1、Designation: E 606 04e1Standard Practice forStrain-Controlled Fatigue Testing1This standard is issued under the fixed designation E 606; 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 parenth
2、eses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTESection 10 was editorially revised in July 2005.1. Scope1.1 This practice covers the determination of fatigue prop-erties of nominally homogeneous materials
3、by the use of testspecimens subjected to uniaxial forces. It is intended as a guidefor fatigue testing performed in support of such activities asmaterials research and development, mechanical design, pro-cess and quality control, product performance, and failureanalysis. While this practice is inten
4、ded primarily for strain-controlled fatigue testing, some sections may provide usefulinformation for force-controlled or stress-controlled testing.1.2 The use of this practice is limited to specimens and doesnot cover testing of full-scale components, structures, orconsumer products.1.3 This practic
5、e is applicable to temperatures and strainrates for which the magnitudes of time-dependent inelasticstrains are on the same order or less than the magnitudes oftime-independent inelastic strains. No restrictions are placedon environmental factors such as temperature, pressure, hu-midity, medium, and
6、 others, provided they are controlledthroughout the test, do not cause loss of or change in dimensionwith time, and are detailed in the data report.NOTE 1The term inelastic is used herein to refer to all nonelasticstrains. The term plastic is used herein to refer only to the time-independent (that i
7、s, noncreep) component of inelastic strain. To trulydetermine a time-independent strain the force would have to be appliedinstantaneously, which is not possible. A useful engineering estimate oftime-independent strain can be obtained when the strain rate exceeds somevalue. For example, a strain rate
8、 of 1 3 103sec1is often used for thispurpose. This value should increase with increasing test temperature.1.4 This practice is restricted to the testing of uniform gagesection test specimens subjected to axial forces as shown inFig. 1(a). Testing is limited to strain-controlled cycling. Thepractice
9、may be applied to hourglass specimens, see Fig. 1(b),but the user is cautioned about uncertainties in data analysisand interpretation. Testing is done primarily under constantamplitude cycling and may contain interspersed hold times atrepeated intervals. The practice may be adapted to guidetesting f
10、or more general cases where strain or temperature mayvary according to application specific histories. Data analysismay not follow this practice in such cases.2. Referenced Documents2.1 ASTM Standards:2A 370 Test Methods and Definitions for Mechanical Testingof Steel ProductsE3 Practice for Preparat
11、ion of Metallographic SpecimensE4 Practices for Force Verification of Testing MachinesE8 Test Methods for Tension Testing of Metallic MaterialsE9 Test Methods of Compression Testing of Metallic Ma-terials at Room TemperatureE83 Practice for Verification and Classification of Exten-someter SystemE 11
12、1 Test Method forYoungs Modulus, Tangent Modulus,and Chord ModulusE112 Test Methods for Determining Average Grain SizeE 132 Test Method for Poissons Ratio at Room Tempera-tureE 157 Practice forAssigning Crystallographic Phase Desig-nations in Metallic Systems3E 177 Practice for Use of the Terms Prec
13、ision and Bias inASTM Test MethodsE 209 Practice for Compression Tests of Metallic Materialsat Elevated Temperatures with Conventional or RapidHeating Rates and Strain RatesE 337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)E 384 Test Me
14、thod for Microindentation Hardness of Ma-terialsE 399 Test Method for Plane-Strain Fracture Toughness ofMetallic MaterialsE 466 Practice for Conducting Force Controlled Constant1This practice is under the jurisdiction ofASTM Committee E08 on Fatigue andFracture and is the direct responsibility of Su
15、bcommittee E08.05 on CyclicDeformation and Fatigue Crack Formation.Current edition approved July 20, 2005. Published October 2004. Originallyapproved in 1977. Last previous edition approved in 2004 as E 606 92(2004)e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AS
16、TM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Amplitude Axial F
17、atigue Tests of Metallic MaterialsE 467 Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing SystemE 468 Practice for Presentation of Constant Amplitude Fa-tigue Test Results for Metallic MaterialsE 691 Practice for Conducting an Interlaboratory Study toDetermi
18、ne the Precision of a Test MethodE 739 Practice for Statistical Analysis of Linear or Linear-ized Stress-Life (S-N) and Strain-Life (e-N) Fatigue DataE 1012 Practice for Verification of Specimen AlignmentUnder Tensile LoadingE 1049 Practices for Cycle Counting in Fatigue AnalysisE 1823 Terminology R
