Everyone Who has run corrosion tests on the austenitic stainless steels has encountered conditions under which a specimen will corrode at a rapid rate during one or more periods of the test, but will corrode negligibly or not at all during the other periods. This behavior (which has been termed “borderline passivity”) is apparently a manifestation of the activation-passivation phenomenon common to the austenitic stainless steels. Evidently these particular corrosive conditions are not actually passivating in nature, nor do they have sufficient activating (or depassivating) action to result in consistent break-down of a passive condition, once it is attained. Consequently corrosion proceeds normally when the specimen being tested is introduced into one of these “borderline” corrosive media while the surface is active, but does not occur if the specimen surface is in the passive condition.
In the use of laboratory tests as an indication of the suitability of stainless steels...
