1、Designation: E8/E8M 11E8/E8M 13 American 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 E8/E8M; the number immediately followi
2、ng the designation indicates the year oforiginal adoption or, in the case of 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.This standard has been approved
3、 for use by agencies of the Department of Defense.1. Scope*1.1 These test methods cover the tension testing of metallic materials in any form at room temperature, specifically, the methodsof determination of yield strength, yield point elongation, tensile strength, elongation, and reduction of area.
4、1.2 The gagegauge lengths for most round specimens are required to be 4D for E8 and 5D for E8M. The gagegauge length isthe most significant difference between E8 and E8M Test Specimenstest specimens. Test specimens made from powder metallurgy(P/M) materials are exempt from this requirement by indust
5、ry-wide agreement to keep the pressing of the material to a specificprojected area and density.1.3 Exceptions to the provisions of these test methods may need to be made in individual specifications or test methods for aparticular material. For examples, see Test Methods and Definitions A370 and Tes
6、t Methods B557, and B557M.1.4 Room temperature shall be considered to be 10 to 38C 50 to 100F unless otherwise specified.1.5 The values stated in SI units are to be regarded as separate from inch/pound units. The values stated in each system are notexact equivalents; therefore each system must be us
7、ed independently of the other. Combining values from the two systems mayresult in non-conformance with the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate
8、 safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A356/A356M Specification for Steel Castings, Carbon, Low Alloy, and Stainless Steel, Heavy-Walled for Steam TurbinesA370 Test Methods and Definitions for Mech
9、anical Testing of Steel ProductsB557 Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy ProductsB557M Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products (Metric)E4 Practices for Force Verification of Testing MachinesE6 Terminology Re
10、lating to Methods of Mechanical TestingE29 Practice for Using Significant Digits in Test Data to Determine Conformance with SpecificationsE83 Practice for Verification and Classification of Extensometer SystemsE345 Test Methods of Tension Testing of Metallic FoilE691 Practice for Conducting an Inter
11、laboratory Study to Determine the Precision of a Test MethodE1012 Practice for Verification of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial ForceApplicationD1566 Terminology Relating to RubberE1856 Guide for Evaluating Computerized Data Acquisition Systems Used to Acquire
12、 Data from Universal Testing Machines1 These test methods are under the jurisdiction of ASTM Committee E28 on Mechanical Testing and are the direct responsibility of Subcommittee E28.04 on UniaxialTesting.Current edition approved Dec. 1, 2011June 1, 2013. Published February 2012August 2013. Original
13、ly approved in 1924. Last previous edition approved 20092011 asE8/E8M 09.E8/E8M 11. DOI: 10.1520/E0008_E0008M-11.10.1520/E0008_E0008M-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume in
14、formation, refer to the standards Document Summary page on the ASTM website.This 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
15、 depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM Intern
16、ational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:Definitions of Terms Common to Mechanical Testing3.1.1 The definitions of terms relating to tension testing appearing in mechanical testing terms that appear in the TerminologyE
17、6 shall be considered as applying to the terms used in these test methods of tension testing. Additional terms being defined areas follows:apply to this test method.3.1.1.1 These terms include bending strain, constraint, elongation, extensometer, force, gauge length, necking, reduced section,stress-
18、strain diagram, testing machine, and modulus of elasticity.3.1.2 In addition, the following common terms from Terminology E6 are defined:3.1.3 discontinuous yieldingyielding, nin a uniaxial test, a hesitation or fluctuation of force observed at the onset of plasticdeformation, due to localized yield
19、ing. (The stress-strain curve need not appear to be discontinuous.)3.1.3.1 DiscussionThe stress-strain curve need not appear to be discontinuous.3.1.4 elongation at fracturefracture, nthe elongation measured just prior to the sudden decrease in force associated withfracture. For many materials not e
