Lead-induced stress corrosion cracking (PbSCC) initiation in alloy 690TT in caustic environment. (September 2022)

• Record Type: Journal Article
• Authors: Mazzei, G.B.; Burke, M.G.; Horner, D.A.; Scenini, F.
• Is Part Of: Corrosion science. Volume 206(2022)
• Publication Date: 2022-09
• Subjects: Ni-base alloys -- Scanning electron microscopy (SEM) -- Stress corrosion -- De-alloying -- Alkaline corrosion; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2022.110475
• Languages: English
• ISSNs: 0010-938X

Abstract

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.