University of Oulu

Airaksinen, S., Tuovinen, T., Vuolio, T., Laukka, A., Heikkinen, E., Riekki, E. and Fabritius, T. (2022), Oxide Scale Formation of EN 1.4622 and EN 1.4828 Stainless Steels during Annealing and Descaling Behavior in Neutral Electrolytic Pickling. steel research int., 93: 2100366.

Oxide scale formation of EN 1.4622 and EN 1.4828 stainless steels during annealing and descaling behavior in neutral electrolytic pickling

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Author: Airaksinen, Susanna1; Tuovinen, Teemu2; Vuolio, Tero3;
Organizations: 1Process Metallurgy Research Unit, University of Oulu, P.O. Box 4300, Oulu, 90014 Finland
2Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 4300, Oulu, 90014 Finland
3Environmental and Chemical Engineering Research Unit, University of Oulu, Oulu, Finland
4Tornio R&D Center, Outokumpu Stainless Oy, Tornio, 95490 Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.5 MB)
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Language: English
Published: John Wiley & Sons, 2021
Publish Date: 2021-12-20


Oxide scale formation during short-term annealing and electrolytic pickling behavior of ferritic EN 1.4622 and austenitic EN 1.4828 stainless steels are investigated. The annealing is performed at temperatures between 1000 and 1100 °C for ferritic and 1100 and 1200 °C for austenitic steel grade under humid atmospheres in simulated industrial process. Neutral electrolytic pickling, also referred to as neutral electrochemical pickling or the Ruthner Neolyte Process, is performed in Na₂SO₄ electrolyte, and pickling efficiency is evaluated visually and by image analysis of pickled surfaces. The results show that annealing conditions have a more impactful effect on the structure and the composition of the resulting oxide in the austenitic grade within the studied condition range. The thicknesses of the ferritic scales are mainly less than 0.4 μm, while almost all austenitic scales are thicker than it. In addition, the amount of silicon oxide formation inside the steel matrix of the austenitic and ferritic grades is highly different. Longer exposure times and higher temperatures promote scale growth during annealing, resulting in inefficient electrolytic pickling for the ferritic grade. For the austenitic grade, almost all steel surfaces are still covered with oxide scale after electrolytic pickling.

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Series: Steel research international
ISSN: 1611-3683
ISSN-E: 1869-344X
ISSN-L: 1611-3683
Volume: 93
Issue: 1
Article number: 2100366
DOI: 10.1002/srin.202100366
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
Funding: This research was conducted with a financial grant from the Towards Carbon Neutral Metals project (TOCANEM).
Copyright information: © 2021 The Authors. Steel Research International published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.