Repassivation kinetics in stress corrosion cracking — II. α-Brass in non-ammoniacal solutions

The repassivation rate kinetics of α-brass in NaNO2 solutions of various concentrations, in borate buffered Na2SO4 solutions, and in sulphide-containing Na2SO4 solutions was studied. Slow repassivation rates, with slopes of b = −0.5 in the current decay curves, were observed to be present in all the cases where SCC was found. This slow repassivation rate also proved to be a necessary, but not a sufficient condition for SCC, since the same slope was found in some cases where no SCC occurred. The use of repassivation rate techniques in the prediction of SCC susceptibility was evaluated, and the limitations of those techniques are discussed.