1、Designation:E804American Association StateHighway and Transportation Officials StandardAASHTO No.: T68An American National StandardStandard Test Methods forTension Testing of Metallic Materials1This standard is issued under the fixed designation E 8; the number immediately following the designation
2、indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies o
3、f the Department of Defense.1. Scope*1.1 These test methods cover the tension testing of metallicmaterials in any form at room temperature, specifically, themethods of determination of yield strength, yield point elon-gation, tensile strength, elongation, and reduction of area.NOTE 1A complete metri
4、c companion to Test Methods E 8 has beendeveloped, therefore, no metric equivalents are shown in these testmethods. Committee E28 was granted an exception in 1997 by theCommittee on Standards to maintain E8 and E8M as separate companionstandards rather than combining standards as recommended by the
5、Formand Style Manual.NOTE 2Gage lengths in these test methods are required to be 4D formost round specimens. Test specimens made from powder metallurgy(P/M) materials are exempt from this requirement by industry-wideagreement to keep the pressing of the material to a specific projected areaand densi
6、ty.NOTE 3Exceptions to the provisions of these test methods may needto be made in individual specifications or test methods for a particularmaterial. For examples, see Test Methods and Definitions A 370 and TestMethods B 557.NOTE 4Room temperature shall be considered to be 50 to 100Funless otherwise
7、 specified.1.2 This standard does not purport to address all 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. R
8、eferenced Documents2.1 ASTM Standards:2A 356/A 356M Specification for Steel Castings, Carbon,Low Alloy, and Stainless Steel, Heavy-Walled for SteamTurbinesA 370 Test Methods and Definitions for Mechanical Testingof Steel ProductsB 557 Test Methods of Tension Testing Wrought and CastAluminum- and Mag
9、nesium-Alloy ProductsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE8M Test Methods for Tension Testing of Metallic Mate-rials MetricE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE83
10、 Practice for Verification and Classification of Exten-sometersE 208 Test Method for Conducting Drop-Weight Test toDetermine Nil-Ductility Transition Temperature of FerriticSteelsE 345 Test Methods of Tension Testing of Metallic FoilE 691 Practice for Conducting an Interlaboratory Study toDetermine
11、the Precision of a Test MethodE 1012 Practice for Verification of Specimen AlignmentUnder Tensile Loading3. Terminology3.1 DefinitionsThe definitions of terms relating to tensiontesting appearing in Terminology E6shall be considered asapplying to the terms used in these test methods of tensiontestin
12、g. Additional terms being defined are as follows:3.1.1 discontinuous yieldingin a uniaxial test, a hesitationor fluctuation of force observed at the onset of plastic defor-mation, due to localized yielding. (The stress-strain curve neednot appear to be discontinuous.)3.1.2 lower yield strength, LYS
13、FL2in a uniaxial test,the minimum stress recorded during discontinuous yielding,ignoring transient effects.3.1.3 upper yield strength, UYS FL2 in a uniaxial test,the first stress maximum (stress at first zero slope) associatedwith discontinuous yielding at or near the onset of plasticdeformation.3.1
14、.4 yield point elongation, YPE in a uniaxial test, thestrain (expressed in percent) separating the stress-strain curvesfirst point of zero slope from the point of transition fromdiscontinuous yielding to uniform strain hardening. If the1These test methods are under the jurisdiction of ASTM Committee
15、 E28 onMechanical Testing and are the direct responsibility of Subcommittee E28.04 onUniaxial Testing.Current edition approved April 1, 2004. Published May 2004. Originallyapproved in 1924. Last previous edition appproved 2003 as E803.2Annual Book of ASTM Standards, Vol 01.02.For referenced ASTM sta
16、ndards, 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.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM Int
17、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.transition occurs over a range of strain, the YPE end point isthe intersection between (a) a horizontal line drawn tangent tothe curve at the last zero slope and ( b) a line drawn tangent tothe strain har
18、dening portion of the stress-strain curve at thepoint of inflection. If there is no point at or near the onset ofyielding at which the slope reaches zero, the material has 0 %YPE.3.1.5 uniform elongation, Elu, %the elongation deter-mined at the maximum force sustained by the test piece justprior to
