Abstract
Stress-corrosion cracking facts and theories are reviewed, especially the phenomena found with stainless steels and with α-brass. Evidence is given that stress-corrosion “cracking” is not rupture of brittle metal. Rather, cracks propagate by rapid dissolution of their mechanically yielding advancing edges, while their static sides dissolve extremely slowly. Thus, crack propagation requires ductility, not brittleness, in the metal under attack.
Very rapid dissolution of yielding metal has been demonstrated. It is probably favored by (a) arrival at the dissolving surface of the dislocation pile-ups resulting from restricted slip and (b) brittle fracture of protective oxide films caused by ductile yielding of the metal beneath.
The ready supply of easily reacting material from the corrosive environment is also necessary for rapid stress-corrosion cracking.
