Tentative Method for Mercurous Nitrate Test for Copper and Copper Alloys
|Publication Date:||1 January 1941|
This method describes the technique for conducting the mercurous nitrate testing of copper-base alloys. This test is an accelerated corrosion test for the purpose of determining in copper or copper-base alloy products or assemblies the presence of applied (external) or residual (internal) stresses, or a combination of these stresses, which might bring about failure of the material in service or storage through stress corrosion or season cracking. In this test, a suitable specimen is subjected to the effects of mercury corrosion, mercury being provided by displacement of that metal from an acidified aqueous solution of mercurous nitrate by the metal of the specimen.
NOTE 1.-The following definitions apply to this method of test:
(a) Stress Corrosion Crack.-A crack due to the simultaneous action of externally applied tensile stress and certain specific corrosive media (usually ammonia plus moisture). This type of crack occurs with little or no deformation of adjacent metal.
(b) Season Crack.-A crack due to the simultaneous action of residual stress and certain specific corrosive media (usually ammonia plus moisture). This type of crack occurs with little or no deformation of adjacent metal.
(c) Applied Stress.-An external stress due to a force from without the mass of the unit part and usually the result of assembly operations. Welding shall be considered an assembly operation.
(d) Residual Stress.-An internal stress inherent in the mass of a body in its unit form (not on assembled unit) usually as a result of cold-workind.