1、Designation: E466 07E466 15Standard Practice forConducting Force Controlled Constant Amplitude AxialFatigue Tests of Metallic Materials1This standard is issued under the fixed designation E466; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 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 practice covers the procedure for the performance of axial force controlled fatigue tests
3、to obtain the fatigue strengthof metallic materials in the fatigue regime where the strains are predominately elastic, both upon initial loading and throughoutthe test. This practice is limited to the fatigue testing of axial unnotched and notched specimens subjected to a constant amplitude,periodic
4、 forcing function in air at room temperature. This practice is not intended for application in axial fatigue tests ofcomponents or parts.NOTE 1The following documents, although not directly referenced in the text, are considered important enough to be listed in this practice:E739 Practice for Statis
5、tical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (-N) Fatigue DataSTP 566 Handbook of Fatigue Testing2STP 588 Manual on Statistical Planning and Analysis for Fatigue Experiments3STP 731 Tables for Estimating Median Fatigue Limits42. Referenced Documents2.1 ASTM Standards:5E3
6、Guide for Preparation of Metallographic SpecimensE467 Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing SystemE468 Practice for Presentation of Constant Amplitude Fatigue Test Results for Metallic MaterialsE606E606/E606M Test Method for Strain-Controlled Fati
7、gue TestingE739 Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (-N) Fatigue DataE1012 Practice for Verification of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial ForceApplicationE1823 Terminology Relating to Fatigue and Fracture
8、Testing3. Terminology3.1 Definitions:3.1.1 The terms used in this practice shall be as defined in Terminology E1823.4. Significance and Use4.1 The axial force fatigue test is used to determine the effect of variations in material, geometry, surface condition, stress, andso forth, on the fatigue resi
9、stance of metallic materials subjected to direct stress for relatively large numbers of cycles. The resultsmay also be used as a guide for the selection of metallic materials for service under conditions of repeated direct stress.4.2 In order to verify that such basic fatigue data generated using th
10、is practice is comparable, reproducible, and correlatedamong laboratories, it may be advantageous to conduct a round-robin-type test program from a statisticians point of view. To doso would require the control or balance of what are often deemed nuisance variables; for example, hardness, cleanlines
11、s, grain size,1 This practice is under the jurisdiction of ASTM Committee E08 on Fatigue and Fracture and is the direct responsibility of Subcommittee E08.05 on Cyclic Deformationand Fatigue Crack Formation.Current edition approved Nov. 1, 2007May 1, 2015. Published November 2007June 2015. Originall
12、y approved in 1972. Last previous edition approved in 20022007 asE466 96E466 07.(2002)1 . DOI: 10.1520/E0466-07.10.1520/E0466-15.2 Handbook of Fatigue Testing,ASTM STP 566, ASTM, 1974.3 Little, R. E., Manual on Statistical Planning and Analysis, ASTM STP 588, ASTM, 1975.4 Little, R. E., Tables for E
13、stimating Median Fatigue Limits,ASTM STP 731, ASTM, 1981.5 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This
14、 document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior edition
15、s as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1composition, directionality, surface residual stress
16、, surface finish, and so forth. Thus, when embarking on a program of this natureit is essential to define and maintain consistency a priori, as many variables as reasonably possible, with as much economy asprudent.All material variables, testing information, and procedures used should be reported so
17、 that correlation and reproducibilityof results may be attempted in a fashion that is considered reasonably good current test practice.4.3 The results of the axial force fatigue test are suitable for application to design only when the specimen test conditionsrealistically simulate service condition
18、s or some methodology of accounting for service conditions is available and clearly defined.5. Specimen Design5.1 The type of specimen used will depend on the objective of the test program, the type of equipment, the equipment capacity,and the form in which the material is available. However, the de
19、sign should meet certain general criteria outlined below:5.1.1 The design of the specimen should be such that failure occurs in the test section (reduced area as shown in Fig. 1 and Fig.2). The acceptable ratio of the areas (test section to grip section) to ensure a test section failure is dependent
