1、Designation: E2714 13Standard 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 indica
2、tes 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
3、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 ox
4、idation). 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 cra
5、ckingvary 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 asses
6、sment 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
7、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 defor
8、mation 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
9、 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.NOTE 1A crack is believed to have formed when it has
10、 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 droptechni
11、que. 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.NOTE 2
12、The 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. Fo
13、r 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 al
14、l 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 For
15、ce 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 Fatiguea
16、nd 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 st
17、andards, 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 Conshohocken,
18、 PA 19428-2959. United States1and Chord ModulusE139 Test Methods for Conducting Creep, Creep-Rupture,and Stress-Rupture Tests of Metallic MaterialsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE220 Test Method for Calibration of Thermocouples ByComparison TechniquesE230 Sp
19、ecification and Temperature-Electromotive Force(EMF) Tables for Standardized ThermocouplesE467 Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing SystemE606 Practice for Strain-Controlled Fatigue TestingE647 Test Method for Measurement of Fatigue CrackGrowth
20、RatesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1012 Practice for Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive AxialForce ApplicationE1823 Terminology Relating to Fatigue and Fracture TestingE2368 Practice f
21、or Strain Controlled ThermomechanicalFatigue Testing2.2 BSI Standards:3BS 7270: 2000 Method for Constant Amplitude Strain Con-trolled Fatigue TestingBS 1041-4:1992 Temperature measurement Part 4: Guideto the selection and use of thermocouples2.3 CEN Standards:4EN 60584-11996 Thermocouples Reference
22、tables (IEC584-1)EN 60584 -2 1993 Thermocouples Tolerances (IEC584-2)PrEN 38741998 Test methods for metallic materials constant amplitude force-controlled low cycle fatiguetestingPrEN 39881998 Test methods for metallic materials constant amplitude strain-controlled low cycle fatiguetesting2.4 ISO St
23、andards:5ISO 121062003 Metallic materials Fatigue testing -Axialstrain-controlled methodISO 121112005 (Draft) Strain-controlled thermo-mechanical fatigue testing methodISO 7500-12004 Metallic materials Verification of staticuniaxial testing machines Part 1. Tension/compressiontesting machines Verifi
24、cation and calibration of the forcemeasuring systemISO 95131999 Metallic materials Calibration of exten-someters used in axial testingISO 57251994 Accuracy (trueness and precision) of mea-surement methods2.5 JIS Standard:6JIS Z 22791992 Method of high temperature low cyclefatigue testing for metalli
25、c materials3. Terminology3.1 The definitions in this test method that are also includedin Terminology E1823 are in accordance with TerminologyE1823.3.2 Symbols, standard definitions, and definitions specific tothis standard are in 3.2.1, 3.3, and 3.4, respectively.3.2.1 Symbols:Symbol Termd L Diamet
26、er of gage sectionof cylindrical test specimenDg, L Diameter of grip endsE, Eo,EN,FL-2 Elastic modulus, initial modulusof elasticity, modulus of elasticity at cycleET,ECFL-2 Tensile modulus,compressive modulusP F Forcel, loL Extensometer gage length,original extensometergage lengthL, Lo, L Length of
27、 parallel sectionof gage length, original lengthof parallel section of gage lengthN, NfCycle number, cycle numberto crack formationr,L Transition radius(from parallel section to grip end)min/ max,RStrain ratiomin/ max,RStress ratio TimeT Specimen temperatureTi Indicated specimentemperatureN versus m
28、axCrack formation or end-of-life criterion isexpressed as a percentage reduction inmaximum stress from the cycles,N versus maxcurve when the stressfalls sharply (see Fig. 1), or a specificpercentagedecrease in the modulus of elasticity ratiosin the tensile and compressive portionsof the hysteresis d
29、iagrams, or as aspecific increase in crack size asindicated by an electricpotential drop monitoring instrumentation., max, minStrain, maximum strain in the cycle,minimum strain in the cycleea, pa, taElastic strain amplitude,plastic strain amplitude,total strain amplitudee, p, tElastic strain range,
30、plastic strain range,total strain range (see Fig. 2)inInelastic strain range, (see Fig. 2) is the sum oftheplastic strain range and the creep strainsduring the cycle; it is the distance on thestrain axis between points of intersectionsof the strain axis and the extrapolated linearregions of the hyst
31、eresis loops duringtensile and compressive unloadings, max, minStress, maximum stress in the cycle,minimum stress in the cycle Stress range3Available from British Standards Institute (BSI), 389 Chiswick High Rd.,London W4 4AL, U.K., http:/www.bsi-.4Available from European Committee for Standardizati
32、on (CEN), 36 rue deStassart, B-1050, Brussels, Belgium, http:/www.cenorm.be.5Available from International Organization for Standardization (ISO), 1, ch. dela Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.6Available from Japanese Standards Organization (JSA), 4-1-24
