Effect of pH and Chloride Contents on Stress Corrosion Cracking of Austenitic Stainless Steels at Room Temperature

Abstract Constant elongation rate tests and constant load, subcritical crack growth tests were used to investigate the stress corrosion cracking (SCC) susceptibility of metastable (type 301 [UNS S30100]) and stable (type 310S [UNS S30108]) austenitic stainless steels in H2SO4/NaCl aqueous solutions at 25°C. For annealed type 301, at each pH value there was a critical concentration of Cl− ions required to initiate SCC at 25°C. Using the constant extension rate test with notched specimens, the relation between pH and [Cl−] can be expressed as for SCC immunity: pH > 6.9 log [Cl−] + 0.7 By using a sharper, fatigue precrack and a constant load, the critical concentrations of Cl− ions for SCC immunity and active dissolution to occur at 25° can be expressed as: for SCC immunity: pH > 5 log [Cl−] + 3 for active dissolution: pH < 1.6 log [Cl−] + 0.3 SCC occurred at intermediate values of pH and [Cl−]. For type 310S, constant extension rate test results were insensitive to the environment, and the constant load tes...