1、Designation: E3098 17Standard Test Method forMechanical Uniaxial Pre-strain and Thermal Free Recoveryof Shape Memory Alloys1This standard is issued under the fixed designation E3098; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、the year 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 describes the heating and cooling aShape MemoryAlloy (SMA) specimen through transformatio
3、nafter uniaxial deformation to determine residual strain afterloading and unloading, recovered strain on heating, totalunrecovered strain upon cooling, and transformation tempera-tures.1.2 UnitsThe values stated in SI units are to be regardedas standard. No other units of measurement are included in
4、 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 regulatory limitation
5、s 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 Organization Techn
6、icalBarriers 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 Compression Testing of Meta
7、llic 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 the Force Indicatio
8、n of Testing MachinesE83 Practice for Verification and Classification of Exten-someter SystemsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE209 Practice for Compression Tests of Metallic Materials atElevated Temperatures with Conventional or Rapid Heat-ing Rates and Strai
9、n RatesE691 Practice for Conducting an Interlaboratory Study 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 Therma
10、l AnalysisF2005 Terminology for Nickel-Titanium Shape MemoryAlloysF2063 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 Recov
11、eryF2516 Test Method for Tension Testing of Nickel-TitaniumSuperelastic 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 DefinitionsSpecific t
12、echnical terms used in this testmethod are found in Terminology F2005:1This 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, 201
13、7. Published March 2018. DOI: 10.1520/E3098172For 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.3Available from
14、American National Standards Institute (ANSI), 25 W. 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.Co
15、pyright ASTM International, 100 Barr Harbor Drive, 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 Interna
16、tional Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2 austenite finish strain (eAf)Strain at the austenite finishtemperature.3.3 austenite start strain (eAs)Strain at the austenite starttemperature.3.4 initial Strain (e0)
17、Specimen strain at LCT after nor-malizing (see 11.1) and prior to pre-straining the specimen.3.5 lower cycle temperature (LCT)LCT is the minimumtemperature of the thermal cycle. It is selected to be 10 to 30Clower than Mfdetermined by a DSC test in accordance withTest Method F2004. However, the DSC
18、test shall be done onthe sample material in the same condition as the UPFR testmaterial.3.6 maximum loading strain (ei)Maximum specimenstrain during pre-straining at the LCT.3.7 recovery strain (erec)Is the amount of residual strainthat is recovered in the specimen after heating to the UCT andcoolin
19、g to the LCT following pre-straining, it is equal to theunloaded strain (eu) minus strain at lower cycle temperature(eLCT) after cooling from the UCT.3.8 strain at lower cycle temperature (eLCT)Specimenstrain at the LCT after pre-straining and unloading at the LCTand heating to the UCT and cooling t
20、o LCT.3.9 strain at upper cycle temperature (eUCT)Specimenstrain at the UCT after pre-straining and unloading at the LCTand heating to the UCT.3.10 stress (S)Stress is defined as the ratio of force to thespecimen original cross sectional area.3.11 transformation strain (et)The strain recovery due to
21、the austenitic transformation obtained when heating at aspecified stress. eT5eAs2eAf3.12 two way strain (eTW)Specimen strain at the LCT aftercooling from the UCT minus the strain at the UCT. This is thestrain induced in the shape memory alloy specimen when it iscooled from UCT to LCT with an applied
22、 tensile stress of7 MPa or less. eTW5eLCT2eUCT3.13 unloaded strain (eu)Specimen strain at LCT afterpre-straining and then unloading, but prior to heating.3.14 upper cycle temperature (UCT)UCT is the maximumtemperature of the thermal cycle. It is selected to be higher thanthe Afdetermined by a DSC te
23、st in accordance with TestMethod F2004. For example, a temperature between 10 to100 C above Afmay be selected in consideration of the strainapplied to the specimen. The DSC test shall be done on thesample material in the same condition as the UPFR testmaterial.3.15 Abbreviations:3.15.1 UPFRUniaxial
24、Pre-strain and Thermal Free Re-covery3.16 See also E4: General Terminology4. Summary of Test Method4.1 This test method involves cooling a test specimen to itsfully martensitic state, deforming the specimen to a definedstrain under uniaxial loading, removing the force, heating thespecimen to its ful
25、ly austenitic phase, and then cooling thespecimen to its fully martensite phase. During heating andcooling the extension or contraction of the specimen ismeasured and plotted versus the specimen temperature.5. Significance and Use5.1 This test method is used to measure a specimensmaterial and shape
26、memory effect properties in response to auniaxial deformation and then cycling through a full thermaltransformation to recover all or a portion of the deformation. Amaterials martensite stiffness, martensite residual strain, aus-tenite recovered strain, and unrecovered strain (or plasticdeformation)
