Features of Crevice Corrosion of Different Grades of Duplex Stainless Steels

• Published in: Key engineering materials Vol. 943; pp. 65 - 70
• Main Authors: Karasev, Vladimir, Kovalev, Pavel, Fedorov, Aleksandr Sergeevich
• Format: Journal Article
• Language: English
• Published: Zurich Trans Tech Publications Ltd 29.03.2023
• Subjects: Corrosion; Corrosion products; Corrosion rate; Corrosion resistance; Corrosion resistant alloys; Corrosion resistant steels; Crevice corrosion; Duplex stainless steels; Ferric chloride; Ferrite; High resistance; Pitting (corrosion); Stainless steel; Uniform attack (corrosion); Crevice Corrosion; Pitting; Corrosion Properties; Duplex Stainless Steel; Microstructure
• ISSN: 1013-9826; 1662-9795; 1662-9795
• DOI: 10.4028/p-7ag619

Duplex stainless steels (DSSs) are being increasingly employed in the oil and gas and chemical industries, which, despite their high alloying degree and high resistance to general corrosion, are subject to pitting and crevice corrosion. According to their resistance to pitting and crevice corrosion, steels are ranked according to the PREN. However, nowadays there are many grades of DSSs, in which the content of Cr, Mo and N varies in different quantities, therefore the selection of the grade must be carried out with great care, considering not only PREN, but also the production technology, operating conditions, and the geometry of products. The crevice corrosion behaviors of three grades of duplex stainless steels quenched from 1050, 1100 and 1200 °C were studied in FeCl3 solution at 50°C. It is shown that PREN allows to rank only different grades in terms of corrosion resistance. With a constant PREN value, but with different contents of ferrite and austenite in steel, completely different values of the corrosion rate can be obtained, therefore, PREN must be used with great care. It was found that in the studied steels, the optimal ferrite content, at which the lowest crevice corrosion rate is achieved, is at 65 vol.%.