20、xhibiting a sudden decrease in force, the elongation at fracture can be taken as the strainmeasured just prior to when the force falls below 10 % of the maximum force encountered during the test.3.1.4.1 DiscussionFor many materials not exhibiting a sudden decrease in force, the elongation at fractur
21、e can be taken as the strain measured justprior to when the force falls below 10 % of the maximum force encountered during the test.3.1.5 lower yield strength, LYS FL-2in a uniaxial test, the minimum stress recorded during discontinuous yielding, ignoringtransient effects.3.1.6 reduction of area, nt
22、he difference between the original cross-sectional area of a tension test specimen and the area ofits smallest cross section.3.1.6.1 DiscussionThe reduction of area is usually expressed as a percentage of the original cross-sectional area of the specimen.3.1.6.2 DiscussionThe smallest cross section
23、may be measured at or after fracture as specified for the material under test.3.1.6.3 DiscussionThe term reduction of area when applied to metals generally means measurement after fracture; when applied to plastics andelastomers, measurement at fracture. Such interpretation is usually applicable to
24、values for reduction of area reported in theliterature when no further qualification is given. (E28.04)3.1.7 tensile strength, Su FL2,nthe maximum tensile stress that a material is capable of sustaining.3.1.7.1 DiscussionTensile strength is calculated from the maximum force during a tension test car
25、ried to rupture and the original cross-sectional areaof the specimen.3.1.8 uniform elongation, Elu, %the elongation determined at the maximum force sustained by the test piece just prior tonecking or fracture, or both.3.1.8.1 DiscussionUniform elongation includes both elastic and plastic elongation.
26、3.1.9 upper yield strength, UYS FL-2in a uniaxial test, the first stress maximum (stress at first zero slope) associated withdiscontinuous yielding at or near the onset of plastic deformation.E8/E8M 1323.1.10 yield point elongation, YPEYPE, nin a uniaxial test, the strain (expressed in percent) sepa
27、rating the stress-straincurves first point of zero slope from the point of transition from discontinuous yielding to uniform strain hardening. If thetransition occurs over a range of strain, the YPE end point is the intersection between (a) a horizontal line drawn tangent to thecurve at the last zer
28、o slope and (b) a line drawn tangent to the strain hardening portion of the stress-strain curve at the point ofinflection. If there is no point at or near the onset of yielding at which the slope reaches zero, the material has 0 % YPE.3.1.10.1 DiscussionIf the transition occurs over a range of strai
29、n, the YPE end point is the intersection between (a) a horizontal line drawn tangentto the curve at the last zero slope and (b) a line drawn tangent to the strain hardening portion of the stress-strain curve at the pointof inflection. If there is no point at or near the onset of yielding at which th
30、e slope reaches zero, the material has 0 % YPE.3.1.11 yield strength, YSorSy FL2,nthe engineering stress at which, by convention, it is considered that plastic elongationof the material has commenced.3.1.11.1 DiscussionThis stress may be specified in terms of (a) a specified deviation from a linear
31、stress-strain relationship, (b) a specified totalextension attained, or (c) maximum or minimum engineering stresses measured during discontinuous yielding.3.2 Definitions of Terms Specific to This Standard:3.2.1 referee test, ntest made to settle a disagreement as to the conformance to specified req
32、uirements, or conducted by a thirdparty to arbitrate between conflicting results. D1566, D11.084. Significance and Use4.1 Tension tests provide information on the strength and ductility of materials under uniaxial tensile stresses. This informationmay be useful in comparisons of materials, alloy dev
33、elopment, quality control, and design under certain circumstances.4.2 The results of tension tests of specimens machined to standardized dimensions from selected portions of a part or materialmay not totally represent the strength and ductility properties of the entire end product or its in-service
