ASTM B858-01

Standard Test Method for Ammonia Vapor Test for Determination Susceptibility to Stress Corrosion Cracking in Copper Alloys

This test method describes a procedure that may be used to determine the presence of residual stresses which may lead to stress corrosion cracking of wrought copper alloy products. This test method uses an ammonia atmosphere to simulate service conditions under which stress corrosion cracking may occur. 1.2 This test method is only suitable for products fabricated from copper alloys that are known to be susceptible to stress corrosion cracking in ammonia vapor atmospheres. It is intended to create an environmental condition of reproducible severity, but it is well known that the critical step in the cracking mechanism is the development of an environment in the condensate film that occurs on the surface of the test specimen, which is rich in copper complex ions. 1.3 This test method is a conversion of ISO 6957, "Copper Alloys-Ammonia Test for Stress Corrosion Resistance." 1.4 The severity of this test method depends upon the pH of the corrosive solution. In Annex A1 are given four different atmospheres to which the product may be exposed, and the appropriate pH of the solution to be used for the test, depending on the risk level associated with the intended application. 1.4.1 The appropriate pH value for the test shall be specified in the product specification, or as per established agreement between the supplier and purchaser, with respect to the alloy and its intended application. 1.5 The values stated in SI units are the standard. 1.6 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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.