Significance and Use
4.1 The 3.5 % NaCl alternate immersion procedure is a general, all-purpose procedure that produces valid comparisons for most metals, particularly when specimens are exposed at high levels of applied stress or stress intensity.
4.2 While the alternate immersion test is an accelerated test and is considered to be representative of certain natural conditions, it is not intended to predict performance in specialized chemical environments in which a different mode of cracking may be operative. For example, it does not predict the performance of aluminum alloys in highly acidic environments such as heated inhibited red fuming nitric acid (IRFNA). For such cases, the results of the alternate immersion test are of doubtful significance until a relationship has been established between it and anticipated service environments.
4.3 While this practice is applicable in some degree to all metals, it is not equally discriminative of all alloys, even within the same metal system. Consequently, information should be established to allow comparisons of performances of the alloy of interest in the alternate immersion test and in natural environments.
Scope
1.1 This practice covers procedures for making alternate immersion stress corrosion tests in 3.5 % sodium chloride (NaCl) (Note 1). It is primarily for tests of aluminum alloys (Test Method G47) and ferrous alloys, but may be used for other metals exhibiting susceptibility to chloride ions. It sets forth the environmental conditions of the test and the means for controlling them.
1.2 This practice can be used for both stressed and unstressed corrosion specimens. Historically, it has been used for stress-corrosion cracking testing, but is often used for other forms of corrosion, such as uniform, pitting, intergranular, and galvanic.
1.3 This practice is intended for alloy development and for applications where the alternate immersion test is to serve as a control test on the quality of successive lots of the same material. Therefore, strict test conditions are stipulated for maximum assurance that variations in results are attributable to variations in the material being tested.
