Abstract
The passive film stability on stainless steel can be affected by hydrogen absorption and lead to microstructure embrittlement. This work shows that the absorption of hydrogen results in surface degradation due to oxide reduction and ionic defect generation within the passive film, which decomposes and eventually vanishes. The passive film provides a barrier to entering hydrogen, but when hydrogen is formed, atomic hydrogen infuses into the lattices of the austenite and ferrite phases, causing strain evolution, as shown by synchrotron x-ray diffraction data. The vacancy concentration and hence the strains increase with increasing electrochemical cathodic polarization. Under cathodic polarization, the surface oxides are thermodynamically unstable, but the complete reduction is kinetically restrained. As a result, surface oxides remain present under excessive cathodic polarization, contesting the classical assumption that oxides are easily removed. Density-functional theory calculations have shown that the degradation of the passive film is a reduction sequence of iron and chromium oxide, which causes thinning and change of the semiconductor properties of the passive film from n-type to p-type. As a result, the surface loses its passivity after long cathodic polarization and becomes only a weak barrier to hydrogen absorption and hence hydrogen embrittlement.
Original language | English |
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Article number | 157364 |
Journal | Applied Surface Science |
Volume | 628 |
DOIs | |
Publication status | Published - 15 Aug 2023 |
Bibliographical note
Publisher Copyright:© 2023 The Author(s)
Funding
Cem Örnek is grateful for the financial support from TÜBITAK (The Scientific and Technological Research Council of Türkiye) under contract number 118C227 within the program “2232: International Fellowship for Outstanding Researchers”. Jinshan Pan and Fan Zhang are grateful for the financial support by Vinnova (Sweden's innovation agency) under contract number 2018-03267 within the program “Industrial pilot projects for neutron and photon experiments at large scale research infrastructures”. Dirk L Engelberg and Robin Kroll are grateful for the financial support of the Beijing Institute of Aeronautical Materials (China). Alfred Larsson and Gary Harlow acknowledge the Swedish Research Council for financial support within the program Röntgen-Ångström Cluster “In-situ High Energy X-ray Diffraction from Electrochemical Interfaces (HEXCHEM)” under the project no. 201506092. All authors acknowledge Diamond Light Source for time on beamline I07 under proposal SI23388. The authors are grateful to Dr Ki-Hwan Hwang, KTH Royal Institute of Technology, and Lars Hässler, KTH Royal Institute of Technology, for designing and 3D-printing the electrochemical cell used in this work. Cem Örnek is grateful for the financial support from TÜBITAK (The Scientific and Technological Research Council of Türkiye) under contract number 118C227 within the program “2232: International Fellowship for Outstanding Researchers”. Jinshan Pan and Fan Zhang are grateful for the financial support by Vinnova (Sweden’s innovation agency) under contract number 2018-03267 within the program “Industrial pilot projects for neutron and photon experiments at large scale research infrastructures”. Dirk L Engelberg and Robin Kroll are grateful for the financial support of the Beijing Institute of Aeronautical Materials (China). Alfred Larsson and Gary Harlow acknowledge the Swedish Research Council for financial support within the program Röntgen-Ångström Cluster “In-situ High Energy X-ray Diffraction from Electrochemical Interfaces (HEXCHEM)” under the project no. 201506092. All authors acknowledge Diamond Light Source for time on beamline I07 under proposal SI23388. The authors are grateful to Dr Ki-Hwan Hwang, KTH Royal Institute of Technology, and Lars Hässler, KTH Royal Institute of Technology, for designing and 3D-printing the electrochemical cell used in this work.
Funders | Funder number |
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Beijing Institute of Aeronautical Materials | |
VINNOVA | 2018-03267 |
Kungliga Tekniska Högskolan | |
Vetenskapsrådet | 201506092 |
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu | 118C227 |
Keywords
- Ab-initio density-functional theory
- Cathodic polarization
- FactSage thermodynamics
- Hydrogen embrittlement
- Passive film
- Super duplex stainless steel