Influence of chloride ion concentration and temperature on the electrochemical properties of passive films formed on a superduplex stainless steel

Souza, Elki Cristina de; Rossitti, Sérgio Mazzer; Rollo, João Manuel Domingos de Almeida

doi:10.1016/j.matchar.2009.12.004

Cited by 48 publications

(26 citation statements)

References 16 publications

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“…A PRE n above 38 is supposed to provide good resistance to marine corrosion. 5 The percentages of magnetic phases (related to the ferrite numbers) estimated by ferritoscope are compatible with the results found by quantitative metallographic analysis, even though a comparison between the volumetric percentage values of ferrite obtained by different methods is not recommended. According to the A800/A800M-91 (1997) standard, 16 the amount of ferrite in the microstructure is a function of the chemical composition of both the alloy and its thermal history.…”

Section: Resultssupporting

confidence: 62%

“…The temperature 78°C was chosen because it is above the maximum operating temperature range (60°C) 15 and below the critical temperature for pitting (80°C). 5 The electrochemical tests were performed in triplicate for the statistical relevance of the results presented. There was a small variation in the E pitt values electrochemically measured (±5 mV) for all materials investigated at different temperatures.…”

Section: Methodsmentioning

confidence: 99%

“…[1][2][3] Duplex stainless steels have been developed in response to the demand for more resistant materials in the chemical, petrochemical and oil industries. 4,5 New duplex grades with higher levels of Cr, Mo and N have been developed, as they present better localized corrosion resistance and mechanical properties. These materials have been increasingly used in aggressive environments, particularly seawater in petrochemical plants and oil and gas production systems.…”

Section: Introductionmentioning

confidence: 99%

“…The new generation of duplex stainless steels called superduplex stainless steels (PRE n = %Cr + 3.3%Mo + 16%N >40) have especially demonstrated a high performance in chloride-containing environments, e.g., seawater in off-shore platforms. 2,5 Duplex stainless steels are based on the Fe-Cr-Ni system and contain two phases in approximately equal volume fractions: ferrite (δ) and austenite (γ). In addition to Fe, Cr and Ni, they contain other chemical elements classified as either ferrite (Cr, Mo, Si) or austenite (Ni, N, C, Mn, Cu) stabilizers.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to Fe, Cr and Ni, they contain other chemical elements classified as either ferrite (Cr, Mo, Si) or austenite (Ni, N, C, Mn, Cu) stabilizers. [5][6][7][8] The advantage of the duplex alloys in media that contain chloride resides in the content of delta ferrite, which promotes combined effects due to electrochemical and mechanical factors. The relationship between both phases is usually about 50% (per volume), although it can range from 30% to 60% according to international standards, and considering variations in both chemical composition and heat treatment.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Influence of Ferrite Phase Content on the Electrochemical Properties of Duplex Stainless Steels

Souza

Rossitti²,

Fortulan

et al. 2016

Mat. Res.

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Duplex stainless steels have a large number of industrial applications and may replace high cost materials, especially in chloride-containing environments like seawater in off-shore platforms due to their high mechanical properties and good corrosion resistance. The influence of the ferrite content on the performance of duplex stainless steels in these corrosive environments is not well known. For the present paper, new superduplex stainless steels with ferrite between 30 and 60% were developed and their microstructure and corrosion resistance were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in NaCl 3.5% (wt %) at 26°C and 78°C. The results obtained at 26°C showed that the pitting potential (E pitt ) is little affected by the ferrite content, but for the materials with higher ferrite it was possible to observe an increase in the repassivation potential with a decrease in the corrosion potential and passive currents due to the presence of more resistive passive films. Tests performed at 78°C indicated a high decrease in the E pitt for all the samples, independently of the ferrite percentage, although maintaining superiority in higher ferrite content. Alloys with a 55% ferrite phase content, i.e. less dependent of Ni element, present a superior performance of corrosion resistance.

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Section: Resultssupporting

confidence: 62%

Section: Methodsmentioning

confidence: 99%