1、Designation: E8/E8M16aAmerican Association State Highway and Transportation Officials Standard AASHTO No.: T68 An American National Standard Standard Test Methods for Tension Testing of Metallic Materials1 This standard is issued under the fi xed designation E8/E8M; the number immediately following
2、the designation indicates the year of original adoption or, in the case of revision, 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. This standard has been approved
3、 for use by agencies of the U.S. Department of Defense. 1. Scope* 1.1 These test methods cover the tension testing of metallic materials in any form at room temperature, specifi cally, the methods of determination of yield strength, yield point elongation, tensile strength, elongation, and reduction
4、 of area. 1.2 The gauge lengths for most round specimens are re- quired to be 4D for E8 and 5D for E8M. The gauge length is the most signifi cant difference between E8 and E8M test specimens. Test specimens made from powder metallurgy (P/M) materials are exempt from this requirement by industry- wid
5、e agreement to keep the pressing of the material to a specifi c projected area and density. 1.3 Exceptions to the provisions of these test methods may need to be made in individual specifi cations or test methods for a particular material. For examples, see Test Methods and Defi nitions 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 specifi ed. 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 not exact equivalents; therefore each system must b
7、e used independently of the other. Combining values from the two systems may result 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 responsibility of the user of this standard to establish appr
8、o- priate safety and health practices and determine the applica- bility of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards:2 A356/A356M Specifi cation for Steel Castings, Carbon, Low Alloy, and Stainless Steel, Heavy-Walled for Steam Tur- bines A370 Test Methods and D
9、efi nitions for Mechanical Testing of Steel Products B557 Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products B557M Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products (Metric) E4 Practices for Force Verifi cation of Testing M
10、achines E6 Terminology Relating to Methods of Mechanical Testing E29 Practice for Using Signifi cant Digits in Test Data to Determine Conformance with Specifi cations E83 Practice for Verifi cation and Classifi cation of Exten- someter Systems E345 Test Methods of Tension Testing of Metallic Foil E6
11、91 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method E1012 Practice for Verifi cation of Testing Frame and Speci- men Alignment Under Tensile and Compressive Axial Force Application D1566 Terminology Relating to Rubber E1856 Guide for Evaluating Computerize
12、d Data Acquisition Systems Used to Acquire Data from Universal Testing Machines E2658 Practices for Verifi cation of Speed for Material Test- ing Machines 3. Terminology 3.1 Defi nitions of Terms Common to Mechanical Testing 1These test methods are under the jurisdiction of ASTM Committee E28 on Mec
13、hanical Testing and are the direct responsibility of Subcommittee E28.04 on Uniaxial Testing. Current edition approved Aug. 1, 2016. Published September 2016. Originally approved in 1924. Last previous edition approved 2016 as E8/E8M 16. DOI: 10.1520/E0008_E0008M-16A. 2For referenced ASTM standards,
14、 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. *A Summary of Changes section appears at the end of this standard Copyright ASTM Interna
15、tional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States 1 Copyright ASTM International -,-,- 3.1.1 The defi nitions of mechanical testing terms that ap- pear in the Terminology E6 apply to this test method. 3.1.1.1 These terms include bending strain, constraint, e
16、longation, extensometer, force, gauge length, necking, re- duced section, stress-strain diagram, testing machine, and modulus of elasticity. 3.1.2 In addition, the following common terms from Termi- nology E6 are defi ned: 3.1.3 discontinuous yielding, nin a uniaxial test, a hesita- tion or fl uctua
17、tion of force observed at the onset of plastic deformation, due to localized yielding. 3.1.3.1 DiscussionThe stress-strain curve need not appear to be discontinuous. 3.1.4 elongation after fracture, nthe elongation measured by fi tting the two halves of the broken specimen together. 3.1.5 elongation
18、 at fracture, nthe elongation measured just prior to the sudden decrease in force associated with fracture. 3.1.6 lower yield strength, LYS FL-2in a uniaxial test, the minimum stress recorded during discontinuous yielding, ignoring transient effects. 3.1.7 reduced parallel section, A, nthe central p
19、ortion of the specimen that has a nominally uniform cross section, with an optional small taper toward the center, that is smaller than that of the ends that are gripped, not including the fi llets. 3.1.7.1 DiscussionThis term is often called the parallel length in other standards. 3.1.7.2 DiscussionPrevious v
