New insights into the hardening and pitting corrosion mechanisms of thermally aged duplex stainless steel at 475 °C: A comparative study between 2205 and 2101 steels

• Published in: Journal of materials science & technology 2022-01, Vol.98, p.123-135
• Main Authors: Silva, R., Vacchi, G.S., Kugelmeier, C.L., Santos, I.G.R., Filho, A.A. Mendes, Magalhães, D.C.C., Afonso, C.R.M., Sordi, V.L., Rovere, C.A.D.
• Format: Article
• Language: English
• Subjects: Duplex stainless steel; G-phase precipitation; Hardening; Pitting corrosion; Spinodal decomposition
• ISSN: 1005-0302; 1941-1162
• DOI: 10.1016/j.jmst.2021.04.046

•Ferrite hardening is caused by α'-α phase separation.•In LDSS 2101, Cr nitrides impact pitting corrosion more than α'-evolution.•G-phase contributes to a decrease in pitting corrosion in long-term aging.•Spinodal decomposition is the main cause of the drop-in pitting corrosion of DSS 2205. In this study, the relationship between spinodal decomposition and the formation of Ni-rich clusters and G-phase in the ferrite on hardening and pitting corrosion of two thermally aged duplex stainless steels (DSSs) at 475 °C was investigated. Results indicate that, for 2205 DSS, pitting corrosion behavior is influenced by the presence and size of G-phase precipitates for longer aging times, but this contribution is masked by the advanced stage of spinodal decomposition in the ferritic structure. On the other hand, for 2101 DSS, the formation of Cr-richer nitrides impairs pitting corrosion resistance more than spinodal decomposition. [Display omitted]