Growth of corrosion pits on stainless steel in chloride solution containing dilute sulphate

Effects of Copper Addition on the Passivity and Corrosion Behavior of 27Cr-7Ni Hyper Duplex Stainless Steels in Sulfuric Acid Solution

“…The potentiostatic test was measured in a deaerated 2 M H 2 SO 4 solution at 333 K with an respectively applied potential of ¹0.2 V SCE in the active region and 0.6 V SCE in the passive region of the potentiodynamic anodic polarization curves at which a meta-stable pitting can occur. 18,19) The current transients were recorded for a duration of 3600 s and 36000 s.…”

Effect of chloride and sulfate ions in simulated boiler water on pitting corrosion behavior of 13Cr steel

“…If a salt cover is formed over the pit mouth, then diffusion will be suppressed and pit growth will be inhibited. However, pit growth will not be suppressed when the cover is destroyed due to the effect of an osmotic pressure difference developing across the pit mouth cover [17,21]. In the present potentiostatic polarization tests conducted in the SO4 2--free test water, because no relatively insoluble product film was significantly formed inside the pits [19], pits growth remained stable.…”

“…Pistorious and Burstein [17] suggested that the addition of SO4 2-into a solution containing Cl -lowers the solubility of the protective salt cover (passivation film)…”

“…Pistorious and Burstein [17] suggested that the suppression of pit growth due to the addition of SO4 2-is due to the formation of a salt film with lower solubility that covers over the pit mouth and serves as a barrier to the diffusion of metal cations. On the other hand, as shown in Fig.…”

“…Pistorious and Burstein [17] suggested that at higher potentials, the pit growth is controlled by the diffusion of metal cations, which is dependent on the pit geometry. If a salt cover is formed over the pit mouth, then diffusion will be suppressed and pit growth will be inhibited.…”