19、necking or fracture, or both.3.1.5.1 DiscussionUniform elongation includes both elas-tic and plastic elongation.4. Significance and Use4.1 Tension tests provide information on the strength andductility of materials under uniaxial tensile stresses. Thisinformation may be useful in comparisons of mate
20、rials, alloydevelopment, quality control, and design under certain circum-stances.4.2 The results of tension tests of specimens machined tostandardized dimensions from selected portions of a part ormaterial may not totally represent the strength and ductilityproperties of the entire end product or i
21、ts in-service behavior indifferent environments.4.3 These test methods are considered satisfactory for ac-ceptance testing of commercial shipments. The test methodshave been used extensively in the trade for this purpose.5. Apparatus5.1 Testing MachinesMachines used for tension testingshall conform
22、to the requirements of Practices E4. The forcesused in determining tensile strength and yield strength shall bewithin the verified force application range of the testingmachine as defined in Practices E4.5.2 Gripping Devices:5.2.1 GeneralVarious types of gripping devices may beused to transmit the m
23、easured force applied by the testingmachine to the test specimens. To ensure axial tensile stresswithin the gage length, the axis of the test specimen shouldcoincide with the center line of the heads of the testingmachine. Any departure from this requirement may introducebending stresses that are no
24、t included in the usual stresscomputation (force divided by cross-sectional area).NOTE 5The effect of this eccentric force application may be illus-trated by calculating the bending moment and stress thus added. For astandard12-in. diameter specimen, the stress increase is 1.5 percentagepoints for e
25、ach 0.001 in. of eccentricity. This error increases to 2.24percentage points/0.001 in. for a 0.350-in. diameter specimen and to 3.17percentage points/0.001 in. for a 0.250-in. diameter specimen.NOTE 6Alignment methods are given in Practice E 1012.5.2.2 Wedge GripsTesting machines usually are equippe
26、dwith wedge grips. These wedge grips generally furnish asatisfactory means of gripping long specimens of ductile metaland flat plate test specimens such as those shown in Fig. 1. If,however, for any reason, one grip of a pair advances fartherthan the other as the grips tighten, an undesirable bendin
27、gstress may be introduced. When liners are used behind thewedges, they must be of the same thickness and their facesmust be flat and parallel. For best results, the wedges should besupported over their entire lengths by the heads of the testingmachine. This requires that liners of several thicknesse
28、s beavailable to cover the range of specimen thickness. For propergripping, it is desirable that the entire length of the serratedface of each wedge be in contact with the specimen. Properalignment of wedge grips and liners is illustrated in Fig. 2. Forshort specimens and for specimens of many mater
29、ials it isgenerally necessary to use machined test specimens and to usea special means of gripping to ensure that the specimens, whenunder load, shall be as nearly as possible in uniformlydistributed pure axial tension (see 5.2.3, 5.2.4, and 5.2.5).5.2.3 Grips for Threaded and Shouldered Specimens a
30、ndBrittle MaterialsA schematic diagram of a gripping devicefor threaded-end specimens is shown in Fig. 3, while Fig. 4shows a device for gripping specimens with shouldered ends.Both of these gripping devices should be attached to the headsof the testing machine through properly lubricated spherical-
31、seated bearings. The distance between spherical bearingsshould be as great as feasible.5.2.4 Grips for Sheet MaterialsThe self-adjusting gripsshown in Fig. 5 have proven satisfactory for testing sheetmaterials that cannot be tested satisfactorily in the usual type ofwedge grips.5.2.5 Grips for WireG
32、rips of either the wedge or snubbingtypes as shown in Fig. 5 and Fig. 6 or flat wedge grips may beused.5.3 Dimension-Measuring DevicesMicrometers and otherdevices used for measuring linear dimensions shall be accurateand precise to at least one half the smallest unit to which theindividual dimension
33、 is required to be measured.5.4 Extensometers Extensometers used in tension testingshall conform to the requirements of Practice E83 for theclassifications specified by the procedure section of this testmethod. Extensometers shall be used and verified to includethe strains corresponding to the yield
34、 strength and elongation atfracture (if determined).5.4.1 Extensometers with gage lengths equal to or shorterthan the nominal gage length of the specimen (dimensionshown as “G-Gage Length” in the accompanying figures) maybe used to determine the yield behavior. For specimens withouta reduced section
