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1、Designation: E466 07Standard Practice forConducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials1This standard is issued under the fixed designation E466; the number immediately following the designation indicates the year of original adoption or, in the case of revi
2、sion, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript 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 to o
3、btain the fatigue strength of metallic materials in the fatigue regime where the strains are predominately elastic, both upon initial loading and throughout the 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 of components 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 Specimens1 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 Deformation and Fatigue Crack Formation.Current edition approved Nov. 1, 2007. Published November
7、 2007. Originally approved in 1972. Last previous edition approved in 2002 as E466 96(2002)1 . DOI: 10.1520/E0466-07.2 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 Estimating M
8、edian Fatigue Limits, ASTM STP 731, ASTM, 1981.5 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standards volume information, refer to the standards Document Summary page on the ASTM website.E467 Pract
9、ice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing SystemE468 Practice for Presentation of Constant Amplitude Fa-tigue Test Results for Metallic MaterialsE606 Practice for Strain-Controlled Fatigue TestingE739 Practice for Statistical Analysis of Linear or Linear-
10、ized Stress-Life ( S-N) and Strain-Life (e-N) Fatigue Data E1012 Practice for Verification of Test Frame and Specimen Alignment Under Tensile and Compressive Axial ForceApplicationE1823 Terminology Relating to Fatigue and Fracture Test-ing3. Terminology3.1 Definitions:3.1.1 The terms used in this pr
11、actice 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, and so forth, on the fatigue resistance of metallic materials subjected to direct stress for relativ
12、ely large numbers of cycles. The results may 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 this practice is comparable, reproducible, and correlated among labo
13、ratories, it may be advantageous to conduct a round-robin-type test program from a statisticians point of view. To do so would require the control or balance of what are often deemed nuisance variables; for example, hardness, clean-liness, grain size, composition, directionality, surface residual st
14、ress, surface finish, and so forth. Thus, when embarking on a program of this nature it is essential to define and maintain consistency a priori, as many variables as reasonably possible,Copyright. (C) ASTM International, 100 Barr Harbor Drive, PO box C-700, West Conshohocken, Pennsylvania 19428-295
15、9, United StatesCopyright by ASTM Intl (all rights reserved); Thu Sep 15 21:08:44 EDT 20111Downloaded/printed byShanghai Jiaotong University pursuant to License Agreement. No further reproductions authorized.E466 07with as much economy as prudent. All material variables, testing information, and pro
16、cedures used should be reported so that correlation and reproducibility of 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 conditions real
17、istically simulate service conditions 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 m
18、aterial is available. However, the design 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 ensu
19、re a test section failure is dependent on the specimen gripping method. Threaded end specimens may prove difficult to align and failure often initiates at these stress concentrations when testing in the life regime of interest in this practice. A caveat is given regarding the gage section with sharp
20、 edges (that is, square or rectangular cross section) since these are inherent weaknesses because the slip of the grains at sharp edges is not confined by neighboring grains on two sides. Because of this, a circular cross section may be preferred if material form lends itself to this configuration.
21、The size of the gripped end relative to the 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 to Ref (1) should this occur.5.1.2 For the purpo
22、se of calculating the force to be applied to obtain the required stress, the dimensions from which the area is 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
23、 0.200 in. (5.08 mm). Surfaces intended to be parallel and straight should be in a manner consistent with 8.2.NOTE 2Measurements of dimensions presume smooth surface fin-ishes for the specimens. In the case of surfaces that are not smooth, due to the fact that some surface treatment or condition is
24、being studied, the dimensions should be measured as above and the average, maximum, and minimum values reported.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
25、section and the ends (Fig. 1)The diameter of the test section should preferably be between 0.200 in. (5.08 mm) and 1.000 in. (25.4 mm). To ensure test section failure, the grip cross-sectional area should be at least 1.5 times but, preferably for most materials and specimens, at least four times the
26、 test section area. The blending fillet radius should be at least eight times the test section diameter to minimize the theoretical stress concentration factor, Kt of the specimen. The test section length should be approximately two to three times the test section diameter. For tests run in compress
27、ion, the length of the test section should be approximately two times the test section diameter to 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 times the minimum diameter of the test section to minimize Kt. Th
28、e reduced section length should be greater than three times the minimum test section diameter. Otherwise, the same dimensional relationships should apply, as in the case of the specimens described in 5.2.1.1.5.2.2 Rectangular Cross SectionsSpecimens with rectan-gular cross sections may be made from
29、sheet or plate material and may have a reduced test cross section along one dimen-sion, generally the width, or they may be made from material requiring dimensional 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
30、 given in 5.2.1.1 may be considered as a guideline. Otherwise, the 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 the blending fillets should be at least eight times the specimen test sectio
31、n width to minimize Kt of the specimen. The ratio of specimen test section width to thickness should be between two and six, and the reduced area should preferably be between 0.030 in.2 (19.4 mm2) and 1.000 in.2 (645 mm2), except in extreme cases where the necessity of sampling a product with an unc
32、hanged surface makes the above restrictions impractical. The test section length should be approximately two to three times the test section width of the specimen. For specimens that are less than 0.100 in. (2.54 mm) thick, special precautions are necessary particularly in reversed loading, such as
33、R = 1. For example, specimen alignment is of utmost importance andFIG. 1 Specimens with Tangentially Blending Fillets Between the Test Section and the EndsCopyright by ASTM Intl (all rights reserved); Thu Sep 15 21:08:44 EDT 20112Downloaded/printed byShanghai Jiaotong University pursuant to License
34、Agreement. No further reproductions authorized.E466 07FIG. 2 Specimens with Continuous Radius Between EndsFIG. 3 Specimens with a Continuous Radius Between EndsFIG. 4 Specimens with Tangentially Blending Fillets Between the Uniform Test Section and the Endsthe procedure outlined in Practice E606 wou
35、ld be advanta-geous. Also, Refs (2-5), although they pertain to strain-controlled testing, may prove of interest since they deal with sheet specimens approximately 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
36、 this type of specimen 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 SpecimensIn view of the specialized nature of the test programs involving notched specimens, no restric-tions are placed on the design of t
37、he 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 associated Kt for the notch, and the method and source of its determination should be reported.6. Specimen Preparation6.1 The condition
38、 of the test specimen and the method of specimen preparation are of the utmost importance. Improper methods of preparation can greatly bias the test results. In view of this fact, the method of preparation should be agreed upon prior to the beginning of the test program by both the originator and th
39、e user of the fatigue data to be generated. Since specimen preparation can strongly influence the resulting fatigue data,the application or end use of that data, or both, should be considered when selecting the method of preparation. Appen-dix X1 presents an example of a machining procedure that has
40、 been employed on some metals in an attempt to minimize the variability of machining and heat treatment upon fatigue life.6.2 Once a technique has been established and approved for a specific material and test specimen configuration, change should not be made because of potential bias that may be in
41、troduced by the changed technique. Regardless of the ma-chining, grinding, or polishing method used, the final metal removal should be in a direction approximately parallel to the long axis of the specimen. This entire procedure should be clearly explained in the reporting since it is known to influ
42、ence fatigue behavior in the long life regime.6.3 The effects to be most avoided are fillet undercutting and residual stresses introduced by specimen machining prac-tices. One exception may be where these parameters are under study. Fillet undercutting can be readily determined by inspec-tion. Assur
43、ance that surface residual stresses are minimized can be achieved by careful control of the machining procedures. It is advisable to determine these surface residual stresses with X-ray diffraction peak shift or similar techniques, and that the value of the surface residual stress be reported along
44、with the direction of determination (that is, longitudinal, transverse, radial, and so forth).Copyright by ASTM Intl (all rights reserved); Thu Sep 15 21:08:44 EDT 20113Downloaded/printed byShanghai Jiaotong University pursuant to License Agreement. No further reproductions authorized.E466 076.4 Sto
45、rageSpecimens that are subject to corrosion in room temperature air should be accordingly protected, prefer-ably in an inert medium. The storage medium should generally be removed before testing using appropriate solvents, if nec-essary, without adverse effects upon the life of the specimens.6.5 Ins
46、pectionVisual inspections with unaided eyes or with low power magnification up to 203 should be conducted on all specimens. Obvious abnormalities, such as cracks, machining marks, gouges, undercuts, and so forth, are not acceptable. Specimens should be cleaned prior to testing with solvent(s) non-in
47、jurious and non-detrimental to the mechanical properties of the material in order to remove any surface oil films, fingerprints, and so forth. Dimensional analysis and inspection should be conducted in a manner that will not visibly mark, scratch, gouge, score, or alter the surface of the specimen.7
48、. 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, rotating 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 for the durat