1、Designation:F251614Standard 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 last revision.
2、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 covers the tension testing of superelas-tic nickel-titanium(nitinol)materials,specifically the methodsfor determination
3、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 thesafety concerns,if an
4、y,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 Methods of Mechanical Test
5、ingE8 Test Methods for Tension Testing of Metallic MaterialsE83 Practice for Verification and Classification of Exten-someter SystemsE111 Test Method for Youngs Modulus,Tangent Modulus,and Chord ModulusE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conduct
6、ing an Interlaboratory Study toDetermine the Precision of a Test MethodE1876 Test Method for Dynamic Youngs Modulus,ShearModulus,and Poissons Ratio by Impulse Excitation ofVibrationF2005 Terminology for Nickel-Titanium Shape MemoryAlloys3.Terminology3.1 The definitions of terms relating to tension t
7、estingappearing in Terminology E6 and the terms relating to nickel-titanium shape memory alloys appearing in TerminologyF2005 shall be considered as applying to the terms used in thistest method.Additional terms being defined are as follows(seeFig.1):3.2 Definitions:3.2.1 lower plateau strength(LPS)
8、the stress at 2.5%strain during unloading of the sample,after loading to 6%strain.3.2.2 residual elongation,Elr%the difference betweenthe strain at a stress of 7.0 MPa during unloading and the strainat a stress of 7.0 MPa during loading.3.2.3 uniform elongation,Elu%the elongation deter-mined at the
9、maximum force sustained by the test piece justprior to necking,or fracture,or both.3.2.4 upper plateau strength(UPS)the stress at 3%strainduring 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 th
10、an 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 tests,as described in this test method,alsoprovide information on the superelasticity,as defined in Ter-minology F2005,of
11、the material at the test temperature.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:1This test method is under the jurisdiction ofASTM
12、Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Oct.1,2014.Published February 2015.Originallyapproved in 2005.Last previous edition approved in 2007 as F2516 072.DOI:10.1520/F2516-14.2
13、For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West
14、 Conshohocken,PA 19428-2959.United States1 8.1.1 Unless otherwise specified,the temperature of the testshall be 22.0 6 2.0C.It is recommended that the material betested at a temperature that is a minimum of 5C above theaustenitic finish transformation temperature(Af)in order toprevent testing of a p
15、artially transformed material.8.1.2 The free-running crosshead speed 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 spec
16、imen 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-mined by use of an extensometer or by crosshead motion.When using crosshead motion to calculate strain,the lengthbetween the grips must be 150 mm.NOTE1It is recommended that strain be measured using extensometerversus crosshead displacement as this will