35、 (for example, full cross sectional areaspecimens of wire, rod, or bar), the extensometer gage lengthfor the determination of yield behavior shall not exceed 80 %of the distance between grips. For measuring elongation atfracture with an appropriate extensometer, the gage length ofthe extensometer sh
36、all be equal to the nominal gage lengthrequired for the specimen being tested.6. Test Specimens6.1 General:6.1.1 Specimen SizeTest specimens shall be either sub-stantially full size or machined, as prescribed in the productspecifications for the material being tested.6.1.2 LocationUnless otherwise s
37、pecified, the axis of thetest specimen shall be located within the parent material asfollows:6.1.2.1 At the center for products 112 in. or less in thickness,diameter, or distance between flats.E80426.1.2.2 Midway from the center to the surface for productsover 112 in. in thickness, diameter, or dist
38、ance between flats.6.1.3 Specimen MachiningImproperly prepared testspecimens often are the reason for unsatisfactory and incorrecttest results. It is important, therefore, that care be exercised inthe preparation of specimens, particularly in the machining, tomaximize precision and minimize bias in
39、test results.6.1.3.1 The reduced sections of prepared specimens shouldbe free of cold work, notches, chatter marks, grooves, gouges,burrs, rough surfaces or edges, overheating, or any othercondition which can deleteriously affect the properties to bemeasured.DimensionsStandard Specimens Subsize Spec
40、imenPlate-Type, 112-in. Wide Sheet-Type,12-in. Wide14-in. Widein. in. in.GGage length (Note 1 and Note 2) 8.006 0.01 2.0006 0.005 1.000 6 0.003WWidth (Note 3 and Note 4)112 +18 ,14 0.5006 0.010 0.250 6 0.005TThickness (Note 5) thickness of materialRRadius of fillet, min (Note 61214LOver-all length,
41、(Note 2, Note 7 and Note 8)18 8ALength of reduced section, min 9 214 114BLength of grip section, (Note 8)314CWidth of grip section, approximate (Note 4 and Note 9)23438NOTE 1For the 112-in. wide specimen, punch marks for measuring elongation after fracture shall be made on the flat or on the edge of
42、 the specimenand within the reduced section. Either a set of nine or more punch marks 1 in. apart, or one or more pairs of punch marks 8 in. apart may be used.NOTE 2When elongation measurements of 112-in. wide specimens are not required, a minimum length of reduced section (A)of214 in. may be usedwi
43、th all other dimensions similar to those of the plate-type specimen.NOTE 3For the three sizes of specimens, the ends of the reduced section shall not differ in width by more than 0.004, 0.002 or 0.001 in., respectively.Also, there may be a gradual decrease in width from the ends to the center, but t
44、he width at each end shall not be more than 0.015, 0.005, or 0.003 in.,respectively, larger than the width at the center.NOTE 4For each of the three sizes of specimens, narrower widths ( W and C) may be used when necessary. In such cases the width of the reducedsection should be as large as the widt
45、h of the material being tested permits; however, unless stated specifically, the requirements for elongation in a productspecification shall not apply when these narrower specimens are used.NOTE 5The dimension T is the thickness of the test specimen as provided for in the applicable material specifi
46、cations. Minimum thickness of 112-in.wide specimens shall be316 in. Maximum thickness of12-in. and14-in. wide specimens shall be34 in. and14 in., respectively.NOTE 6For the 112-in. wide specimen, a12-in. minimum radius at the ends of the reduced section is permitted for steel specimens under 100 000
47、psi in tensile strength when a profile cutter is used to machine the reduced section.NOTE 7The dimension shown is suggested as a minimum. In determining the minimum length, the grips must not extend in to the transition sectionbetween Dimensions A and B, see Note 9.NOTE 8To aid in obtaining axial fo
48、rce application during testing of14-in. wide specimens, the over-all length should be as large as the material willpermit, up to 8.00 in.NOTE 9It is desirable, if possible, to make the length of the grip section large enough to allow the specimen to extend into the grips a distance equalto two third
49、s or more of the length of the grips. If the thickness of12-in. wide specimens is over38 in., longer grips and correspondingly longer gripsections of the specimen may be necessary to prevent failure in the grip section.NOTE 10For the three sizes of specimens, the ends of the specimen shall be symmetrical in width with the center line of the reduced section within0.10, 0.05 and 0.005 in., respectively. However, for referee testing and when required by product specifications, the ends of the12-in. wide s