20、 on the specimengripping method.Threaded end specimens may prove difficult to align and failure often initiates at these stress concentrations whentesting in the life regime of interest in this practice. A caveat is given regarding the gage section with sharp edges (that is, squareor rectangular cro
21、ss section) since these are inherent weaknesses because the slip of the grains at sharp edges is not confined byneighboring grains on two sides. Because of this, a circular cross section may be preferred if material form lends itself to thisconfiguration. The size of the gripped end relative to the
22、gage section, and the blend radius from gage section into the grip section,may cause premature failure particularly if fretting occurs in the grip section or if the radius is too small. Readers are referred toRef (1) should this occur.5.1.2 For the purpose of calculating the force to be applied to o
23、btain the required stress, the dimensions from which the areais calculated should be measured to the nearest 0.001 in. (0.03 mm) for dimensions equal to or greater than 0.200 in. (5.08 mm)and to the nearest 0.0005 in. (0.013 mm) for dimensions less than 0.200 in. (5.08 mm). Surfaces intended to be p
24、arallel and straightshould be in a manner consistent with 8.2.NOTE 2Measurements of dimensions presume smooth surface finishes for the specimens. In the case of surfaces that are not smooth, due to the factthat some surface treatment or condition is being studied, the dimensions should be measured a
25、s above and the average, maximum, and minimum valuesreported.5.2 Specimen Dimensions:5.2.1 Circular Cross SectionsSpecimens with circular cross sections may be either of two types:5.2.1.1 Specimens with tangentially blended fillets between the test section and the ends (Fig. 1)The diameter of the te
26、stsection should preferably be between 0.200 in. (5.08 mm) and 1.000 in. (25.4 mm). To ensure test section failure, the gripcross-sectional area should be at least 1.5 times but, preferably for most materials and specimens, at least four times the test sectionarea. The blending fillet radius should
27、be at least eight times the test section diameter to minimize the theoretical stressconcentration factor, Kt of the specimen. The test section length should be approximately two to three times the test sectiondiameter. For tests run in compression, the length of the test section should be approximat
28、ely two times the test section diameterto minimize buckling.5.2.1.2 Specimens with a continuous radius between ends (Fig. 3)The radius of curvature should be no less than eight timesthe minimum diameter of the test section to minimize Kt. The reduced section length should be greater than three times
29、 theminimum test section diameter. Otherwise, the same dimensional relationships should apply, as in the case of the specimensdescribed in 5.2.1.1.5.2.2 Rectangular Cross SectionsSpecimens with rectangular cross sections may be made from sheet or plate material andmay have a reduced test cross secti
30、on along one dimension, generally the width, or they may be made from material requiringdimensional reductions in both width and thickness. In view of this, no maximum ratio of area (grip to test section) should apply.The value of 1.5 given in 5.2.1.1 may be considered as a guideline. Otherwise, the
31、 sections may be either of two types:5.2.2.1 Specimens with tangentially blended fillets between the uniform test section and the ends (Fig. 4)The radius of theblending fillets should be at least eight times the specimen test section width to minimize Kt of the specimen. The ratio of specimentest se
32、ction width to thickness should be between two and six, and the reduced area should preferably be between 0.030 in.2 (19.4mm2) and 1.000 in.2 (645 mm2), except in extreme cases where the necessity of sampling a product with an unchanged surfaceFIG. 1 Specimens with Tangentially Blending Fillets Betw
33、een the Test Section and the EndsE466 152makes the above restrictions impractical. The test section length should be approximately two to three times the test section widthof the specimen. For specimens that are less than 0.100 in. (2.54 mm) thick, special precautions are necessary particularly inre
34、versed loading, such as R = 1. For example, specimen alignment is of utmost importance and the procedure outlined in PracticeE606E606/E606M would be advantageous. Also, Refs (2-5), although they pertain to strain-controlled testing, may prove ofinterest since they deal with sheet specimens approxima
