ASTM F2516-2007e1 Standard Test Method for Tension Testing of Nickel-Titanium Superelastic Materials.pdf

1、Designation: F 2516 07e1Standard Test Method forTension Testing of Nickel-Titanium Superelastic Materials1This standard is issued under the fixed designation F 2516; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last

2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEReferenced Documents were updated editorially in April 2008.1. Scope1.1 This test method covers the tension testing of superelas

3、-tic nickel-titanium (nitinol) materials, specifically the methodsof determination of upper plateau strength, lower plateaustrength, residual elongation, tensile strength, and elongation.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in th

4、isstandard.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. R

5、eferenced Documents2.1 ASTM Standards:2E6 Terminology Relating to Methods of Mechanical Test-ingE8 Test Methods for Tension Testing of Metallic MaterialsE83 Practice for Verification and Classification of Exten-someter SystemsE 111 Test Method for Youngs Modulus, Tangent Modulus,and Chord ModulusE 1

6、77 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 1876 Test Method for Dynamic Youngs Modulus, ShearModulus, and Poissons Ratio by Impulse Excitation ofVibrationF 2005 Terminology

7、for Nickel-Titanium Shape MemoryAlloys3. Terminology3.1 DefinitionsThe definitions of terms relating to tensiontesting appearing in Terminology E6and the terms relating tonickel-titanium shape memory alloys appearing in Terminol-ogy F 2005 shall be considered as applying to the terms used inthis tes

8、t method. Additional terms being defined are as follows(see Fig. 1):3.1.1 lower plateau strength (LPS)the stress at 2.5 %strain during unloading of the sample, after loading to 6 %strain.3.1.2 residual elongation, Elr%the difference betweenthe strain at a stress of 7.0 MPa during unloading and the s

9、trainat a stress of 7.0 MPa during loading.3.1.3 uniform elongation, Elu%the elongation deter-mined at the maximum force sustained by the test piece justprior to necking, or fracture, or both.3.1.4 upper plateau strength (UPS)the stress at 3 % strainduring loading of the sample.4. Summary of Test Me

10、thod4.1 Using conventional tensile testing apparatus, the mate-rial is pulled to 6 % strain, then unloaded to less than 7 MPa,then pulled to failure.5. Significance and Use5.1 Tension tests provide information on the strength andductility of materials under uniaxial tensile stresses.5.2 Tension test

11、s, as described in this test method, alsoprovide information on the superelasticity, as defined in Ter-minology F 2005, of the material at the test temperature.6. Apparatus6.1 Apparatus is as described in Test Methods E8.1This test method is under the jurisdiction of ASTM Committee F04 on Medicaland

12、 Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Dec. 1, 2007. Published January 2008. Originallyapproved in 2005. Last previous edition approved in 2006 as F 2516 06.2For referenced ASTM standards, visit the AST

13、M 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Unite

14、d States.7. Test Specimen7.1 Test specimens are as described in Test Methods E8.8. Procedure8.1 Procedure shall be per Test Methods E8 with thefollowing additions:8.1.1 Unless otherwise specified, the temperature of the testshall be 22.0C. Tolerance shall be 62.0C.8.1.2 Free-running crosshead speed

15、shall be limited perTable 1.8.1.3 The test shall consist of zeroing the force transducer,gripping the specimen, pulling the specimen to 6 % strain,reversing the motion to unload the specimen to less than 7MPa, and then pulling the specimen to failure.8.1.4 For materials with diameter greater than 0.

16、2 mm,strain shall be determined by use of a calibrated extensometerof class C or better (see Practice E83). For materials withdiameter less than or equal to 0.2 mm, strain may be deter-mined by use of an extensometer or by crosshead motion.When using crosshead motion to calculate strain, the lengthb

17、etween the grips must be 150 mm.8.1.4.1 When using a clip-on extensometer with smalldiameter wire, care must be taken not to bend or distort thewire when attaching the extensometer.8.1.5 Upper plateau strength shall be determined as thevalue of the stress at a strain of 3.0 % during the initial load

18、ingof the specimen.8.1.6 Lower plateau strength shall be determined as thevalue of the stress at a strain of 2.5 % during the unloading ofthe specimen.8.1.7 Residual elongation shall be determined by the differ-ence between the strain at a stress of 7.0 MPa during unloadingand the strain at a stress

19、 of 7.0 MPa during loading.8.1.8 The uniform elongation shall be determined by elon-gation when the maximum force is reached just prior tonecking or fracture, or both.9. Report9.1 The report shall include the following information,unless otherwise specified:9.1.1 Material and sample identification,9

20、.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 (extensometer or cross-head),9.1.10 Crosshead speed, and9.1.11 Gage length (length of reduce

