Change of Solution Chemistry within Crevice in Crevice Corrosion of Stainless Steel

Abstract

The solution within the crevice of SUS 304 stainless steel during the nucleation and growth of crevice corrosion in a chloride solution were analyzed chemically. An accelerated crevice corrosion test method using activated carbon was applied to develop crevice corrosion.
The experimental results obtained are following:
(1) The current passed during the crevice corrosion test had two-stage linear relationship with the concentration of metal ions in the crevice. Selective dissolution of Cr took place.
(2) The Concentration of chloride ions had two stage linear relationship with the metal ion concentration dissolved into the crevice.
(3) pH of the solution in the crevice depended on the current passed in the crevice corrosion test.
(4) The ultra-violet absorption spectra of the solution in the crevice had a few peaks different from those of a solution prepared by mixing chlorides of Fe, Cr and Ni.
(5) The polarization curve in the pre-electrolyzed solution did not exhibit the passive region presumably due to the formation a complex of hydroxy-chloride in the crevice.