27、 after thermal cycling is determined.5.2 Measurement of the specimens motion closely parallelsmany shape memory applications and provides a result that isapplicable to the function of the material.5.3 This test method may be used for, but is not limited to,wire, round tube, or strip samples. It is a
28、ble to provide anassessment of the product in its semi-finished form.5.4 This test method provides a simple method for deter-mining transformation temperatures by heating and coolingspecimens through their full thermal transformation afteruniaxial pre-straining in the martensite state.5.5 This test
29、method can be used on trained and processedmaterial in a semi-finished form to measure Two Way ShapeMemory Effect by comparing the strain in the austenite stateand martensite states with no applied stress.5.6 This test method is useful for quality control, specifica-tion acceptance, and research.5.7
30、 Transformation temperatures derived from this testmethod may not agree with those obtained by other testmethods due to the effects of strain and stress on the transfor-mation.5.8 Components such as springs or other semi-finished partscan be tested using this method as agreed upon by the customerand
31、 supplier. Units of stress and strain can be replaced withforce and displacement.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 fabrication, processing
32、, 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 gauge diameters.6.2 Complet
33、e 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 F2082).6.3 Make sure that the heating and coo
34、ling 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 transformationE3098 172temperatures and strains. Please see 10.1 for details on tem-perature measurement.6.4 The heating
35、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 additional details on temperature measurement.NOTE 2Interferences 6.3 and
36、6.4 may be achieved by selecting holdtimes at the UCT and LCT to insure the specimen and temperature controlsystem are fully equilibrated before starting/continuing the thermal cycle.6.5 Transformation temperatures will vary with the pre-strain applied to the specimen and also vary from alloy to all
37、oysubjected to the same strain. For unfamiliar alloys it isrecommended that a range of pre-strains be tested to assess theeffect of the maximum strain prior to any extensive testprogram. For example, plateau strain under uniaxial loadingcan be used to establish initial test conditions (Test MethodF2
38、516).6.6 In the absence of a specified pre-strain limit, thespecimen pre-strain can be a minimum of the 1% yield offsetas defined by the offset method described in Test MethodsE8/E8M.6.7 The output signal of a mechanical extensometer maychange as a function of temperature. See Practice E83, Appen-di
39、x 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 bearing blocks andstrain transducer shall be as described in Test Methods
40、 E9 orPractice E209.7.3 The heating and cooling apparatus and the temperaturemeasuring apparatus shall be as described in Test Method E21for high temperature tension testing and Practice E209 forcompression testing.7.4 The test apparatus shall be capable of controlling testspecimen temperature in ai
41、r between a minimum temperatureof Mf-30C and a maximum temperature of Af+100C with atemperature uniformity of 6 3C in the axial and transversedirection overt the gauge section. See 10.1 for details ontemperature measurement.8. Sampling, Test Specimens, and Test Units8.1 The number and location of sa
42、mples 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 diameter.8.3 For wires, strain may be measured from
43、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 extensometer system shall be verified according t
44、oPractice 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 shall be used. The extensometer isattached to a
45、 specimen having a known coefficient of thermalexpansion. For example, NIST Standard Reference Material731L1, 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 extensomet
46、er output signal is recorded over acomplete thermal 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 va
47、lues.10. Heating and Cooling10.1 Measurement and control of temperature, temperaturegradients and heating/cooling rates shall be employed inaccordance with Practice E2368, Section 7.4. In this instance,Tmax= UCT and due to the hysteretic behavior of SMA,Practice E2368, Section 7.4.5 should be disreg
48、arded. Themaximum allowable gradient shall be 63C in both the axialand transverse direction, over the 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.
49、 The load is set toa minimum force not to exceed 7 MPa (in accordance with TestMethod F2516).11.1.2 The specimen is heated to the UCT, cooled to theLCT and held at the temperature and stress for a time sufficientto equilibrate the temperature and strain. The heating andcooling rates for normalizing are not restricted to a specific ratebut shall be sufficient to ensure temperature equilibration at theUCT and LCT, as specified in 10.1.11.2 Adjust the specimen temperature to Mf-10C or less, orthe temperature specified in the test plan or product specif
