Effect of micro-alloy elements (Ti, Nb, Al and Ca) on corrosion resistance of 26%Cr-2%Mo stainless steel in chloride solutions
- POSCO Technical Research Labs., Pohang (Korea, Republic of)
Ferritic stainless steels have higher corrosion and stress corrosion cracking resistance in chloride environments than austenitic stainless steels. The production mat of ferritic stainless steels is lower than austenitic stainless steels. However, the application of highly alloyed ferritic stainless steels is limited due to low toughness and intergranular corrosion attack. Corrosion resistance of 26%Cr-2%Mo ferritic steels was evaluated using polarization test in 20% NaCl solution and the ferric chloride test. In addition, TEM and SEM were employed to analyze the secondary phases around the matrix where pitting corrosion occurred. In ferric chloride test the crevice corrosion resistance of non-stabilized alloy and Ca added alloy was lower than that of stabilized alloy and the crevice corrosion resistance of stabilized alloys was independent of stabilizing element such as Ti and Nb. The pitting corrosion resistance in chloride solution depended on micro-alloying elements as well as the surface treatment such as pickling and polishing. The effect of micro-alloy element and surface treatment on corrosion properties was explained with the aid of SEM observations. Among the polished alloys, the addition of Nb was the most effective for pitting corrosion resistance but the addition of Ti or Ca decreased the corrosion resistance. The pickling increased the corrosion resistance in all alloys except alloy No. 4 (Ti + Nb + Al). Pickling effectively increased corrosion resistance of the alloy containing Ti or Ca, due to removal of pit initiation sites associated with TiN inclusions or unstable phase (i.e., CaS, TiN).
- OSTI ID:
- 697035
- Report Number(s):
- CONF-990401-; TRN: IM9946%%421
- Resource Relation:
- Conference: Corrosion 1999 conference, San Antonio, TX (United States), 25 Apr 1999; Other Information: DN: 1 CD-ROM. Operating Systems: Windows 3.1, `95, `98 and NT; Macintosh; and UNIX; PBD: 1999; Related Information: Is Part Of Corrosion 99: Proceedings; PB: [3500] p.
- Country of Publication:
- United States
- Language:
- English
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