American 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 ﬁxed designation E8/E8M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, theyear 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 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, themethods of determination of yield strength, yield point elongation, tensile strength, elongation, and reduction of area. 1.2 The gage lengths for most round specimens are required to be 4D for E8 and 5D for E8M. The gage length is the most signiﬁcant difference between E8 and E8M Test Specimens Test specimens made from powder metallurgy (P/M) materials are exempt from this requirement byindustry-wide agreement to keep the pressing of the material to a speciﬁc projected 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 a particular material. For examples, see Test Methods and Deﬁnitions A370 and Test Methods B557, and B557M. 1.4 Room temperature shall be considered to be 10 to 38°C [50 to 100°F] unlessotherwise 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 not exact equivalents; therefore each system must be 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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards:2 A356/A356M Speciﬁcation for Steel Castings, Carbon, Low Alloy, and Stainless Steel, Heavy-Walled for Steam Turbines
1 These test methods are underthe jurisdiction of ASTM Committee E28 on Mechanical Testing and are the direct responsibility of Subcommittee E28.04 on Uniaxial Testing. Current edition approved Dec. 1, 2011. Published February 2012. Originally approved in 1924. Last previous edition approved 2009 as E8/E8M – 09. DOI: 10.1520/E0008_E0008M-11. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTMCustomer Service at email@example.com. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website.
A370 Test Methods and Deﬁnitions 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- andMagnesium-Alloy Products (Metric) E4 Practices for Force Veriﬁcation of Testing Machines E6 Terminology Relating to Methods of Mechanical Testing E29 Practice for Using Signiﬁcant Digits in Test Data to Determine Conformance with Speciﬁcations E83 Practice for Veriﬁcation and Classiﬁcation of Extensometer Systems E345 Test Methods of Tension Testing of Metallic Foil E691 Practice for Conducting anInterlaboratory Study to Determine the Precision of a Test Method E1012 Practice for Veriﬁcation of Test Frame and Specimen Alignment Under Tensile and Compressive Axial Force Application E1856 Guide for Evaluating Computerized Data Acquisition Systems Used to Acquire Data from Universal Testing Machines 3. Terminology 3.1 Deﬁnitions—The deﬁnitions of terms relating to tension testing appearing...