Effects of structure and electrochemical properties on transgranular stress corrosion susceptibility of various copper and silver alloys and austenitic stainless steels have been examined. Results suggest that the alloys be classified in three groups according to their postulated mode of failure:
Those of the (base solvent) (noble solute) type, e.g., Cu(Au), Cu(Pt), Cu(Pd), etc., single crystals of which are generally very susceptible to stress corrosion cracking, probably on account of solute diffusion to dislocations and the accompanying local galvanic corrosion.
Those of the (base solvent) (base solute) type, e.g., Cu(Zn), etc., which are not very susceptible to stress corrosion cracking when in single crystal form and in the particular environments studied; transgranular cracking in polycrystals is believed to be mechanical in nature.
Austenitic stainless steels, transgranular stress corrosion susceptibility of which may be due to nucleation of σ phase at stacking faults, or to formation of passive surface films, or to a combination of both effects; thus, unlike (1) and (2) above, the stress corrosion behavior of these alloys may depend on stacking fault energy.
