E8/E8M-21 pdf free.Standard Test Methods for Tension Testing of Metallic Materials.
4.1 Tension tesis 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 stundardi,ed dimensions from selected portions of a part or material may not totally represent the strength and ductility properties of the entire end product or its in-service behavior in different environments.
4.3 These test methods arc considered satisfactory for acceptance testing of commercial shipments. The test methods have been used estensively in the trade for this purpose.
S. Apparatus
5.1 Testing lfachi,u’s—Machines used for tension testing shall conform to the requirements of Practices E4. 11w forces used In determining tensile strength and yield strength shall he within the verified force application range of the testing machine as dcfincd in Praciiccs [4. Where verification of the testing machine speed is required. Practices E2oSK shall be used unless otherwise specified.
i.2 Gripjnig 1’ires
5.2.1 (k,,erul—Vwious 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 gauge 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 arc not included in the usual stress computation (force divided by cross-sectional area).
5.2.2 Wdge Gri,is—Tcstiiig iieadüiivs usually aic equipped with wedge grips. These wedge gnps generally furnish a satisfactory means of gripping long specimens of ductile metal and flat plate test specimens such as those shown in Fig. I. If. howeer. for any reason, one grip of a pair advances farther than the other as the grips tighten, an undesirable bending stress may be introduced. When liners are used behind the wedges. they musl he of the same thickness and their faces must be hat and parallel. For best results, the wedges should be supported over their entire lengths by the heads of the testing machine. This requires thai liners of several thicknesses be available to cover the range of specimen thickness. For proper gripping, it is desirable that the entire length of the serrated face or each wedge be in contact with the specimen. Proper alignment of wedge grips and liners is illustrated in Fig. 2. For short specimens and for specimens of many materials ii is generally necessary to use machined test specimens and to use a special means of gripping to ensure that the specimens. when under load, shall be as nearly as possible in unifonnly distributed pure axial tension (see 5.2.3. 5.2.4. and 5.2.5).
5.2.3 Grips for Thrukd and Shoukh’reI S,wein.ens and Brink Materials—A schematic diagram of a gripping device ftr threaded-end specimens is shown in Fig. 3. while Fig. 4 shows a dciic Ioi glippilig speciallells with slioukkied ends. Bolh of these gripping des ices should he altached to the heads of the testing machine through properly lubricated spherical seated bearings. The distance between spherical bearings should he as great as feasible,
5.2.4 Grips for Sheet Materials—The self-adjusting grips shown in Fig. 5 have proven satisfactory for testing sheet malerials that cannot be tested satisfactorily in the usual type of wedge grips.
5.2.5 Grips for re—Grips of either the wedge or snubbing Iypcs as showii in Fig. 5 and Fig. 6 o. flai wedge grips may be used.
5.3 l)irnension-Me’asuring lkvires—Micronieters and other devices used for measuring linear dimensions shall be accurate and precise to at least one half the smallest unit o which the individual dimension is required to be measured,
5.4 £rfrnso,,wwrs—Extensometers used in tension testing shall confonn to the requiremeilts of Practice 1*13 for the classilications specified by the procedure section of this test method. Fxiensnnieiers shall he used and verified to include the strains corresponding to the yield strength and elongation at fracture (if determined).
6.1 General:
6.1.1 Specunen Size—Test specimens shall be either substantially full size or machined, as prescribed in the product specihcations for the material being tested.
(.I.2 IAxuliI.n—Unlcss othcrwic spci6cd. thc asis of the test specinwn shall he located sithin the parent material as follows:
6.1.2.1 At the center for products 40 mum I l.fX) in.) or less in thickness. diameter, or distance beisseen flats.
6.1.2.2 Midway from the center to the surface for products oer 40 mm 11.5(X) in.I in thickness. diameter. or distamice between flats.
6.1.3 Specimen Macliming—Improperly prepared test specimens often are the reason for unsatisfactory and incorrect test results. It is important. therefore, that care be exervised in the preparation of specimens. particularly in ihc machining, to maimi,e precision and minimize bis in test results.
6. 1.3.1 The reduced section including the fillets of prepared specimens should be free of cold work, notches. chatter marks. grooves, gouges, burrs, rough surfaces or edges, overheating. or any other condition sshich can deletenously aflcct the properties to be measured.
Nn l-_-Pi,ndun IW hh.nL,n Of 54 n.gI.ee.’(I ‘P1tIflfI .ni.y pivi.ic.
significant cold work or shear burrs, or liuth. along the edges which should he removed by machining.
6.1.3.2 Within the reduced parallel section of rectangubr specimens, edges or corners should not be ground or abraded in a manner which could cause the actual cross-sectional area of the pecimcn to ho .ignificanLty diticrent from the calculated area.
6.1 .3.3 For hnnle mamenals. large radius fillets at the ends of the gauge length should be used.
6.1 .3.4 The cross-sectional area of the specimen should be smallest at the center of the reduced parallel section to ensure fracture within the gauge length. For this reason, a small taper is permitted in the reduced parallel section of each of the specimens described in the following sections.
6.1.4 .ipecisnen Surjace hni,sh —W hen matenals arc tested with surface conditions other thami as manufactured, the surface finish of LhC test specilnetas should he as provided in the applicable product specifications.E8/E8M pdf free download.