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.
Original language | English |
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Article number | 110475 |
Journal | Corrosion Science |
Volume | 206 |
Early online date | 22 Jul 2022 |
DOIs | |
Publication status | Published - 1 Sep 2022 |