Effects of hydrogen on the pitting susceptibility of Ni and 310 stainless steel (SS) were investigated. The results showed that hydrogen changed p-type oxide of 310 SS to n-type while it did not change the p-type oxide of Ni. Hydrogen enhanced remarkably pitting susceptibility of 310 SS. No pitting occurred for over 6 days for the samples without precharged hydrogen in 6% FeCl3 solution at room temperature. For samples precharged with very small current density of 0.1 mA/cm2 , pitting occurred within 80 minutes. The pitting even occurred within 2 minutes for the charged samples with current density of 0.5 mA/cm2. Hydrogen decreased pitting incubation time, increased pitting initiation density and growth rate. Average pit diameter D increased linearly with logarithm of immersion time...
Keywords: Hydrogen, Pitting Susceptibility, Nickel, Stainless Steel, p-type oxide, n-type oxide