Mechanistic insights into lead-accelerated stress corrosion cracking of Alloy 600

摘要

The purpose of this work is to provide insights into the lead-accelerated stress corrosion cracking mechanisms of Alloy 600 from the perspective of the electrochemical role of lead. Lead-species were electrochemically reduced at the oxide/matrix interface, which increased the dissolution rate of the alloy elements (preferentially Cr) from and oxidation of the matrix. These electrochemical processes resulted in the fast formation of defective thick oxides with a relatively lower Cr content, which provide paths for the migration of lead-species toward the interface. Finally, the mechanistic model of fast cracking by lead contamination is described.