Corrosive Resistance of Nickel Hastelloy G-35 Superalloy in Various Aggressive Media

The corrosion resistance of nickel-based Hastelloy G-35 alloy was investigated in molten chloride salts and aggressive aqueous solutions. The corrosion rates of the alloy in NaCl–KCl, 3LiCl–2KCl, AlCl3–KCl melts at 750 °C and in boiling sulfuric acid solution in the presence of iron(III) sulphate were determined. Mechanism of the corrosion depended on the oxidizing ability of the chloride melts. Intergranular corrosion dominated in the weakly oxidizing melts and general corrosion prevailed in the highly corrosive molten salts. The presence of oxygen in the system led to a significant increase in the rate of corrosion and a change in the mechanism of corrosion.