1、Designation: E3097 17Standard Test Method forMechanical Uniaxial Constant Force Thermal Cycling ofShape Memory Alloys1This standard is issued under the fixed designation E3097; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method defines procedures for determining thetransformation temperatures, the related strains and the
3、re-sidual strain when a shape memory alloy is thermally cycledunder an applied axial stress. This test is done to provide datafor the design and selection of shape memory alloy thermoelas-tic actuators.1.2 UnitsThe values stated in SI units are to be regardedas standard. No other units of measuremen
4、t are included in thisstandard.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, health, and environmental practices and deter-mine the applicability of regu
5、latory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade O
6、rganization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE8/E8M Test Methods for Tension Testing of Metallic Ma-terialsE9 Test Methods of Compressio
7、n Testing of Metallic Mate-rials at Room TemperatureE21 Test Methods for Elevated Temperature Tension Tests ofMetallic MaterialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE74 Practice of Calibration of Force-Measuring Instrumentsfor Verifying th
8、e Force Indication of Testing MachinesE83 Practice for Verification and Classification of Exten-someter SystemsE209 Practice for Compression Tests of Metallic Materials atElevated Temperatures with Conventional or Rapid Heat-ing Rates and Strain RatesE691 Practice for Conducting an Interlaboratory S
9、tudy toDetermine the Precision of a Test MethodE1169 Practice for Conducting Ruggedness TestsE2368 Practice for Strain Controlled ThermomechanicalFatigue TestingF2004 Test Method for Transformation Temperature ofNickel-Titanium Alloys by Thermal AnalysisF2005 Terminology for Nickel-Titanium Shape Me
10、moryAlloysF2063 Specification for Wrought Nickel-Titanium ShapeMemory Alloys for Medical Devices and Surgical Im-plantsF2082 Test Method for Determination of TransformationTemperature of Nickel-Titanium Shape Memory Alloysby Bend and Free RecoveryF2516 Test Method for Tension Testing of Nickel-Titan
11、iumSuperelastic Materials2.2 Other Standards:IEEE/ASTM SI 10 American National Standard for MetricPractice2ASQ C1 general Requirements for a Quality program3ISO 9001 Quality Management SystemsRequirements43. Terminology3.1 Specific technical terms used in this test method arefound in Terminology F20
12、05.3.2 Definitions:1This test method is under the jurisdiction of ASTM Committee E08 on Fatigueand Fracture and is the direct responsibility of Subcommittee E08.05 on CyclicDeformation and Fatigue Crack Formation.Current edition approved Nov. 1, 2017. Published March 2018. DOI: 10.1520/E3097172For r
13、eferenced 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.3Available from American National Standards Institute (ANSI), 25 W.
14、 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4Available from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, http:/www.iso.org.Copyright ASTM International, 100 Barr Harbor Drive,
15、PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued
16、 by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.1 actuation strain (eact)The full strain recoveryobtained when heating from LCT to UCT at a specified stress.It includes the thermal expansions of martensite and austeniteas well the phase transformation strain. eact5e
17、LCT2eUCT3.2.2 austenite50% (A50)Temperature at which the trans-formation from martensite to austenite is 50% completed. A505As1 Af!2 .3.2.3 austenite finish strain (eAf)Strain at the austenitefinish temperature.3.2.4 austenite start strain (eAs)Strain at the austenite starttemperature.3.2.5 hysteres
18、is width (HWIDTH)Width of the thermalhysteresis curve in degrees centigrade. Distance on the tem-perature axis between a vertical line drawn through the A50point and a vertical line drawn through the M50point.3.2.6 initial strain (e0)Specimen strain at UCT afternormalizing (see 11.1) and prior to lo
19、ading the specimen.3.2.7 lower cycle temperature (LCT)Minimum tempera-ture of the thermal cycle. It is selected to be 10 to 30C lowerthan Mfdetermined by a DSC test per Test Method F2004.However, the DSC test shall be done on the sample material inthe same condition as the UCFTC test material.3.2.8
20、martensite 50% (M50)Temperature at which thetransformation from austenite to martensite is 50% completed.M505Ms1 Mf!2.3.2.9 initial loading strain (ei)Initial specimen strain afternormalization and before cooling when loaded at the UCT.3.2.10 residual strain (eres)The final strain at the uppercycle
