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Redefining passivity breakdown of super duplex stainless steel by electrochemical operando synchrotron near surface X-ray analyses

DOI: 10.1038/s41529-019-0084-3 DOI Help

Authors: Marie Långberg (KTH Royal Institute of Technology) , Cem Ornek (KTH Royal Institute of Technology) , Jonas Evertsson (Deutsches Elektronen-Synchrotron (DESY); Justus-Liebig-University Giessen) , Gary S. Harlow (Lund University) , Weronica Linpé (Lund University) , Lisa Rullik (Lund University) , Francesco Carlà (European Synchrotron Radiation Facility (ESRF); Diamond Light Source) , Roberto Felici (European Synchrotron Radiation Facility (ESRF)) , Eleonora Bettini (European Synchrotron Radiation Facility (ESRF)) , Ulf Kivisäkk (European Synchrotron Radiation Facility (ESRF)) , Edvin Lundgren (Lund University) , Jinshan Pan (KTH Royal Institute of Technology)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Npj Materials Degradation , VOL 3

State: Published (Approved)
Published: May 2019

Open Access Open Access

Abstract: Passivity determines corrosion resistance and stability of highly-alloyed stainless steels, and passivity breakdown is commonly believed to occur at a fixed potential due to formation and dissolution of Cr(VI) species. In this work, the study of a 25Cr–7Ni super duplex stainless steel in 1 M NaCl solution revealed that the passivity breakdown is a continuous degradation progress of the passive film over a potential range, associated with enhanced Fe dissolution before rapid Cr dissolution and removal of the oxide. The breakdown involves structural and compositional changes of the passive film and the underlying alloy surface layer, as well as selective metal dissolution depending on the anodic potential. The onset of passivity breakdown occurred at 1000 mV/Ag/AgCl, and Fe dissolved more on the ferrite than the austenite phase. With increasing potential, the passive film became thicker but less dense, while the underlying alloy surface layer became denser indicating Ni and Mo enrichment. Rapid Cr dissolution occurred at ≥1300 mV/Ag/AgCl.

Diamond Keywords: Alloys

Subject Areas: Materials, Chemistry

Facility: ESRF

Added On: 03/06/2019 12:19

Documents:
L-ngberg_et_al-2019-npj_Materials_Degradation.pdf

Discipline Tags:

Materials Engineering & Processes Physical Chemistry Chemistry Corrosion Materials Science Engineering & Technology Metallurgy

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