21、d section or distancebetween grips for specimens not having reduced sections).10. Precision and Bias310.1 An interlaboratory study was conducted in accordancewith Practice E 691 using three different diameters of super-elastic wire. For wire diameters of 0.2 and 0.5 mm, elevenlaboratories participat

22、ed in the study with each laboratoryobtaining three results for each diameter. For the 2.5 mmdiameter wire, eight laboratories participated in the study witheach laboratory obtaining three results. The details are given inASTM Research Report RR: F041010.310.2 The results are summarized in Tables 2-

23、6 for eachtensile parameter. The terms repeatability limit and reproduc-ibility limit are used as specified in Practice E 177.10.3 No measurement of bias is possible with this testmethod since there is presently no accepted reference material.11. Keywords11.1 lower plateau strength; nickel titanium;

24、 nitinol; re-sidual elongation; shape memory; superelasticity; upper pla-teau strength3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: F041010.FIG. 1 Terms Illustrated on Typical Stress-Strain Diagram ofSuperelastic NitinolTABLE

25、 1 Crosshead Speed Limitsd, diameter orthickness (mm)AMaximum crosshead speed in mm/min. of initiallength of reduced section (or initial distancebetween grips for specimens not havingreduced sections)First Cycle(load to 6 % strainand unload)Second Cycle(load to failure)d # 0.2 0.08 0.80.2 2.5 0.01 0

26、.1AFor tubing, use d that gives equivalent surface area to diameter ratio; for roundtubing, d = (outer diameter) (inner diameter).F251607e12APPENDIXES(Nonmandatory Information)X1. RATIONALEX1.1 During tensile testing of superelastic nitinol material,heat is given off during the austenite-to-martensi

27、te transforma-tion. Strain rate is limited to allow the heat to transfer out of thespecimen. Otherwise the increase in specimen temperature willinfluence the stress-strain response.4X1.2 Measurement of modulus of elasticity requires veryprecise measurements beyond the scope of this standard. TestMet

28、hods E 111 and E 1876 address determination of modulusof elasticity. For superelastic nitinol, the dynamic method (TestMethod E 1876) is preferred. Note that the modulus of elas-ticity exhibits large variation with the martensitic transforma-tion.5X1.3 Due to experimental problems associated with th

29、eestablishment of the origin of the stress-strain curve, such asmechanical backlash, initial grip alignment, and specimencurvature, residual elongation may be negative at zero force. Inaddition, force transducers are typically not calibrated at zeroforce. For these reasons, the residual elongation i

30、s measuredwhile there is a small stress of 7 MPa on the sample.4Shaw, J. A. and Kyriakides, S., “On the Nucleation and Propagation of PhaseTransformation Fronts in a NiTi Alloy”, Acta Mater, Vol 45, No. 2, 1997, pp.683700.5Spinner, S. and Rozner, A. G., “Elastic Properties of NiTi as a Function ofTe

31、mperature”, The Journal of Acoustical Society of America, Vol. 40, No. 5, 1966,pp. 10091015.TABLE 2 Precision of Upper Plateau Strength (MPa)Diameter (mm) Grand Mean RepeatabilityStandard DeviationReproducibilityStandard DeviationRepeatabilityLimitReproducibilityLimit0.2 499 13 55 36 1540.5 492 11 3

32、5 30 982.5 500 13 25 35 71TABLE 3 Precision of Lower Plateau Strength (MPa)Diameter (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 (

33、%)Diameter (mm) Grand Mean RepeatabilityStandard DeviationReproducibilityStandard 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 Repeatabilit

34、yStandard DeviationReproducibilityStandard DeviationRepeatabilityLimitReproducibilityLimit0.2 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 DeviationRepeatabilityL

35、imitReproducibilityLimit0.2 11.5 0.7 1.2 2.0 3.50.5 12.4 0.4 1.0 1.3 2.82.5 13.3 0.6 0.7 1.8 1.9F251607e13X1.4 Use of crosshead motion to calculate strain is allowedfor small wires due to the possibility of distorting the wire withclip-on type extensometers. In this case, a minimum lengthbetween gri

36、ps is specified to minimize elongation errors due todeflection of the testing equipment. Another alternative is touse a non-contacting video extensometer.X2. INTERLABORATORY TEST RESULTSX2.1 The details of the interlaboratory study are given inASTM Research Report F041010. The data used to generatet

37、he precision statistics are charted below in Figs. X2.1-X2.5.FIG. X2.1 Upper Plateau StrengthF251607e14FIG. X2.2 Lower Plateau StrengthFIG. X2.3 Residual ElongationF251607e15ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mention

38、edin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and

39、 must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of

40、 theresponsible technical committee, which you may attend. If you 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

41、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).FIG. X2.4 Ultimate Tensile StrengthFIG. X2.5 Uniform ElongationF251607e16