19、elating to Fatigue and Fracture Test-ing3. Terminology3.1 The definitions in this practice are in accordance withTerminology E 1823.3.2 Additional definitions associated with time-dependentdeformation behavior observed in tests at elevated homologoustemperatures are as follows:3.2.1 hold period, tht
20、he time interval within a cycleduring which the stress or strain is held constant.3.2.2 inelastic strain, einthe strain that is not elastic. Forisothermal conditions, einis calculated by subtracting theelastic strain from the total strain.3.2.3 total cycle period, ttthe time for the completion ofone
21、 cycle. The parameter ttcan be separated into hold andnonhold components:tt5 (th1 (tnh(1)where:(th= sum of all the hold portions of the cycle and(tnh= sum of all the nonhold portions of the cycle.ttalso is equal to the reciprocal of the overall frequency whenthe frequency is held constant.3.2.4 The
22、following equations are often used to define theinstantaneous stress and strain relationships for many metalsand alloys:e5ein1ee(2)ee5sE*see Note 2!and the change in strain from any point (1) to any other point(3), as illustrated in Fig. 2, can be calculated as follows:NOTE 1* Dimension d is recomme
23、nded to be 6.35 mm (0.25 in.). See 7.1. Centers permissible. * This diameter may be made greater or less than2d depending on material hardness. In typically ductile materials diameters less than 2d are often employed and in typically brittle materials diametersgreater than 2d may be found desirable.
24、FIG. 1 Recommended Low-Cycle Fatigue SpecimensE60604e12e32e15Se3in1s3E*D2Se1in1s1E*D(3)All strain points to the right of and all stress points above theorigin are positive. The equation would then show an increasein inelastic strain from 1 to 3 or:e3in2e1in5e32e11s1E*2s3E*(4)Similarly, during the st
25、rain hold period, the change in theinelastic strain will be equal to the change in the stress dividedby E*, or:e3in2e2in5s22s3E*(5)NOTE 2E* represents a material parameter that may be a function ofenvironment and test conditions. It also may vary during a test as a resultof metallurgical or physical
26、 changes in the specimen. In many instances,however, E* is practically a constant quantity and is used rather exten-sively in isothermal, constant-rate testing, in the analysis of hysteresisloops. In such cases, a value for E* can best be determined by cycling thespecimen prior to the test at stress
27、 or strain levels below the elastic limit.E* is NOT the monotonic Youngs modulus.4. Significance and Use4.1 Strain-controlled fatigue is a phenomenon that is influ-enced by the same variables that influence force-controlledfatigue. The nature of strain-controlled fatigue imposes distinc-tive require
28、ments on fatigue testing methods. In particular,cyclic total strain should be measured and cyclic plastic strainshould be determined. Furthermore, either of these strainstypically is used to establish cyclic limits; total strain usually iscontrolled throughout the cycle. The uniqueness of this prac-
29、tice and the results it yields are the determination of cyclicstresses and strains at any time during the tests. Differences instrain histories other than constant-amplitude alter fatigue lifeas compared with the constant amplitude results (for example,periodic overstrains and block or spectrum hist
30、ories). Like-wise, the presence of nonzero mean strains and varyingenvironmental conditions may alter fatigue life as comparedwith the constant-amplitude, fully reversed fatigue tests. Caremust be exercised in analyzing and interpreting data for suchcases. In the case of variable amplitude or spectr
31、um strainhistories, cycle counting can be performed with PracticeE 1049 .4.2 Strain-controlled fatigue can be an important consider-ation in the design of industrial products. It is important forsituations in which components or portions of componentsundergo either mechanically or thermally induced
32、cyclic plas-tic strains that cause failure within relatively few (that is,approximately 105) cycles. Information obtained from strain-controlled fatigue testing may be an important element in theestablishment of design criteria to protect against componentfailure by fatigue.4.3 Strain-controlled fat
33、igue test results are useful in theareas of mechanical design as well as materials research anddevelopment, process and quality control, product perfor-mance, and failure analysis. Results of a strain-controlledfatigue test program may be used in the formulation ofempirical relationships between the
34、 cyclic variables of stress,total strain, plastic strain, and fatigue life. They are commonlyused in data correlations such as curves of cyclic stress or strainversus life and cyclic stress versus cyclic plastic strain obtainedfrom hysteresis loops at some fraction (often half) of materiallife. Exam