21、temperature minus the initial strain at the upper cycletemperature. eres5eUCT2ei3.2.11 strain at the lower cycle temperature (eLCT)Specimen strain at the LCT after cooling from the UCT to theLCT under the specified stress. (See Fig. 1.)3.2.12 strain at the upper cycle temperature (eUCT)Specimen stra
22、in at the UCT after cooling to the LCT andheating to the UCT at the specified stress. (See Fig. 1.)3.2.13 thermal transformation span (TSPAN)Thermaltransformation span in degrees centigrade at a specified stress.Distance on the temperature axis between a vertical line drawnthrough the Af point and a
23、 vertical line drawn through the Mfpoint. TSPAN5Af2Mf.3.2.14 transformation strain (et)The strain recovery dueto the austenitic transformation obtained when heating at aspecified stress. eT5eAs2eAf3.2.15 upper cycle temperature (UCT)The maximumtemperature of the thermal cycle. It is selected to be h
24、igher thanthe Afdetermined by a DSC test per Test Method F2004. Forexample, a temperature between 10 to 100 C above Afmay beselected in consideration of the stress applied to the specimen.FIG. 1 Typical Constant Force Thermal Cycle and Test Methods TermsE3097 172The DSC test shall be done on the sam
25、ple material in the samecondition as the UCFTC test material.3.3 Abbreviations:3.3.1 UCFTCUniaxial Constant Force Thermal Cycling3.4 See also Terminology E6.4. Summary of Test Method4.1 Using a conventional uniaxial tension or compressiontesting apparatus (or a dead weight loading system) with atemp
26、erature control chamber (or other system for heating andcooling at a controlled rate) the material is heated to the UCT,above the austenite finish (Af) temperature, loaded to a speci-fied stress, then cooled to the LCT, a temperature below themartensite finish (Mf) temperature, and then heated to th
27、eUCT5. Significance and Use5.1 Constant force thermal cycling tests determine the effectof stress on the transformation temperatures, recovered strainand residual strain of a shape memory alloy. The tests may befor one thermal cycle but may involve repeated thermal cycleswith the number of cycles in
28、creasing by orders of magnitude10 until the response of the material to thermal cycling nolonger changes.6. Interferences6.1 The initial condition of the test specimen can signifi-cantly impact test results.NOTE 1Care should be taken to assure the material is free ofunintended residual stresses from
29、 fabrication, processing, or handling.Cutting and grinding can cause cold work which affects the transformationtemperatures. Oxidation during heat treatment can change the thermalproperties of the specimen and affect the temperature uniformity. Sucheffects are magnified by specimens with smaller gau
30、ge diameters.6.2 When testing wire, make sure that the gripping mecha-nism does not cause errors in strain measurement, for exampleslipping in the grips.6.3 For tension and compression testing the extensometerdesign and size shall be chosen so that the extensometermeasures all deformation within the
31、 reduced gage length of thesample.6.4 Complete thermal transformation is required for accu-rate results. The materials martensite finish and austenitefinish temperatures may be estimated prior to the test byDifferential Scanning Calorimetry (Test Method F2004), orBend and Free Recovery (Test Method
32、F2082).6.5 Make sure that the heating and cooling system maintainsa uniform specimen temperature within 6 3C, along thespecimen length, over the gauge section. Temperature gradi-ents in the specimen will affect the apparent transformationtemperatures and strains. See 10.1 for details on temperaturem
33、easurement.6.6 The heating and cooling rate for the test shall beconsistent with the sample thickness so that the test section ofthe specimen is at a uniform temperature within 6 3C,transverse to the specimen length, over the gauge section. See10.1 for details on temperature measurement.NOTE 2Requir
34、ements specified in interferences 6.5 and 6.6 may beachieved by selecting hold times at the UCT and LCT to insure thespecimen and temperature control system are fully equilibrated beforestarting/continuing the thermal cycle.6.7 Make sure the specimen is fully austenitic at the uppercycle temperature
35、 (UCT) for all stress levels to be tested.However, make sure that the UCT is not so high as to causestrain aging of the specimen. This is shown graphically in Fig.2.6.8 Make sure that the specimen is fully martensitic at thelower cycle temperature (LCT).6.9 The output signal of a mechanical extensom
