Abstract
The resistance to stress corrosion cracking of AISI 4340 steel foil in 0.6M aqueous sodium chloride, acidified to pH 1.5 with hydrochloric acid, is greatly decreased by prior treatment of the specimens for short periods of time with aqueous and nonaqueous solutions of sulfur, organic and inorganic sulfides, sulfur dioxides, and the inorganic salts of sulfurousand sulfuric acids. It is suggested that this prior treatment produces sulfided areas which are inhibitors of the combination of atomic hydrogen into molecular hydrogen. The decreased resistance to stress corrosion cracking is thus attributed to hydrogen embrittlement. If the stress corrosion cracking test is made in 0.6M aqueous sodium chloride, adjusted to an initial pH of 8, the effect of a prior sulfiding treatment is small. The formation of such sulfided areas in practice result from the exposure of 4340 steels to industrial atmospheres which may contain hydrogen sulfide, sulfur dioxide, and elemental sulfur.