1、Designation: F2516 072F2516 14Standard Test Method forTension Testing of Nickel-Titanium Superelastic Materials1This standard is issued under the fixed designation F2516; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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 NOTEReferenced Documents were updated editorially in April 2008.2 NOTEA heading in Table 1 was editorially corrected in Septembe
3、r 2008.1. Scope1.1 This test method covers the tension testing of superelastic nickel-titanium (nitinol) materials, specifically the methods offordetermination of upper plateau strength, lower plateau strength, residual elongation, tensile strength, and elongation.1.2 The values stated in SI units a
4、re 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 responsibilityof the user of this standard to establish appropriate safety and health practi
5、ces and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E6 Terminology Relating to Methods of Mechanical TestingE8 Test Methods for Tension Testing of Metallic MaterialsE83 Practice for Verification and Classification of Extensometer Syste
6、msE111 Test Method for Youngs Modulus, Tangent Modulus, and Chord ModulusE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE1876 Test Method for Dynamic Youngs Modulus, Shear Modu
7、lus, and Poissons Ratio by Impulse Excitation of VibrationF2005 Terminology for Nickel-Titanium Shape Memory Alloys3. Terminology3.1 The definitions of terms relating to tension testing appearing in Terminology E6 and the terms relating to nickel-titaniumshape memory alloys appearing in Terminology
8、F2005 shall be considered as applying to the terms used in this test method.Additional terms being defined are as follows (see Fig. 1):3.2 Definitions:3.2.1 lower plateau strength (LPS)the stress at 2.5 % strain during unloading of the sample, after loading to 6 % strain.3.2.2 residual elongation, E
9、lr% the difference between the strain at a stress of 7.0 MPa during unloading and the strain ata stress of 7.0 MPa during loading.3.2.3 uniform elongation, Elu%the elongation determined at the maximum force sustained by the test piece just prior tonecking, or fracture, or both.3.2.4 upper plateau st
10、rength (UPS)the stress at 3 % strain during loading of the sample.4. Summary of Test Method4.1 Using conventional tensile testing apparatus, the material is pulled to 6 % strain, then unloaded to less than 7 MPa, thenpulled to failure.1 This test method is under the jurisdiction of ASTM Committee F0
11、4 on Medical and Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Dec. 1, 2007Oct. 1, 2014. Published January 2008February 2015. Originally approved in 2005. Last previous edition approved in 20062007 asF2516 06.F
12、2516 072. DOI: 10.1520/F2516-07E02.10.1520/F2516-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This docu
13、ment 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. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as
14、appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 Tension tests provide informat
15、ion on the strength and ductility of materials under uniaxial tensile stresses.5.2 Tension tests, as described in this test method, also provide information on the superelasticity, as defined in TerminologyF2005, of the material at the test temperature.6. Apparatus6.1 Apparatus is as described in Te
16、st Methods E8.7. Test Specimen7.1 Test specimens are as described in Test Methods E8.8. Procedure8.1 Procedure shall be per Test Methods E8 with the following additions:8.1.1 Unless otherwise specified, the temperature of the test shall be 22.0C. Tolerance shall be 62.0C.22.0 6 2.0C. It isrecommende
17、d that the material be tested at a temperature that is a minimum of 5C above the austenitic finish transformationtemperature (Af) in order to prevent testing of a partially transformed material.8.1.2 Free-running The free-running crosshead speed shall be limited per Table 1.8.1.3 The test shall cons
18、ist of zeroing the force transducer, gripping the specimen, pulling the specimen to 6 % strain, reversingthe motion to unload the specimen to less than 7 MPa, and then pulling the specimen to failure.8.1.4 For materials with diameter greater than 0.2 mm, strain shall be determined by use of a calibr
19、ated extensometer of classC or better (see Practice E83). For materials with diameter less than or equal to 0.2 mm, strain may be determined by use of anextensometer or by crosshead motion. When using crosshead motion to calculate strain, the length between the grips must be 150mm.FIG. 1 Terms Illus
20、trated on Typical Stress-Strain Diagram of Superelastic NitinolTABLE 1 Crosshead Speed Limitsd, diameter orthickness (mm)AMaximum crosshead speed in mm/min permmmm of initial length of reduced section (orinitial distance between grips for specimens nothaving reduced sections)First Cycle(load to 6 %
21、strainand unload)Second Cycle(load to failure)d # 0.2 0.08 0.80.2 2.5 0.01 0.1A For tubing, use d that gives equivalent surface area to diameter ratio; for roundtubing, d = (outer diameter) (inner diameter). Editorially corrected.F2516 142NOTE 1It is recommended that strain be measured using extenso
22、meter versus crosshead displacement as this will result in a more accuratemeasurement of strain.8.1.4.1 When using a clip-on extensometer with small diameter small-diameter wire, care must be taken not to bend or distortthe wire when attaching the extensometer.8.1.5 Upper plateau strength shall be d
23、etermined as the value of the stress at a strain of 3.0 % during the initial loading of thespecimen.8.1.6 Lower plateau strength shall be determined as the value of the stress at a strain of 2.5 % during the unloading of thespecimen.8.1.7 Residual elongation shall be determined by the difference bet
