Investigation on the precipitation and corrosion behaviour of 19% Cr economical duplex stainless steel with Mn addition by aging at 800°C

ABSTRACT

The precipitation and corrosion behaviour of Fe–19Cr–1.6Ni–0.9Mo–0.2N–xMn duplex stainless steel was investigated aging at 800°C. With more Mn addition, the precipitation changed from χ-phase to σ-phase by prolonging aging time to 54 h, and the accelerating of aging induced σ-phase precipitate is mainly due to its partition by Mn. The addition of Mn from 3.6 to 5.5 wt-% decreased pitting corrosion resistance due to its detrimental effect on pitting resistance equivalent numbers, but the trend does not conform to the experimental result with Mn addition of 8.1%. The decrease in intergranular corrosion resistance mainly depends on the increase in precipitates number along δ/γ grain boundaries. It is beneficial to increase repassivation ability with higher Mn addition in early aging time,and the passivation film resistance was more sensitive to precipitate compared with more Mn addition.

KEYWORDS:

• Duplex stainless steel
• Mn addition
• sigma precipitation
• corrosion behaviour
• aging time
• ‌pitting corrosion
• ‌intergranular corrosion
• passivation ‌film

Acknowledgements

The authors acknowledge the financial support by the Fundamental Research Funds for the National Natural Science Foundation of China (grant number 51261010, No. 51861019).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors acknowledge the financial support by the Fundamental Research Funds for the National Natural Science Foundation of China (grant number 51261010, No. 51861019).