36、eter maychange as a function of temperature. See Practice E83, Appen-dix X2. A thermal compensation routine shall be developed tocompensate for the changes in the output signal. See 9.2.7. Apparatus7.1 The tension apparatus is as described in Test MethodsE8/E8M.7.2 The compression testing machine be
37、aring blocks andstrain transducer shall be as described in Test Methods E9 orPractice E209.7.3 The heating and cooling apparatus and the temperaturemeasuring apparatus shall be as described in E21 for tensiontesting and Practice E209 for compression testing.7.4 The test apparatus shall be capable of
38、 controlling testspecimen temperature in air between a minimum temperatureof Mf- 30C and a maximum temperature of Af+ 100C witha temperature uniformity of 6 3C in the axial and transversedirection, over the gauge section. See 10.1 for details ontemperature measurement.8. Sampling, Test Specimens, an
39、d Test Units8.1 The number and location of samples from each lot ofmaterial shall be agreed upon between the customer and thesupplier.8.2 Tensile specimens are as described in Test MethodsE8/E8M for different product forms except that the gage lengthneeds to be a minimum of one (1) times the diamete
40、r.8.3 For wires, strain may be measured from displacementbetween the grips.8.4 Compression specimens are described in Test MethodsE9 and Practice E209.9. Calibration and Standardization9.1 The tension or compression testing system shall becalibrated and verified according to Practices E4.9.2 An exte
41、nsometer system shall be verified according toPractice E83 Class B-2. The strain signal of a mechanicalextensometer will change as a function of temperature. SeePractice E83, Appendix X2. To compensate for a thermallyinduced shift in an extensometer a zero-force thermal straincompensation routine sh
42、all be used. The extensometer isattached to a specimen having a known coefficient of thermalexpansion. For example, NIST Standard Reference MaterialE3097 173FIG. 2 Effects of Force and Upper Cycle Temperature on test results.A) UCT sufficient for complete Austenitic transformation.B) UCT not suffici
43、ent for complete Austenitic transformation.E3097 174731L1, borosilicate glass, has been shown to be a suitablematerial. Using the same thermal cycle profile as the plannedtest, including the UCT, LCT, and the heating and coolingrates, the extensometer output signal is recorded over acomplete thermal
44、 cycle. The thermal effect on the offset isdetermined by the difference between the extensometer outputand the known thermal expansion. The determined thermalresponse shall then be used within the tests thermal cycle toprovide strain compensation values.10. Heating and Cooling10.1 Measurement and co
45、ntrol of temperature, temperaturegradients and heating/cooling rates shall be employed perPractice E2368, Section 7.4. In this instance, Tmax= UCT anddue to the hysteretic behavior of SMA, Practice E2368, Section7.4.5 should be disregarded. The maximum allowable gradientshall be 63C in both the axia
46、l and transverse direction, overthe gauge section.11. Procedure11.1 Normalizing:11.1.1 The specimen shall be mounted in a tensile/compression load system at room temperature with the entiretest system equilibrated at room temperature. The load is set toa minimum force not to exceed a corresponding s
47、tress of7 MPa (in accordance Test Method F2516).11.1.2 The specimen is heated to the UCT, cooled to theLCT and then reheated and held at the UCT. The heating andcooling rates for normalizing are not restricted to a specific ratebut shall be sufficient to ensure temperature equilibration at theUCT an
48、d LCT, as specified in 10.1.11.2 After normalizing, hold the temperature for a timesufficient to equilibrate the temperature and strain, load thespecimen to the selected stress level. The stress level shall bedefined by the customer or by the test operator based on auniaxial test of the material in
49、the austenitic condition. See TestMethod F2516.11.3 Cool the sample to the LCT, hold the temperature for atime sufficient to equilibrate the temperature and strain. Heatthe sample to the UCT. Hold the temperature for a timesufficient to equilibrate the temperature and strain in accor-dance with 10.1. Record the sample strain (displacement) as afunction of temperature during the cooling and heating cycles.12. Calculation or Interpretation of Results12.1 Plot the strain verses temperature data as shown in Fig.1.12.2 Graphically determine As, Af,
