Stress Corrosion Cracking of Sensitized AISI 304 Stainless Steel in Oxygenated High Temperature Chloride Solutions Containing Cupric (Cu2+) and Lead (Ph2+) Ions

The constant extension rate tensile (CERT) technique was used to determine the effects of moderate concentrations of Cu2+ and Pb2+ on the intergranular stress corrosion cracking (IGSCC) susceptibility of sensitized AISI 304 stainless steel (SS) in oxygenated aqueous solutions containing Cl– ions at 250 C. The open circuit potential for each straining electrode was monitored as a function of time. The results indicated that both Cu2+ and Pb2+ enhance IGSCC susceptibility in high temperature (250 C) oxygenated chloride solutions. It was found that the addition of the cations increased the electrochemical potential of the steel; however, during straining, the potential dropped to more active (negative) values with time. Cupric ion exerts its most severe effect at a concentration of approximately 80 mg/L (ppm) in solution containing 0.2 mg/L of [O2] and 104.1 mg/L of chloride ion. On the other hand, Pb2+ exhibited its most severe influence at a concentration of 25 to 30 mg/L in solutions containing 0.2 to 0.5 mg/L of [O2] and 17.71 mg/L of chloride. These findings imply that the control of Pb2+ and Cu2+ is important in any procedures that are developed to minimize IGSCC of sensitized AISI 304 SS in high temperature aqueous environments.