Testing Methods for Stress Corrosion Cracking

Abstract

Stress corrosion testing methods are discussed from a general point of view with an emphasis on the desirability of standardization. The usefulness of smooth, notched, or precracked specimens is compared and some results using the different types are presented. Some precautions that should be taken are described: these include avoidance of crevice corrosion, galvanic effects, or hydrogen embrittlement results. Finally, since it is possible to find some type of environment that will crack almost every engineering alloy, it is important to use realistic loading methods and test media that relate to material serviceability for a particular application. The work of ASTM Committee G-1 on Corrosion of Metals in preparing recommended practices for various test specimens such as C-ring, bent beam, tension, U-bend, and precracked specimens is summarized; as is, similar work with environments such as the boiling MgCl2 test.

Stress Corrosion Cracking of 4140 High Strength Steel in Aqueous Solutions

“…Such a surface was found to prevent failure, as is shown by data of TableI. These results confirm the observations of previous investigators(3,17) who reported beneficial effects of a decarburized surface layer on SCC of high strength steels. The results of Table I also show that cathodically charging hydrogen onto decarburized specimens results in hydrogen cracking despite a soft surface.…”