Abstract
Processes occurring on the surface of iron in contact with an aqueous solution of ammonium nitrate are extremely complex. They greatly depend on the electrode potential. Chemical composition, solubility, structure, thickness, adherence and compactness of solid corrosion products vary within a wide range. Intergranular stress corrosion cracking of low-carbon steel occurs within two ranges of electrode potential: approximately —0.35 to —0.1, and 0.2 to 1.6 V (S.H.E., standard hydrogen electrode).
The results strongly support the view that intergranular stress corrosion cracking of mild steel in nitrate solutions is related to passivation phenomena. Under certain conditions, the grains may already be passivated, while grain boundaries are still active.