35、tely 0.05 in. (1.25 mm) thick.5.2.2.2 Specimens with continuous radius between ends (Fig. 2)The same restrictions should apply in the case of this type ofspecimen as for the specimen described in 5.2.1.2.The area restrictions should be the same as for the specimen described in 5.2.2.1.5.2.3 Notched
36、SpecimensIn view of the specialized nature of the test programs involving notched specimens, no restrictionsare placed on the design of the notched specimen, other than that it must be consistent with the objectives of the program. Also,specific notched geometry, notch tip radius, information on the
37、 associated Kt for the notch, and the method and source of itsdetermination should be reported.6. Specimen Preparation6.1 The condition of the test specimen and the method of specimen preparation are of the utmost importance. Improper methodsof preparation can greatly bias the test results. In view
38、of this fact, the method of preparation should be agreed upon prior to thebeginning of the test program by both the originator and the user of the fatigue data to be generated. Since specimen preparationcan strongly influence the resulting fatigue data, the application or end use of that data, or bo
39、th, should be considered whenselecting the method of preparation. Appendix X1 presents an example of a machining procedure that has been employed on somemetals in an attempt to minimize the variability of machining and heat treatment upon fatigue life.6.2 Once a technique has been established and ap
40、proved for a specific material and test specimen configuration, change shouldnot be made because of potential bias that may be introduced by the changed technique. Regardless of the machining, grinding,or polishing method used, the final metal removal should be in a direction approximately parallel
41、to the long axis of the specimen.This entire procedure should be clearly explained in the reporting since it is known to influence fatigue behavior in the long liferegime.FIG. 2 Specimens with Continuous Radius Between EndsFIG. 3 Specimens with a Continuous Radius Between EndsFIG. 4 Specimens with T
42、angentially Blending Fillets Between the Uniform Test Section and the EndsE466 1536.3 The effects to be most avoided are fillet undercutting and residual stresses introduced by specimen machining practices. Oneexception may be where these parameters are under study. Fillet undercutting can be readil
43、y determined by inspection. Assurancethat surface residual stresses are minimized can be achieved by careful control of the machining procedures. It is advisable todetermine these surface residual stresses with X-ray diffraction peak shift or similar techniques, and that the value of the surfaceresi
44、dual stress be reported along with the direction of determination (that is, longitudinal, transverse, radial, and so forth).6.4 StorageSpecimens that are subject to corrosion in room temperature air should be accordingly protected, preferably in aninert medium. The storage medium should generally be
45、 removed before testing using appropriate solvents, if necessary, withoutadverse effects upon the life of the specimens.6.5 InspectionVisual inspections with unaided eyes or with low power magnification up to 20 should be conducted on allspecimens. Obvious abnormalities, such as cracks, machining ma
46、rks, gouges, undercuts, and so forth, are not acceptable.Specimens should be cleaned prior to testing with solvent(s) non-injurious and non-detrimental to the mechanical properties of thematerial in order to remove any surface oil films, fingerprints, and so forth. Dimensional analysis and inspectio
47、n should beconducted in a manner that will not visibly mark, scratch, gouge, score, or alter the surface of the specimen.7. Equipment Characteristics7.1 Generally, the tests will be performed on one of the following types of fatigue testing machines:7.1.1 Mechanical (eccentric crank, power screws, r
48、otating masses),7.1.2 Electromechanical or magnetically driven, or7.1.3 Hydraulic or electrohydraulic.7.2 The action of the machine should be analyzed to ensure that the desired form and magnitude of loading is maintained forthe duration of the test.7.3 The test machines should have a force-monitori
49、ng system, such as a transducer mounted in series with the specimen, ormounted on the specimen itself, unless the use of such a system is impractical due to space or other limitations. The test forcesshould be monitored continuously in the early stage of the test and periodically, thereafter, to ensure that the desired force cycleis maintained. The varying stress amplitude, as determined by a suitable dynamic verification (see Practice E467), should bemaintained at all times within 2 % of the desired test value.7.4 Test FrequencyThe range of frequencies for w
