Nodular corrosion inside the crevice of Alloy 690 in deaerated high-temperature chloride solution

摘要

Crevice corrosion behavior of Alloy 690 in 290 ?C deaerated chloride solution was investigated using a hightemperature crevice corrosion exposure device. The results show that the oxide film enriched in Cr formed inside the crevice is thinner than that enriched in Ni formed outside the crevice. A kind of nodular corrosion occurred inside the crevice. The autocatalytic effect resulting from the limitation of metallic ions diffusion caused by the crevice geometry promoted the development of nodular corrosion. The mechanism of oxide film and nodular corrosion formation during crevice corrosion are discussed.