformation temperature (As,Af). Thevalu
34、es are in degrees Celcius. The terms repeatability limit andreproducibility limit are used as specified in Practice E 177.12.4 BiasNo measurement of bias is possible with thistest method because there is no accepted reference material ormethod.13. Keywords13.1 free recovery; nickel titanium; nitinol
35、; shape memory;transformation temperature3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: F041009.FIG. 4 Placement of Needle on Deformed Specimen, Which IsClamped to the Recovery Fixture. Top View Shown with Stylusand RVDT Remov
36、ed. Note the Recommended RVDT AxisLocation Is Offset from the Mandrel by the Radius of the NeedleF2082064FIG. 5 One-Stage TransformationTangent Lines and Transformation TemperaturesFIG. 6 Two-Stage TransformationTangent Lines and Transformation TemperaturesF2082065APPENDIX(Nonmandatory Information)X
37、1. RATIONALEX1.1 Transformation 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 sha
38、pe memory andsuperelastic properties.X1.2 This test method provides a rapid, economic means ofdetermining the martensitic-to-austenitic transformation tem-peratures by recording the motion of the samples as it exhibitsthe shape memory effect. In the case of finished products, thistest method often i
39、s used to determine the shape memorybehavior 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 Astrain level of 2 to 2.5 % is s
40、elected to minimize theeffect 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 sho
41、uldbe minimized so that the fixture and the bath are uniform.X1.7 Samples larger than 3 mm in thickness or diametercan be tested with this test method with the addition of a fixtureto aid in the deformation of the sample. A vision system isrecommended for samples less than 0.3 mm, because friction i
42、nan RVDT or LVDT system may create a stress in the specimen.TABLE 1 Repeatability and Reproducibility for Asof Cold-Worked and Stress-Relieved MaterialMaterial As,grand meanRepeatabilitystandarddeviationReproducibilitystandarddeviationRepeatability ReproducibilityA 29.0 1.4 3.4 4.1 9.5B 12.4 2.5 4.5
43、 6.9 12.5TABLE 2 Repeatability and Reproducibility for Afof Cold-Workedand Stress-Relieved MaterialMaterial Af,grand meanRepeatabilitystandarddeviationReproducibilitystandarddeviationRepeatability ReproducibilityA 11.7 1.8 4.5 4.9 12.7B 2.9 1.5 4.8 4.3 13.6TABLE 3 Repeatability and Reproducibility f
44、or Asof AnnealedMaterialMaterial As,grand meanRepeatabilitystandarddeviationReproducibilitystandarddeviationRepeatability ReproducibilityA 25.4 1.4 2.2 4.1 6.3B 0.2 1.9 2.7 5.3 7.7TABLE 4 Repeatability and Reproducibility for Afof AnnealedMaterialMaterial Af,grand meanRepeatabilitystandarddeviationR
45、eproducibilitystandarddeviationRepeatability ReproducibilityA 18.6 1.7 2.4 4.6 6.8B 8.3 0.9 1.7 2.7 4.8F2082066ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advise
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48、ou feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).F2082067
