1、Designation:E145009Standard Test Method forTension Testing of Structural Alloys in Liquid Helium1This standard is issued under the fixed designation E1450;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A nu
2、mber 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 procedures for the tensiontesting of structural alloys in liquid helium.The format issimilar to that of other ASTM
3、 tension test standards,but thecontents include modifications for cryogenic testing whichrequires special apparatus,smaller specimens,and concern forserrated yielding,adiabatic heating,and strain-rate effects.1.2 To conduct a tension test by this standard,the specimenin a cryostat is fully submerged
4、 in normal liquid helium(He I)and tested using crosshead displacement control at a nominalstrain rate of 103s1or less.Tests using force control or highstrain rates are not considered.1.3 This standard specifies methods for the measurement ofyield strength,tensile strength,elongation,and reduction of
5、area.The determination of the elastic modulus is treated in TestMethod E111.NOTE1The boiling point of normal liquid helium(He I)at sea levelis 4.2 K(269C or 452.1F or 7.6R).It decreases with geographicelevation and is 4.0 K(269.2C or 452.5F or 7.2R)at the NationalInstitute of Standards and Technolog
6、y in Colorado,1677 m(5500 ft)above sea level.In this standard the temperature is designated 4 K.1.4 Values stated in SI units are treated as primary.Valuesstated in U.S.customary units are treated as secondary.1.5 This standard does not purport to address all of thesafety concerns,if any,associated
7、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.See Section 5.2.Referenced Documents2.1 ASTM Standards:2A370 Test Methods and Definitions for Mechanical Tes
8、tingof Steel ProductsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE8/E8M Test Methods for Tension Testing of Metallic Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE83 Prac
9、tice for Verification and Classification of Exten-someter SystemsE111 Test Method for Youngs Modulus,Tangent Modulus,and Chord ModulusE1012 Practice for Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive AxialForce Application3.Terminology3.1 Definitions:3.1.1 The de
10、finitions of terms relating to tension testing thatappear in Terminology E6 shall apply here.The definitions inthis section also apply.3.1.2 adiabatic heatingthe internal heating of a specimenresulting from tension testing under conditions such that theheat generated by plastic work cannot be quickl
11、y dissipated tothe surrounding cryogen.3.1.3 adjusted length of the reduced sectionthe length ofthe reduced section plus an amount calculated to compensatefor strain in the fillet region.3.1.4 axial strainthe average of the longitudinal strainsmeasured at opposite or equally spaced surface locations
12、 on thesides of the longitudinal axis of symmetry of the specimen.Thelongitudinal strains are measured using two or more strain-sensing devices located at the mid-length of the reducedsection.3.1.5 bending strainthe difference between the strain atthe surface of the specimen and the axial strain(the
13、 bendingstrain varies around the circumference and along the reducedsection of the specimen).3.1.6 Dewara vacuum-insulated container for cryogenicfluids.3.1.7 discontinuous yielding stress,ithe peak stress at theinitiation of the first measurable serration on the curve ofstress-versus-strain.3.1.7.1
14、 DiscussionThe parameter iis a function of testvariables and is not a material constant.1This test method is under the jurisdiction of ASTM Committee E28 onMechanical Testing and is the direct responsibility of Subcommittee E28.04 onUniaxial Testing.Current edition approved June 1,2009.Published Aug
15、ust 2009.Originallyapproved in 1992.Last previous edition approved in 2003 as E1450 03.DOI:10.1520/E1450-09.2For 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
16、 Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.8 gage lengththe original distance between gagemarks made on the specimen for determining elongation afterfracture.3.1.9 length of the reduced sectionthe distance betweenthe tangent points of the fillets that bound the reduced section.3.1.10 maximum bending strainthe largest value of bend-ing strain in the reduced section of the specimen.3.1.
