Roles of different components of complex inclusion in pitting of 321 stainless steel: Induction effect of CaS and inhibition effect of TiN

Pitting behavior of 321 stainless steel (SS) in sodium chloride solution was studied by potentiostatic pulse technique triggering pits. Pure TiN inclusion and complex inclusion with core-shell structure are found in 321 SS. The former has no effect on pitting performance, while CaS in the latter is...

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Bibliographic Details
Published in:Corrosion science 2022-12, Vol.209, p.110692, Article 110692
Main Authors: Tan, Xin, Jiang, Yiming, Chen, Yiqing, Tong, Anqi, Li, Jin, Sun, Yangting
Format: Article
Language:English
Subjects:
321 stainless steel
CaS
Complex inclusion
Pitting mechanism
TiN
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Summary:Pitting behavior of 321 stainless steel (SS) in sodium chloride solution was studied by potentiostatic pulse technique triggering pits. Pure TiN inclusion and complex inclusion with core-shell structure are found in 321 SS. The former has no effect on pitting performance, while CaS in the latter is the exact inducer of pitting. Mechanism of pitting initiation and propagation induced by complex inclusions was proposed. When CaS content differs little, inhibition effect of TiN shell on pitting propagation is the main reason why a complex inclusion with higher TiN content is more resistant to pitting. •Dissolution of CaS at the boundary of complex inclusions induces pitting of 321 stainless steel.•Pitting sensitivity of inclusions with different TiN content is compared.•Pitting mechanism of 321 stainless steel in NaCl solution is proposed.•TiN shell inhibits the propagation of initial pits.•Potentiostatic pulse technique enhances pitting resistance.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2022.110692