ASTM E8/E8M-08 pdf download.Standard Test Methods for Tension Testing of Metallic Materials.
1. 1 These test methods cover the tension testing of metallic materials in any form at room temperature, specifically, the methods 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 E 8 and 5D for E 8M. The gage length is the most significant difference between E 8 and E 8M Test Specimens Test specimens made from powder metallurgy (PIM) materials are exempt from this requirement by industry-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 he made in individual specifications or test methods for a particular material. For examples, see Test Methods and Definitions A 370 and Test Methods B 557, B 557M.
1 .4 Room temperature shall be considered to be 10 to 38°C 150 to l00°FI 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 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.
4. Significance and Use
4.1 Tension tests provide information on the strength and ductility of materials under uniaxial tensile stresses. This information may he useful in comparisons of materials, alloy development, 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 material may not totally represent the strength and ductility properties of thc entire end product or its in-service behavior in different environments.
4.3 These test methods are considered satisfactory for acceptance testing of commercial shipments. The test methods have been used extensively in the trade for this purpose.
5. Apparatus
5. 1 Testing Machines—Machines used for tension testing shall conform to the requirements of Practices E 4. The forces used in determining tensile strength and yield strength shall be within the verified force application range of the testing machine as defined in Practices E4.
5.2 Gripping Devices:
5.2.1 General—Various types of gripping devices may be used to transmit the measured force applied by the testing machine to the test specimens. To ensure axial tensile stress within the gage length. the axis of the test specimen should coincide with the center line of the heads of the testing machine. Any departure from this requirement may introduce bending stresses that are not included in the usual stress computation (force divided by cross-sectional area).ASTM E8/E8M pdf download.