Electrolytic pickling of stainless steel studied by electrochemical polarisation and DC resistance measurements combined with surface analysis

K. Varga, P. Baradlai, G. Hirschberg, Z. Németh, D. Oravetz, J. Schunk, P. Tilky

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

A tightly adhering oxide scale is formed on stainless steels when they are annealed. The removal of the oxide scale and chromium-depleted subscale is one of the most important processes during the stainless steel production. Electrolytic pickling in neutral sodium sulphate is widely used for oxide scale removal. This study describes the different stages of the oxide scale removal on Polarit 725 (EN 1.4301) stainless steel in sodium sulphate solution. A mechanism of the scale dissolution is also proposed. The dissolution is proposed to proceed by the electrochemical reactions of the scale in three successive stages. At the beginning of the pickling process chromium and manganese of the outer oxide layer were preferentially dissolved. When the chromium content of the outer layer decreased, the scale was enriched of iron. The electrode potential was then increased and the scale thickness greatly reduced. Finally a steady state was obtained and a thin oxide layer, rich in iron and silicon, was left on the su rface. Silicon could not be removed by the electrolytic pickling and post-treatment in nitric-hydrofluoric acid is required.

Original languageEnglish
Pages (from-to)3859-3866
Number of pages8
JournalElectrochimica Acta
Volume46
Issue number24-25
DOIs
Publication statusPublished - Aug 15 2001

Keywords

  • Contact electric resistance
  • Electrolytic pickling
  • Stainless steel

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

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