Author:
Martin Ulises,Birbilis Nick,Macdonald Digby D.,Bastidas David M.
Abstract
AbstractThe pit-to-crack transition of AISI 316LN stainless steel reinforcement exposed to stress corrosion cracking (SCC) in chlorides contaminated alkaline environment, was studied by a combination of slow strain rate testing (SSRT) and electrochemical impedance spectroscopy (EIS). The phase angle shift (Δφ) obtained by EIS at low frequencies was utilized to determine the pit-to-crack transition, differentiating from crack nucleation and propagation as identified by shifts in the frequency range of phase angle (θ) peaks. The pit-to-crack transition was developed once the maximum θ value shifted from the low to high frequencies. EIS analysis was corroborated by assessment of repassivation rates and pit growth, in addition to calculating $${\Delta G}^{{\rm{\gamma }}\to {\rm{\alpha }}{\rm{\mbox{'}}}}$$
Δ
G
γ
→
α
’
. Crack nucleation at lath martensite developed transgranular SCC. Strain-induced martensitic transformation was associated with the brittle failure of AISI 316LN stainless steel, where α’–martensite phase preferentially incubated the pit, and favored crack nucleation, thus promoting pit-to-crack transition.
Publisher
Springer Science and Business Media LLC
Subject
Materials Chemistry,Materials Science (miscellaneous),Chemistry (miscellaneous),Ceramics and Composites