| Title |
Effects of Mn on the Pitting Corrosion Behavior of Fe-22Cr-9Ni-3Mo Duplex Stainless Steels |
| Authors |
이지원(Ji-won Lee) ; 하헌영(Heon-Young Ha) ; 김성훈(Seong Hoon Kim) ; 이태호(Tae-Ho Lee) ; 조효행(Hyo-Haeng Jo) ; 이진종(JinJong Lee) ; 강남현(Namhyun Kang) |
| DOI |
https://doi.org/10.3365/KJMM.2025.63.10.767 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Duplex stainless steel; Pitting corrosion; General corrosion; Manganese; Nonmetallic inclusion |
| Abstract |
The effects of Mn on pitting corrosion resistance for Fe-22Cr-9Ni-3Mo-(0, 2, 4)Mn (wt%) duplex
stainless steels (DSSs) were investigated, by considering the microstructural change and the Mn content in
the solid solution state. By fabricating the ingots under carefully controlled conditions and performing hot
rolling and solution treatments, three DSSs were prepared to have similar microstructural features in terms
of phase fraction, grain size, and volume fraction of nonmetallic inclusions (NMIs). The NMIs in the DSS
without Mn were found to be Cr2O3, and those in the DSSs containing Mn were (Cr,Mn)2O3. Accordingly, the
Mn content in the solid solution state and the type of NMI were considered as the primary factors affecting
pitting resistance. Potentiodynamic polarization tests in neutral NaCl solution showed that the pitting
resistance decreased as the Mn content increased. After the polarization tests, it was found that the
(Cr,Mn)2O3 in the DSSs containing Mn acted as pitting initiation sites, whereas Cr2O3 in the DSS without
Mn remained uncorroded. In addition, the critical dissolution rate of the DSSs measured in strongly acidic
HCl solution increased with increasing Mn content, suggesting that the pit propagation rate was accelerated
by Mn addition. In conclusion, the Mn addition to DSSs reduced pitting resistance by providing more pit
initiation sites and also increasing the pit propagation rate. |