33、AkasakaMinato-Ku, Tokyo, 107-8440, Japan, http:/www.jsa.or.jpE2714 1323.3 Definitions:3.3.1 cycleIn fatigue, one complete sequence of values offorce (strain) that is repeated under constant amplitude loading(straining)3.3.2 hold-time, hTIn fatigue testing, the amount oftime in the cycle where the co
34、ntrolled test variable (force,strain, displacement) remains constant with time (Fig. 3).3.3.2.1 DiscussionHold- time(s) are typically placed atpeak stress or strain in tension and/or compression, but can alsobe placed at other positions within the cycle.3.3.3 total cycle period, tT,The time for comp
35、letion ofone cycle. The parameter tcan be separated into hold (h) andnon-hold (nh) (that is, steady and dynamic) components,where the total cycle time is the sum of the hold time and thenon-hold time.3.3.4 hysteresis diagramThe stress-strain path during onecycle (see Fig. 2).3.3.5 initial modulus of
36、 elasticity, Eo, FL-2The modu-lus of elasticity determined during the loading portion of thefirst cycle.3.3.6 modulus of elasticity at cycle N, (EN, FL-2Theaverage of the modulus of elasticity determined during increas-ing load portion (see Ecin Fig. 2) and the decreasing loadportion (ETin Fig. 2) o
37、f the hysteresis diagram for the Nthcycle.3.3.7 stress range, , FL-2The difference between themaximum and minimum stresses.3.3.7.1 DiscussionFor creep-fatigue tests, the differencebetween the maximum and minimum stresses is called the“peak stress range” and for tests conducted under straincontrol, t
38、he difference between the stresses at the points ofreversal of the control parameter is called the “relaxed stressrange” (see Fig. 2b).3.4 Definitions of Terms Specific to This Standard:3.4.1 DCPD and ACPDDirect current and alternatingcurrent electrical potential drop crack monitoring instrumenta-ti
39、on.3.4.2 homologous temperatureThe specimen temperaturein K divided by the melting point of the material also in K.3.4.3 crack formationA crack is believed to have formedwhen it has nucleated and propagated in a specimen that wasinitially un-cracked to a size that is detectable by a statedtechnique.
40、4. Significance and Use4.1 Creep-fatigue testing is typically performed at elevatedtemperatures and involves the sequential or simultaneousapplication of the loading conditions necessary to generatecyclic deformation/damage enhanced by creep deformation/damage or vice versa. Unless such tests are pe
41、rformed invacuum or an inert environment, oxidation can also be respon-sible for important interaction effects relating to damageaccumulation. The purpose of creep-fatigue tests can be todetermine material property data for (a) assessment input datafor the deformation and damage condition analysis o
42、f engi-neering structures operating at elevated temperatures (b) theverification of constitutive deformation and damage modeleffectiveness (c) material characterization, or (d) developmentFIG. 1 Crack Formation and End-of-Test Criterion based on Reduction of Peak Stress for (a) Hardening and (b) Sof
43、tening MaterialsE2714 133and verification of rules for new construction and life assess-ment of high-temperature components subject to cyclic servicewith low frequencies or with periods of steady operation, orboth.4.2 In every case, it is advisable to have complementarycontinuous cycling fatigue dat
44、a (gathered at the same strain/loading rate) and creep data determined from test conducted asper Practice E139 for the same material and test tempera-ture(s). The procedure is primarily concerned with the testingof round bar test specimens subjected (at least remotely) touniaxial loading in either f
45、orce or strain control. The focus ofthe procedure is on tests in which creep and fatigue deforma-tion and damage is generated simultaneously within a givencycle. Data which may be determined from creep-fatigue testsperformed under such conditions may characterize (a) cyclicstress-strain deformation
46、response (b) cyclic creep (or relax-ation) deformation response (c) cyclic hardening, cyclic soft-ening response or (d) cycles to crack formation, or both.4.3 While there are a number of testing Standards andCodes of Practice that cover the determination of low cyclefatigue deformation and cycles to
47、 crack initiation properties(See Practice E606, BS 7270: 2000, JIS Z 22791992, PrEN3874, 1998, PrEN 39881998, ISO 121062003, ISO121112005, and Practice E2368-04 and (1, 2, 3)7, some ofwhich provide guidance for testing at high temperature (forexample, Practice E606, ISO 121062003, and PracticeE2368-
48、04, there is no single standard which specificallyprescribes a procedure for creep-fatigue testing.5. Functional Relationships5.1 Empirical relationships that have been commonly usedfor description of creep-fatigue data are given in Appendix X1.These relationships typically have limitations with res
49、pect tomaterial types such as high temperature ferritic and austeniticsteels versus nickel base alloys. Therefore, original data shouldbe reported to the greatest extent possible. Data reductionmethods should be detailed along with assumptions. Sufficientinformation should be recorded and reported to permitanalysis, interpretation, and comparison with results for othermaterials analyzed using currently popular methods.6. Apparatus6.1 Test machines:7
