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Depassivation and repassivation of stainless steels by stepwise pH changeEmir Mujanović,
Bojan Zajec,
Andraž Legat,
Tadeja Kosec,
Janez Kovač,
Gregor Mori,
Stefan Hönig,
Gerald Zehethofer, 2020, izvirni znanstveni članek
Povzetek: Immersion tests with different stainless steels have been performed, while the pH was stepwise decreased and then increased again. During 8.5-day exposure, the depassivation and repassivation pH values as a function of pitting resistance equivalent number were determined. There is always a gap between both pH values (depassivation and repassivation), indicating that for every steel, there are conditions where an existing passive layer can be maintained but cannot be rebuilt after depassivation. In such environments, the passive layer is thicker, consisting mainly of molybdenum and iron rich oxides, while chromium is dissolved. Usually, depending on conditions, the passive layer is more chromium-rich, especially the inner layer. This is relevant, for example, for acidizing jobs in oil and gas industry, proving that repassivation after acidizing will happen promptly, when the pH is increased again.
Ključne besede: stress corrosion cracking, surface finish impact, tapered tensile specimen, autoclave, accelerated testing, light water nuclear reactor, critical threshold stress
Objavljeno v DiRROS: 30.08.2023; Ogledov: 300; Prenosov: 156
Celotno besedilo (4,01 MB)
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