Effect of alloy composition and temperature on corrosion behavior of stainless steels in hot alkaline solutions

Mikko Vepsäläinen, Pekka Pohjanne, Mikko Heikkilä, Carl-Gustav Berg, Jyrki Romu, Tapio Saukkonen, Hannu Hänninen, Thomas Ohligschläger, Martti Pulliainen

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    1 Citation (Scopus)


    Corrosion behavior of austenitic stainless steel UNS( 1 ) S30403, duplex stainless steels UNS S32101, UNS S32304, UNS S32205 and UNS S32507 as well as ferritic stainless steels UNS S43932 and ASTM(2) 444 was evaluated with U-bend specimens in alkaline solutions containing 500 g/l NaOH, 100 g/l NaOH + 55 g/l Na2S (hot white liquor [HWL]) and 15 g/l NaOH + 150 g/l Na2S (hot black liquor [HBL]) at temperatures of 140 and 190°C. Corrosion rates were determined from weight losses of the samples. The susceptibility to stress corrosion cracking (SCC) was characterized with optical microscopy and field emission gun scanning electron microscope (FEG-SEM). In addition, the corrosion products were analyzed with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Based on the results the highest corrosion rates were obtained in 500 g/l NaOH solution, whereas in hot black and hot white liquors the corrosion rates were significantly lower. Increase in temperature resulted in higher corrosion rates, especially in pure NaOH solutions. Molybdenum alloying enhanced corrosion particularly at 190 °C and in the presence of Na2S, whereas chromium seems to improve the corrosion resistance. Severe SCC was observed in the austenitic and ferritic stainless steels. The EDS and XRD analyses showed that different corrosion products form in sulfide containing solutions than in pure NaOH solutions. In pure NaOH solutions various oxides are formed, but in the presence of Na2S also sulfide containing corrosion products, such as iron-nickel sulfides, are formed.
    Original languageEnglish
    Title of host publicationCorrosion 2013
    Subtitle of host publicationProceedings
    PublisherNational Association of Corrosion Engineers (NACE)
    ISBN (Print)978-1-6274-8145-8
    Publication statusPublished - 2013
    MoE publication typeA4 Article in a conference publication
    EventCorrosion 2013 - Orlando, FL, United States
    Duration: 17 Mar 201321 Mar 2013


    ConferenceCorrosion 2013
    Country/TerritoryUnited States
    CityOrlando, FL


    • alkaline solution
    • corrosion rate
    • sodium hydroxide
    • sodium sulfide
    • stainless steel
    • stress corrosion cracking


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