ASTM G47-2019 pdf free download

ASTM G47-2019 pdf free download.Standard Test Method for Determining Susceptibility to Stress-Corrosion Cracking of 2XXX and 7XXX Aluminum Alloy Products
1. Scope
1.1 This test method covers a uniform procedure for char- acterizing the resistance to stress-corrosion cracking (SCC) of high-strength aluminum alloy wrought products for the guid- ance ofthose who perform stress-corrosion tests, for those who prepare stress-corrosion specifications, and for materials engi- neers. 1.2 This test method covers method of sampling, type of specimen, specimen preparation, test environment, and method ofexposure for determining the susceptibility to SCC of2XXX (with 1.8 to 7.0 % copper) and 7XXX (with 0.4 to 2.8 % copper) aluminum alloy products, particularly when stressed in the short-transverse direction relative to the grain structure. 1.3 The values stated in SI units are to be regarded as standard. The inch-pound units in parentheses are provided for information. 1.4 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
5. Interferences
5.1 A disadvantage of the 3.5 % NaCl solution alternate immersion test is that severe pitting may develop in the specimens. Such pitting in tension specimens with relatively small cross section can markedly reduce the effective cross- sectional area and produce a net section stress greater than the nominal gross section stress, resulting in either: (1) fracture by mechanical overload of a material that is not susceptible to SCC; or (2) SCC of a material at an actual stress higher than the intended nominal test stress. The occurrence of either of these phenomena might then interfere with a valid evaluation of materials with relatively high resistance to stress corrosion.
6. Test Specimen
6.1 Type and Size—No single configuration oftest specimen is applicable for the many complex shapes and sizes of products that must be evaluated. A tension specimen is pre- ferred because it more consistently provides definite evidence of cracking and should be used whenever the size and shape of the product permits; it also provides a more severe test. 6.1.1 Tension Specimen—The diameter of the reduced sec- tion shall be 3.17 6 0.03 mm (0.125 6 0.001 in.). 6.1.2 C-Ring (see Practices G38)—The use of C-rings permits short-transverse tests to be made of sections that are too thin or complex for practical tests with a tension specimen. C-rings may be of various sizes as required for the product to be tested, but in no case less than 15.88 6 0.05 mm (0.625 6 0.002 in.) in outside diameter. The ratio of diameter to wall thickness shall be kept in the range from 11:1 to 16:1.6.2 Stressing Direction: 6.2.1 Short-Transverse Tests: 6.2.1.1 For specified material thicknesses of 38.10 mm (1.500 in.) and over, the tension specimen shall be used. 6.2.1.2 For specified material thicknesses of 17.78 through 38.08 mm (0.700 through 1.499 in.), a C-ring shall be used. A tension specimen may be used if consistent with the provisions of Practice G49. 6.2.2 For other stress directions in materials of 6.35 mm (0.250 in.) and over, the tension specimen shall be used. 6.3 Surface Preparation—Test specimens shall be degreased prior to exposure.
7. Sampling and Number of Tests
7.1 Unless otherwise specified, tests shall be performed in the short-transverse direction; the intention is to orient the specimen so that the applied tensile stress is perpendicular to the metal flow lines and in the short-transverse direction relative to the grain structure. In rolled or extruded sections that are approximately round or square, there is no true short-transverse direction because in a transverse plane the grains tend to be equiaxial; and, in such cases, the stress should be directed simply in the transverse direction. If, in certain unusual cases, the grain structure is or tends to be equiaxial also in the longitudinal direction, the stress shall be applied in a direction parallel to the smallest dimension of the product.