Cathodic Protection and Hydrogen in Stress Corrosion Cracking Available to Purchase

The relationship between brittle delayed failure under stress, hydrogen permeation, and applied potential, has been examined for a high strength steel in an aerated and deaerated 3N NaCl environment. In the presence of oxygen at low cathodic potentials, no hydrogen permeation was detected and the brittle delayed failure characteristics were minimized, thus exhibiting the usual behavior associated with cathodic protection. However in the absence of oxygen, substantial hydrogen permeation and brittle delayed failure were observed at precisely the same cathodic potentials as employed in the aerated solution. Thus, a definite one-to-one correlation exists between hydrogen availability for embrittlement and stress corrosion cracking (SCC). It is concluded that the phenomenon of cathodic protection does not rule out a hydrogen embrittlement mechanism for SCC. Under anodic potentials, the relation between hydrogen permeation with pitting and brittle delayed failure was confirmed.