35、ination of the cyclic stressstrain curve and itscomparison with monotonic stressstrain curves gives usefulinformation regarding the cyclic stability of a material, forexample, whether the values of hardness, yield strength,ultimate strength, strain-hardening exponent, and strengthcoefficient will in
36、crease, decrease, or remain unchanged (thatis, whether a material will harden, soften, or be stable) becauseof cyclic plastic straining (1).4The presence of time-dependentinelastic strains during elevated temperature testing providesthe opportunity to study the effects of these strains on fatiguelif
37、e and on the cyclic stress-strain response of the material.Information about strain rate effects, relaxation behavior, andcreep also may be available from these tests. Results of theuniaxial tests on specimens of simple geometry can be appliedto the design of components with notches or other complex
38、shapes, provided that the strains can be determined andmultiaxial states of stress or strain and their gradients arecorrectly correlated with the uniaxial strain data.5. Functional Relationships5.1 Empirical relationships that have been commonly usedfor description of strain-controlled fatigue data
39、are given inAppendix X1. These relationships may not be valid when largetime-dependent inelastic strains occur. For this reason originaldata should be reported to the greatest extent possible. Datareduction methods should be detailed along with assumptions.Sufficient information should be developed
40、and reported topermit analysis, interpretation, and comparison with results forother materials analyzed using currently popular methods.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.FIG. 2 Analyses of a Total Strain versus Stress Hystersis LoopContai
41、ning a Hold PeriodE60604e135.2 If use is made of hourglass geometries, original datashould be reported along with results analyzed using therelationships in Appendix X2.6. Methodology6.1 Testing MachineTesting should be conducted with atension-compression fatigue testing machine that has beenverifie
42、d in accordance with Practices E 4 and E 467, unlessmore stringent requirements are called for in this specification.The testing machine, together with any fixtures used in the testprogram, must meet the bending strain criteria in 6.3.1. Themachine should be one in which specific measures have beent
43、aken to minimize backlash in the loading train.NOTE 3Force measuring capability of 45 kN (approximately 10 kips)or greater would be sufficient for the recommended specimens (Section 7)and most test materials. The machine force capacity used for thesespecimens would not be required to exceed 110 kN (
44、approximately 25kips); however, large-capacity fatigue machines may be beneficial becauseof increased axial stiffness and decreased lateral deflection of thesesystems.Achieving a change in axial concentricity of less than or equal to0.05 mm (0.002 in.) TIR (total indicator reading), as measured betw
45、eenthe top and bottom specimen fixture under cyclic force, is a measure ofsuccess with respect to minimizing lateral deflection of the loading train.6.2 Strain ControlTesting machine controls should permitcycling between constant strain limits. If material behaviorpermits (for example, aging effects
46、 do not hinder), controlstability should be such that the strain maximum and minimumlimits are repeatable over the test duration to within 1 % of therange between maximum and minimum control limits.NOTE 4See 6.4.1 and 6.5 on use of force and strain transducers inrelation to repeatability requirement
47、s.NOTE 5For strain control under long-life conditions it is sometimesadvantageous to run a pseudostrain control test under force control. Thetest could be started in strain control and switched to force control aftercyclic stabilization of the stress response occurs. In these cases strainshould be m
48、onitored (directly or indirectly) and adjustments made in forcecontrol to maintain strain limits within 1 % of the range betweenmaximum and minimum limits. Practice E 466 provides additional detailson force controlled axial fatigue testing.6.3 Fixtures:6.3.1 To minimize bending strains, specimen fix
49、tures shouldbe aligned such that the major axis of the specimen closelycoincides with the force axis throughout each cycle. It isimportant that the accuracy of alignment be kept consistentfrom specimen to specimen. Alignment should be checked bymeans of a trial test specimen with longitudinal strain gagesplaced at four equidistant locations around the minimumdiameter. The trial test specimen should be turned about itsaxis, installed, and checked for each of four orientations withinthe fixtures. The maximum bending strains so determinedshould not exceed 5 % of the