24、ween the strain at a stress of 7.0 MPa during unloading andthe strain at a stress of 7.0 MPa during loading.8.1.8 The uniform elongation shall be determined by elongation when the maximum force is reached just prior to necking orfracture, or both.9. Report9.1 The report shall include the following i
25、nformation, unless otherwise specified:9.1.1 Material and sample identification,9.1.2 Specimen type,9.1.3 Upper plateau strength,9.1.4 Lower plateau strength,9.1.5 Residual elongation,9.1.6 Tensile strength,9.1.7 Uniform elongation,9.1.8 Test temperature,9.1.9 Strain determination method (extensomet
26、er or crosshead),9.1.10 Crosshead speed, and9.1.11 Gage length (length of reduced section or distance between grips for specimens not having reduced sections).10. Precision and Bias310.1 An interlaboratory study was conducted in accordance with Practice E691 using three different diameters of supere
27、lasticwire. For wire diameters of 0.2 and 0.5 mm, eleven laboratories participated in the study with each laboratory obtaining threeresults for each diameter. For the 2.5 mm diameter wire, eight laboratories participated in the study with each laboratory obtainingthree results. The details are given
28、 in ASTM Research Report RR:F04-1010.310.2 The results are summarized in Tables 2-6 for each tensile parameter. The terms repeatability limit and reproducibility limitare used as specified in Practice E177.10.3 No measurement of bias is possible with this test method since there is presently no acce
29、pted reference material.11. Keywords11.1 lower plateau strength; nickel titanium; nitinol; residual elongation; shape memory; superelasticity; upper plateau strength3 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:F04-1010.TABL
30、E 2 Precision of Upper Plateau Strength (MPa)Diameter (mm) Grand Mean RepeatabilityStandard DeviationReproducibilityStandard DeviationRepeatabilityLimitReproducibilityLimit0.2 499 13 55 36 1540.5 492 11 35 30 982.5 500 13 25 35 71F2516 143APPENDIXES(Nonmandatory Information)X1. RATIONALEX1.1 During
31、tensile testing of superelastic nitinol material, heat is given off during the austenite-to-martensite transformation.Strain rate is limited to allow the heat to transfer out of the specimen. Otherwise the increase in specimen temperature willinfluence the stress-strain response.4X1.2 Measurement of
32、 modulus of elasticity requires very precise measurements beyond the scope of this standard. Test MethodsE111 and E1876 address determination of modulus of elasticity. For superelastic nitinol, the dynamic method (Test Method E1876)is preferred. Note that the modulus of elasticity exhibits large var
33、iation with the martensitic transformation.5X1.3 Due to experimental problems associated with the establishment of the origin of the stress-strain curve, such as mechanicalbacklash, initial grip alignment, and specimen curvature, residual elongation may be negative at zero force. In addition, forcet
34、ransducers are typically not calibrated at zero force. For these reasons, the residual elongation is measured while there is a smallstress of 7 MPa on the sample.X1.4 Use of crosshead motion to calculate strain is allowed for small wires due to the possibility of distorting the wire with clip-ontype
35、 extensometers. In this case, a minimum length between grips is specified to minimize elongation errors due to deflection ofthe testing equipment. Another alternative is to use a non-contacting video extensometer.4 Shaw, J. A. and Kyriakides, S., “On the Nucleation and Propagation of Phase Transform
36、ation Fronts in a NiTi Alloy”, Acta Mater, Vol 45, No. 2, 1997, pp. 683700.5 Spinner, S. and Rozner, A. G., “Elastic Properties of NiTi as a Function of Temperature”, The Journal of Acoustical Society of America, Vol. 40, No. 5, 1966, pp.10091015.TABLE 3 Precision of Lower Plateau Strength (MPa)Diam
37、eter (mm) Grand Mean RepeatabilityStandard DeviationReproducibilityStandard DeviationRepeatabilityLimitReproducibilityLimit0.2 196 10 35 27 970.5 146 9 27 26 752.5 138 13 19 36 52TABLE 4 Precision of Residual Elongation (%)Diameter (mm) Grand Mean RepeatabilityStandard DeviationReproducibilityStanda
38、rd DeviationRepeatabilityLimitReproducibilityLimit0.2 0.11 0.09 0.13 0.24 0.360.5 0.07 0.03 0.04 0.09 0.102.5 0.11 0.05 0.12 0.13 0.33TABLE 5 Precision of Ultimate Tensile Strength (%)Diameter (mm) Grand Mean RepeatabilityStandard DeviationReproducibilityStandard DeviationRepeatabilityLimitReproduci
39、bilityLimit0.2 1459 45 135 125 3770.5 1325 23 43 65 1202.5 1268 15 15 42 41TABLE 6 Precision of Uniform Elongation (%)Diameter (mm) Grand Mean RepeatabilityStandard DeviationReproducibilityStandard DeviationRepeatabilityLimitReproducibilityLimit0.2 11.5 0.7 1.2 2.0 3.50.5 12.4 0.4 1.0 1.3 2.82.5 13.
40、3 0.6 0.7 1.8 1.9F2516 144X2. INTERLABORATORY TEST RESULTSX2.1 The details of the interlaboratory study are given in ASTM Research Report F041010. The data used to generate theprecision statistics are charted below in Figs. X2.1-X2.5.FIG. X2.1 Upper Plateau StrengthFIG. X2.2 Lower Plateau StrengthF2
41、516 145FIG. X2.3 Residual ElongationFIG. X2.4 Ultimate Tensile StrengthF2516 146ASTM 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 advised that determination of the val
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44、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 c
45、opies) 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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ X2.5 Uniform ElongationF2516 147
