Introduction of Cu2+ to the inside of the crevice by chelation and its effect on crevice corrosion of Type 316L stainless steel

The chelated complex of Cu ²⁺: [Cu(EDTA)] ²⁻ was used to introduce Cu ²⁺ from outside to the inside of crevice. The introduced Cu ²⁺was expected to act as an inhibitor for the crevice corrosion on stainless steels. Crevice corrosion tests confirmed the introduction of Cu ²⁺ to the inside of the crevice via electromigration of [Cu(EDTA)] ²⁻. Migrated [Cu(EDTA)] ²⁻ reacted with H ⁺ and inhibited decrease in pH inside the crevice, where Cu ²⁺ was separated from [Cu(EDTA)] ²⁻ and suppressed active dissolution of the stainless steel.