34、behavior in differentenvironments.4.3 These test methods are considered satisfactory for acceptance testing of commercial shipments. The test methods have beenused extensively in the trade for this purpose.5. Apparatus5.1 Testing MachinesMachines used for tension testing shall conform to the require
35、ments of Practices E4. The forces usedin determining tensile strength and yield strength shall be within the verified force application range of the testing machine asdefined in Practices E4.5.2 Gripping Devices:5.2.1 GeneralVarious types of gripping devices may be used to transmit the measured forc
36、e applied by the testing machineto the test specimens. To ensure axial tensile stress within the gagegauge length, the axis of the test specimen should coincide withthe center line of the heads of the testing machine. Any departure from this requirement may introduce bending stresses that arenot inc
37、luded in the usual stress computation (force divided by cross-sectional area).NOTE 1The effect of this eccentric force application may be illustrated by calculating the bending moment and stress thus added. For a standard12.5-mm 0.500-in. diameter specimen, the stress increase is 1.5 percentage poin
38、ts for each 0.025 mm 0.001 in. of eccentricity. This error increasesto 2.5 percentage points/ 0.025 mm 0.001 in. for a 9 mm 0.350-in. diameter specimen and to 3.2 percentage points/ 0.025 mm 0.001 in. for a 6-mm0.250-in. diameter specimen.NOTE 2Alignment methods are given in Practice E1012.5.2.2 Wed
39、ge GripsTesting machines usually are equipped with wedge grips. These wedge grips generally furnish asatisfactory means of gripping long specimens of ductile metal and flat plate test specimens such as those shown in Fig. 1. If,however, for any reason, one grip of a pair advances farther than the ot
40、her as the grips tighten, an undesirable bending stress maybe introduced. When liners are used behind the wedges, they must be of the same thickness and their faces must be flat and parallel.For best results, the wedges should be supported over their entire lengths by the heads of the testing machin
41、e. This requires thatliners of several thicknesses be available to cover the range of specimen thickness. For proper gripping, it is desirable that the entirelength of the serrated face of each wedge be in contact with the specimen. Proper alignment of wedge grips and liners is illustratedin Fig. 2.
42、 For short specimens and for specimens of many materials it is generally necessary to use machined test specimens andto use a special means of gripping to ensure that the specimens, when under load, shall be as nearly as possible in uniformlydistributed pure axial tension (see 5.2.3, 5.2.4, and 5.2.
43、5).E8/E8M 133DimensionsStandard Specimens Subsize SpecimenPlate-Type, 40 mm1.500 in. WideSheet-Type, 12.5 mm0.500 in. Wide6 mm0.250 in. Widemm in. mm in. mm in.GGage length (Note 1 and Note 2) 200.0 0.28.00 0.0150.0 0.12.000 0.00525.0 0.11.000 0.003GGauge length (Note 1 and Note 2) 200.0 0.28.00 0.0
44、150.0 0.12.000 0.00525.0 0.11.000 0.003WWidth (Note 3 and Note 4) 40.0 2.01.500 0.125, -0.25012.5 0.20.500 0.0106.0 0.10.250 0.005TThickness (Note 5) thickness of materialRRadius of fillet, min (Note 6) 25 1 12.5 0.500 6 0.250LOverall length, min (Note 2, Note 7, and Note 8) 450 18 200 8 100 4ALengt
45、h of reduced section, min 225 9 57 2.25 32 1.25BLength of grip section, min (Note 9) 75 3 50 2 30 1.25CWidth of grip section, approximate (Note 4 and Note 9) 50 2 20 0.750 10 0.375NOTE 1For the 40 mm 1.500 in. wide specimen, punch marks for measuring elongation after fracture shall be made on the fl
46、at or on the edge ofthe specimen and within the reduced section. Either a set of nine or more punch marks 25 mm 1 in. apart, or one or more pairs of punch marks 200mm 8 in. apart may be used.NOTE 2When elongation measurements of 40 mm 1.500 in. wide specimens are not required, a minimum length of re
47、duced section (A) of 75 mm2.25 in. may be used with 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 0.10, 0.05 or 0.02 mm 0.004, 0.002or 0.001 in., respectively. Also, ther
48、e may be a gradual decrease in width from the ends to the center, but the width at each end shall not be more than1 % 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 reducedsectio
49、n should be as large as the width 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 specifications. Minimum thickness of 40 mm1.500 in. wide specimens shall be 5
