1、Designation: F 2516 06Standard 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 re
2、vision. 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 covers the tension testing of superelas-tic nickel-titanium (nitinol) materials, specifically the methodsof
3、 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 thisstandard.1.3 This standard does not purport to address all of thes
4、afety 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. Referenced Documents2.1 ASTM Standards:2E6 Terminology Relating to Me
5、thods 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 1875 Test Method for Dynamic Youngs Modulus, ShearModulus, and Poisso
6、ns Ratio by Sonic ResonanceF 2005 Terminology 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 consi
7、dered as applying to the terms used inthis test 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
8、a stress of 7.0 MPa during unloading and the strainat 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 % strainduri
9、ng loading of the sample.4. Summary of Test Method4.1 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 of the strength andductility of materials un
10、der uniaxial tensile stresses.5.2 Tension tests, 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.1This test method is under the jurisdiction of ASTM Committee F04 on Medicaland Surgical Mater
11、ials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved June 1, 2006. Published June 2006. Originallyapproved in 2005. Last previous edition approved in 2005 as F 2516 05.2For referenced ASTM standards, visit the ASTM website, www.ast
12、m.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.FIG. 1 Terms Illustrated on Typical Stress-Strain Diagram ofSuperelastic Nitinol1Copyright ASTM International, 100 Barr Harb
13、or Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 Apparatus is as described in Test 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 thefollowing additions:8.1.1 Unless o
14、therwise specified, temperature of test shallbe 22.0C. Tolerance shall be 62.0C.8.1.2 Free-running crosshead speed shall be limited perTable 1.8.1.3 Test shall consist of zeroing the force transducer,gripping the specimen, pulling the specimen to 6 % strain,reversing the motion to unload the specime
15、n to less than 7MPa, 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 calibrated extensometerof class C or better (see Practice E83). For materials withdiameter less than or equal to 0.2 mm, strain may be deter-mine
16、d by use of an extensometer or by crosshead motion.When using crosshead motion to calculate strain, the lengthbetween 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 Up
17、per plateau strength shall be determined by thestress at a strain of 3.0 % during the initial loading of thespecimen.8.1.6 Lower plateau strength shall be determined by thestress at a strain of 2.5 % during the unloading of the specimen.8.1.7 Residual elongation shall be determined by the differ-enc
18、e between the strain at a stress of 7.0 MPa during unloadingand the strain at a stress of 7.0 MPa during loading.8.1.8 The uniform elongation shall be determined by elon-gation when the maximum load is reached just prior to neckingor fracture, or both.9. Report9.1 The report shall include the follow
19、ing information,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 (extens
20、ometer or cross-head),9.1.10 Crosshead speed, and9.1.11 Gage length (length of reduced section or distancebetween grips for specimens not having reduced sections).10. Precision and Bias10.1 The precision and bias of this test method is to beestablished.11. Keywords11.1 lower plateau strength; nickel
21、 titanium; nitinol; re-sidual elongation; shape memory; superelasticity; upper pla-teau strengthAPPENDIX(Nonmandatory Information)X1. RATIONALEX1.1 During tensile testing of superelastic nitinol material,heat is given off during the austenite to martensite transforma-tion. Strain rate is limited to
22、allow the heat to transfer out of thespecimen. Otherwise the increase in specimen temperature willinfluence the stress-strain response.3X1.2 Measurement of modulus requires very precise mea-surements beyond the scope of this standard. Test MethodsE 111 and E 1875 address determination of modulus. Fo
23、rsuperelastic nitinol, the dynamic method (Test Method E 1875)is preferred. Note that the modulus exhibits large variation withthe martensitic transformation.4X1.3 Due to experimental problems associated with the3Shaw, J. A. and Kyriakides, S., “On the Nucleation and Propagation of PhaseTransformati
24、on Fronts in a NiTi Alloy”, Acta Mater, Vol 45, No. 2, 1997, pp.683700.4Spinner, S. and Rozner, A. G., “Elastic Properties of NiTi as a Function ofTemperature”, The Journal of Acoustical Society of America, Vol. 40, No. 5, 1966,pp. 10091015.TABLE 1 Crosshead Speed Limitsd, diameter orthickness (mm)A
25、Maximum crosshead speed in mm/min. per mmof initial length of reduced section (or initialdistance between grips for specimens nothaving reduced 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 0.1AFor tubing, use d that gives equivalent surf
26、ace area to diameter ratio; for roundtubing, d = (outer diameter) (inner diameter).F2516062establishment of the origin of the stress-strain curve, such asmechanical slop, initial grip alignment, and specimen curva-ture, residual elongation may be negative at zero load. Inaddition, force transducers
27、are typically not calibrated at zeroload. For these reasons, the residual elongation is measuredwhile there is a small load 7 MPa on the sample.X1.4 Use of crosshead motion to calculate strain is allowedfor small wires due to the possibility of distorting the wire withclip-on type extensometers. In
28、this case, a minimum lengthbetween grips is specified to minimize elongation errors due todeflection of the testing equipment. Another alternative is touse a non-contacting video extensometer.ASTM International takes no position respecting the validity of any patent rights asserted in connection wit
29、h any item mentionedin 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 techn
30、ical committee and 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 considerati
31、on at a meeting of 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 Har
32、bor 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).F2516063
