SCC is not an inevitable process, and for most metals in most environments it will not occur. Therefore it can be identified the specific combinations of metal and environment that are subject to the problem. Unfortunately, of course, as time goes by we identify more and more such combinations, especially as engineers strive to use materials more efficiently by increasing working stresses and using less expensive materials.

The requirements for SCC are somewhat different for hydrogen embrittlement than for the other two mechanisms, with the only requirement being the availability of a source of hydrogen, coupled with a material that is susceptible to hydrogen. The other SCC mechanisms are rather more specific, and normally occur when the metal has a low rate of general corrosion as a result of a protective surface film, such as the protective passive oxide film that forms on stainless steel.

by Dr. R. A. Cottis, Corrosion and Protection Centre, UMIST under contract from NPL for the Department of Trade and Industry