ASTM_E_2714_-_13.pdf

Designation:E271413Standard Test Method forCreep-Fatigue Testing1This standard is issued under the fixed designation E2714;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of 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.Scope1.1 This test method covers the determination of mechanicalproperties pertaining to creep-fatigue deformation or crackformation in nominally homogeneous materials,or both by theuse of test specimens subjected to uniaxial forces underisothermal conditions.It concerns fatigue testing at strain ratesor with cycles involving sufficiently long hold times to beresponsible for the cyclic deformation response and cycles tocrack formation to be affected by creep(and oxidation).It isintended as a test method for fatigue testing performed insupport of such activities as materials research anddevelopment,mechanical design,process and quality control,product performance,and failure analysis.The cyclic condi-tions responsible for creep-fatigue deformation and crackingvary with material and with temperature for a given material.1.2 The use of this test method is limited to specimens anddoes not cover testing of full-scale components,structures,orconsumer products.1.3 This test method is primarily aimed at providing thematerial properties required for assessment of defect-freeengineering structures containing features that are subject tocyclic loading at temperatures that are sufficiently high to causecreep deformation.1.4 This test method is applicable to the determination ofdeformation and crack formation or nucleation properties as aconsequence of either constant-amplitude strain-controlledtests or constant-amplitude force-controlled tests.It is primar-ily concerned with the testing of round bar test specimenssubjected to uniaxial loading in either force or strain control.The focus of the procedure is on tests in which creep andfatigue deformation and damage is generated simultaneouslywithin a given cycle.It does not cover block cycle testing inwhich creep and fatigue damage is generated sequentially.Datathat may be determined from creep-fatigue tests performedunder conditions in which creep-fatigue deformation anddamage is generated simultaneously include(a)cyclic stress-strain deformation response(b)cyclic creep(or relaxation)deformation response(c)cyclic hardening,cyclic softeningresponse(d)cycles to formation of a single crack or multiplecracks in test specimens.NOTE1A crack is believed to have formed when it has nucleated andpropagated in a specimen that was initially uncracked to a specific sizethat is detectable by a stated technique.For the purpose of this standard,the formation of a crack is evidenced by a measurable increase incompliance of the specimen or by a size detectable by potential droptechnique.Specific details of how to measure cycles to crack formationare described in 9.5.1.1.5 This test method is applicable to temperatures and strainrates for which the magnitudes of time-dependent inelasticstrains(creep)are on the same order or larger than time-independent inelastic strain.NOTE2The term inelastic is used herein to refer to all nonelasticstrains.The term plastic is used herein to refer only to time independent(that is,non-creep)component of inelastic strain.A useful engineeringestimate of time-independent strain can be obtained when the strain rateexceeds some value.For example,a strain rate of 110-3sec-1is oftenused for this purpose.This value should increase with increasing testtemperature.1.6 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.7 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.Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE8/E8M Test Methods for Tension Testing of Metallic Ma-terialsE83 Practice for Verification and Classification of Exten-someter SystemsE111 Test Method for Youngs Modulus,Tangent Modulus,1This test method is under the jurisdiction of ASTM Committee E08 on Fatigueand Fracture and is the direct responsibility of Subcommittee E08.05 on CyclicDeformation and Fatigue Crack Formation.Current edition approved June 15,2013.Published July 2013.Originallyapproved in 2009.Last previous edition approved in 2009 as E2714091.DOI:10.1520/E271413.2For 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 Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor