Designation:E466−07
培训学校网站Standard Practice for
Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials1
This standard is issued under thefixed designation E466;the number immediately following the designation indicates the year of original adoption or,in the ca of revision,the year of last revision.A number in parenthes indicates the year of last reapproval.A superscript epsilon(´)indicates an editorial change since the last revision or reapproval.
1.Scope
1.1This practice covers the procedure for the performance of axial force controlled fatigue tests to obtain 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 forcing function in air at room temperature.This practice is not intended for application in axial fatigue tests of components or parts.
welkinN OTE1—The following documents,although not directly referenced in the text,are considered important enough to be listed in this practice: E739Practice for Statistical Analysis of Linear or Linearized Stress-Life(S-N)and Strain-Life(ε-N)Fatigue Data
STP566Handbook of Fatigue Testing2
STP588Manual on Statistical Planning and Analysis for Fatigue Experiments3
STP731Tables for Estimating Median Fatigue Limits4
2.Referenced Documents
2.1ASTM Standards:5
E3Guide for Preparation of Metallographic Specimens
E467Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing System
E468Practice for Prentation of Constant Amplitude Fa-tigue Test Results for Metallic Materials
E606Practice for Strain-Controlled Fatigue Testing
E739Practice for Statistical Analysis of Linear or Linearized Stress-Life(S-N)and Strain-Life(ε-N)Fatigue Data
E1012Practice for Verification of Testing Frame and Speci-men Alignment Under Tensile and Compressive Axial Force Application
E1823Terminology Relating to Fatigue and Fracture Testing 3.Terminology
3.1Definitions:
3.1.1The terms ud in this practice shall be as defined in Terminology E1823.
4.Significance and U
travel是什么意思4.1The axial force fatigue test is ud 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 relatively large numbers of cycles.The results may also be ud as a guide for the lection of metallic materials for rvice under conditions of repeated direct stress.
4.2In order to verify that such basic fatigue data generated using this practice is comparable,reproducible,and correlated among laboratories,it may be advantageous to conduct a round-robin-type test program from a statistician’s point of view.To do so would require the control or balance of what are often deemed nuisance variables;for example,hardness, cleanliness,grain size,composition,directionality,surface residual stress,surfacefinish,and so forth.Thus,when embarking on a program of this nature it is esntial to define and maintain consistency a priori,as many variables as reasonably possible,with as much economy as prudent.All material variables,testing information,and procedures ud should be reported so that correlation and reproducibility of results may be attempted in a fashion that is considered reasonably good current test practice.
4.3The results of the axial force fatigue test are suitable for application to design only when the specimen test conditions realistically simulate rvice conditions or some methodology of accounting for rvice conditions is available and clearly defined.
5.Specimen Design
5.1The type of specimen ud will depend on the objective of the test program,the type of equipment,the equipment
1This practice is under the jurisdiction of ASTM Committee E08on Fatigue and
Fracture and is the direct responsibility of Subcommittee E08.05on Cyclic
Deformation and Fatigue Crack Formation.
Current edition approved Nov.1,2007.Published November2007.Originally
approved in1972.Last previous edition approved in2002as E466–96(2002)ε1.
DOI:10.1520/E0466-07.
bending machine
2Handbook of Fatigue Testing,ASTM STP566,ASTM,1974.
3Little,R.E.,Manual on Statistical Planning and Analysis,ASTM STP588,
ASTM,1975.
4Little,R.E.,Tables for Estimating Median Fatigue Limits,ASTM STP731,
ASTM,1981.
5For referenced ASTM standards,visit the ASTM website,,or
contact ASTM Customer Service at For Annual Book of ASTM
Standards volume information,refer to the standard’s Document Summary page on
the ASTM website.
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capacity,and the form in which the material is available. However,the design should meet certain general criteria outlined below:
5.1.1The design of the specimen should be such that failure occurs in the test ction(reduced area as shown in Fig.1and Fig.2).The acceptable ratio of the areas(test ction to grip ction)to ensure a test ction failure is dependent on the specimen gripping method.Threaded end specimens may prove difficult to align and failure often initiates at the stress concentrations when testing in the life regime of interest in this practice.A caveat is given regarding the gage ction with sharp edges(that is,square or rectangular cross ction)since the are inherent weakness becau the slip of the grains at sharp edges is not confined by neighboring grains on two sides. Becau of this,a circular cross ction may be preferred if material form lends itlf to this configuration.The size of the gripped end relative to the gage ction,and the blend radius from gage ction into the grip ction,may cau premature failure particularly if fretting occurs in the grip ction or if the radius is too small.Readers are referred to Ref(1)should this occur.
5.1.2For the purpo 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 nearest0.001in.
(0.03mm)for dimensions equal to or greater than0.200in.
(5.08mm)and to the nearest0.0005in.(0.013mm)for dimensions less than0.200in.(5.08mm).Surfaces intended to be parallel and straight should be in a manner consistent with 8.2.
N OTE2—Measurements of dimensions presume smooth surfacefin-ishes for the specimens.In the ca of surfaces that are not smooth,due to the fact that some surface treatment or condition is being studied,the dimensions should be measured as above and the average,maximum,and minimum values reported.
5.2Specimen Dimensions:
5.2.1Circular Cross Sections—Specimens with circular cross ctions may be either of two types:
5.2.1.1Specimens with tangentially blendedfillets between the test ction and the ends(Fig.1)—The diameter of the test ction should preferably be between0.200in.(5.08mm)and 1.000in.(25.4mm).To ensure test ction failure,the grip cross-ctional area should be at least1.5times but,preferably for most materials and specimens,at least four times the test ction area.The blendingfillet radius should be at least eight times the test ction diameter to minimize the theoretical stress concentration factor,K t of the specimen.The test ction length should be approximately two to three times the test ction diameter.For tests run in compression,the length of the test ction should be
approximately two times the test ction diameter to minimize buckling.
5.2.1.2Specimens 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 ction to minimize K t .The reduced ction length should be greater than three times the minimum test ction diameter.Otherwi,the same dimensional relationships should apply,as in the ca of the specimens described in5.2.1.1.
5.2.2Rectangular Cross Sections—Specimens with rectan-gular cross ctions may be made from sheet or plate material and may have a reduced test cross ction along one dimension,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 ction)should apply.The value of1.5given in5.2.1.1 may be considered as a guideline.Otherwi,the ctions may be either of two types:
5.2.2.1Specimens with tangentially blendedfillets between the uniform test ction and the ends(Fig.4)—The radius of the blendingfillets should be at least eight times the specimen test ction width to minimize K t of the specimen.The ratio of specimen test ction width to thickness should be between two and six,and the reduced area should preferably be between 0.030in.2(19.4m
m2)and1.000in.2(645mm2),except in extreme cas where the necessity of sampling a product with an unchanged surface makes the above restrictions impractical. The test ction length should be approximately two to three times the test ction width of the specimen.For specimens that are less than0.100in.(2.54mm)thick,special precautions are necessary particularly in reverd loading,such as R=−1. For example,specimen alignment is of utmost importance and the procedure outlined in Practice E606would be advanta-geous.Also,Refs(2-5),although they pertain to strain-controlled testing,may prove of interest since they deal with sheet specimens approximately0.05in.(1.25mm)thick.
5.2.2.2Specimens with continuous radius between ends (Fig.2)—The same restrictions should apply in the ca of this type of specimen as for the specimen described in5.2.1.2.The area restrictions should be the same as for the specimen described in5.2.2.1.
5.2.3Notched Specimens—In view of the specialized nature of the test programs involving notched specimens,no restric-tions are 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 associated K t for the notch,and the method and source of its determination should be
reported. FIG.1Specimens with Tangentially Blending Fillets Between the Test Section and the
男士美容方法
Ends
6.Specimen Preparation
6.1The condition of the test specimen and the method of specimen preparation are of the utmost imp
中学英语作文
ortance.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 the ur of the fatigue data to be generated.Since specimen preparation can strongly influence the resulting fatigue data,the application or end u of that data,or both,should be considered when lecting the method of preparation.Appen-dix X1prents an example of a machining procedure that has been employed on some metals in an attempt to minimize the variability of machining and heat treatment upon fatigue life.6.2Once a technique has been established and approved for a specific material and test specimen configuration,change should not be made becau of potential bias that may be introduced by the changed technique.Regardless of the machining,grinding,or polishing method ud,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 influence fatigue behavior in the long life regime.
6.3The effects to be most avoided are fillet undercutting and residual stress introduced by specimen machining prac-tices.One exception may be where the parameters are under study.Fillet undercutting can be readily determined by inspec-tion.Assurance that surface residual stress are minimized can be achieved by careful control of the machining procedures.It is advisabl
e to determine the surface residual stress with X-ray diffraction peak shift or similar techniques,and that the value of the surface residual stress be reported along with the direction of determination (that is,longitudinal,transver,radial,and so forth).shallow sleep
6.4Storage—Specimens 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 necessary,without adver effects upon the life of the speci-mens.
6.5Inspection—Visual inspections with unaided eyes or with low power magnification up to 20×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-injurious 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
cinema怎么读FIG.2Specimens with Continuous Radius Between
Ends
FIG.3Specimens with a Continuous Radius Between
Ends
FIG.4Specimens with Tangentially Blending Fillets Between the Uniform Test Section and the
Ends
inspection should be conducted in a manner that will not visibly mark,scratch,gouge,score,or alter the surface of the specimen.
7.Equipment Characteristics
still7.1Generally,the tests will be performed on one of the following types of fatigue testing machines:
7.1.1Mechanical(eccentric crank,power screws,rotating mass),
7.1.2Electromechanical or magnetically driven,or
7.1.3Hydraulic or electrohydraulic.
7.2The action of the machine should be analyzed to ensure that the desired form and magnitude of loading is maintained for the duration of the test.
7.3The test machines should have a force-monitoring system,such as a transducer mounted in ries with the specimen,or mounted on the specimen itlf,unless the u of such a system is impractical due to space or other limitations. The test forces should be monitored continuously in the early stage of the test and periodically,thereafter,to ensure that the desired force cycle is maintained.The varying stress amplitude,as determined by a suitable dynamic verification (e Practice E467),should be maintained at all times within 2%of the desired test value.
7.4Test Frequency—The range of frequencies for which fatigue results may be influenced by rate effects varies from material to material.In the typical regime of10−2to10+2Hz over which most results are generated,fatigue strength is generally unaffected for most metallic engineering materials.It is beyond the scope of Practice E466to extrapolate beyond this range or to extend this assumption to other materials systems that may be viscoelastic or viscoplastic at ambient test tem-peratures and within the frequency regime mentioned.As a cautionary note,should localized yielding occur,significant specimen heating may result and affect fatigue strength.
8.Procedure
8.1Mounting the Specimen—By far the most important consideration for specimen grips is that they can be brought into good alignment consistently from specimen to specimen (e8.2).For most conventional grips,good alignment must come about from very careful attention to design detail.Every effort should be made to prevent the occurrence of misalignment,either due to twist(rotation of the grips),or to a displacement in their axes of symmetry.
8.2Alignment Verification—To minimize bending stress (strains),specimenfixtures should be aligned such that the major axis of the specimen cloly coincides with the load axis throughout each cycle.It is important that the accuracy of alignment be kept consistent from specimen to specimen.For cylindrical specimens,alignment should be checked by means of a trial test specimen with longitudinal strain gages placed at four equidistant locations around the minimum diameter.The trial test specimen should be turned about its axis,installed, and checked for each of four orientations within thefixtures.For rectangular cross ction specimens,alignment should be checked by placing longitudinal strain gages on either side of the trial specimen at the minimum width location.The trial specimen should be rotated about its longitudinal axis,installed and checked in both orientations within thefixtures.The bending stress(strains)so determined on either the cylindri-cal or rectangular
cross ction specimen should be limited to less than5%of the greater of the range,maximum or minimum stress(strains),impod during any test program. For specimens having a uniform gage length,it is advisable to place a similar t of gages at two or three axial positions within the gage ction.One t of strain gages should be placed at the center of the gage length to detect misalignment that caus relative rotation of the specimen ends about axes perpendicular to the specimen axis.The lower the bending stress(strains),the more repeatable the test results will be from specimen to specimen.This is especially important for materials with low ductility(that is,bending stress(strains) should not exceed5%of the minimum stress(strain)ampli-tude).
N OTE3—This ction refers to Type A Tests,in Practice E1012.
9.Test Termination
9.1Continue the tests until the specimen failure criterion is attained or until a predetermined number of cycles has been applied to the specimen.Failure may be defined as complete paration,as a visible crack at a specified magnification,as a crack of certain dimensions,or by some other criterion.In reporting the results,state the criterion lected for defining failure and be consistent within a given data t.
10.Report
10.1Report the following information:
10.1.1The fatigue test specimens,procedures,and results should be reported in accordance with Practice E468.
10.1.2The u of this practice is limited to metallic speci-mens tested in a suitable environment,generally atmospheric air at room temperature.Since however,the environment can greatly influence the test results,the environmental conditions, that is,temperature,relative humidity,as well as the medium, should always be periodically recorded during the test and reported.
10.1.3Generally,the fatigue tests may be carried out using
a periodic forcing function,usually sinusoidal.However, regardless of the nature of the forcing function,it should be reported(sine,ramp,saw tooth,etc.).
10.1.4When noticeable yielding occurs in the fatigue tests of unnotched specimens(for example,non-zero mean stress fatigue test)the permanent deformation of the unbroken but tested specimens(for example,percent change in cross-ction area of test ction)should be reported.
10.1.5A brief description of the fracture characteristics; results of post-test metallography or scanning election microscopy,or both;identification of fatigue mechanism;and the relative degree of transgranular and intergranular cracking would be highly
beneficial.
APPENDIX
heart(Nonmandatory Information)
X1.EXAMPLE OF MACHINING PROCEDURE
X1.1While the following procedure was developed for machining high-strength materials with minimal attendant surface damage and alteration,it can be successfully applied to materials of lower strength.As a conrvative general measure, this procedure is recommended unless:(1)the experim
ental objective is to evaluate another given surface condition or,(2) it is known that the material under evaluation is relatively innsitive to surface condition.
X1.2Procedure:
X1.2.1In thefinal stages of machining,remove material in small amounts until0.125mm(0.005in.)of excess material remains.
X1.2.2Remove the next0.1mm(0.004in.)of gage diameter by cylindrical grinding at a rate of no more than0.005 mm(0.0002in.)/pass.
X1.2.3Remove thefinal0.025mm(0.001in.)by polishing (Note X1.1)longitudinally to impart a maximum surface roughness of0.2-µm(8-µin.)R a,in the longitudinal direction.
N OTE X1.1—Extreme caution should be exercid in polishing to ensure that material is being properly removed rather than merely smeared to produce a smooth surface.This is a particular danger in soft materials wherein material can be smeared over tool marks,thereby creating a potentially undesirable influence on crack initiation during testing.
X1.2.4After polishing(e Note X1.1)all remaining grind-ing and polishing marks should be longitudin
al.No circumfer-ential machining should be evident when viewed at approxi-mately20×magnification under a light microscope.
X1.2.5Degrea thefinished specimen.
X1.2.6If heat treatment is necessary,conduct it beforefinal machining.
X1.2.7If surface obrvations are to be made,the test specimen may be electropolished in accordance with Methods E3.
X1.2.8Imprint specimen numbers on both ends of the test ction in regions of low stress,away from grip contact surfaces.
REFERENCES
(1)Worthem, D.W.,“Flat Tensile Specimen Design for Advanced
Composites,”NASA Contractor Report No.185261,NASA—Lewis Rearch Center,Cleveland,OH,November1990.
(2)Miller,G.A.,“Interlaboratory Study of Strain—Cycle Fatigue of1.2
mm—Thick Sheet Specimens,”Journal of Testing and Evaluation, JTEV A,V ol13,No.5,September1985,pp344–351.
(3)Miller,G.A.and Reemsnyder,H.S.,“Strain—Cycle Fatigue of Sheet
and Plate Steels I:Test Method Development and Data Prentation,”
High Strength Steel for Automotive U,P124,SAE Paper No.
830175,Society of Automotive Engineers,Warrendale,PA,February 1983,pp23–31.(4)Miller,G.A.and Reemsnyder,H.S.,“Strain—Cycle Fatigue of Sheet
and Plate Steels II:Some Practical Considerations in Applying Strain—Cycle Fatigue Concepts,”High Strength Steel for Automotive U,P124,SAE Paper830173,Society of Automotive Engineers, Warrendale,PA,February1983,pp33–41.
(5)Miller,G.A.and Reemsnyder,H.S.,“Strain—Cycle Fatigue of Sheet
and Plat Steels III:Tests of Notched Specimens,”High Strength Steel for Automotive U,P124,SAE Paper830176,Society of Automotive Engineers,Warrendale,PA,February1983,pp43–53.
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