Lead-Induced Stress Corrosion Cracking (PbSCC) initiation in Alloy 690TT in caustic environment

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Abstract

Pb-Caustic Stress Corrosion Cracking initiation was studied on Alloy 690TT at 315°C. Advanced electron microscopy techniques revealed that cracking mainly initiated intergranularly following the oxidation of Cr-rich grain boundary carbides. This finding explains the higher resistance to crack nucleation of the as-received surfaces compared to polished ones, because the grain boundaries of the ultrafine-grained near-surface layer were not decorated with carbides. It is also proposed that dislocation entanglements, typical of a cold-worked surface, attenuated the emission of dislocations at the surface. Once initiated, cracking continued due to Pb incorporation in the oxide, which weakened the passive layer and enhanced slip dissolution.

Bibliographical metadata

Original languageEnglish
Article number110475
JournalCorrosion Science
Volume206
Early online date22 Jul 2022
DOIs
Publication statusPublished - 1 Sep 2022