A methodology for fabrication of highly pitting corrosion-resistant type 304 stainless steel by plasma carburizing and post-pickling treatment

Yu Sugawara, Waka Inoue, Izumi Muto, Nobuyoshi Hara

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Low temperature plasma carburizing was performed to improve the pitting corrosion resistance of Type 304 stainless steel. The optimal composition of the plasma gas and post-treatment were then examined. Carburizing was carried out for 18 ks at 470C in H2-CH4, Ar-H2-CH4 or Ar-CH4 plasma, and carburized layers ca. 9 μm in thickness with an average ca. 1.3 mass% carbon concentration were obtained. However, it was found that Cr23C6 was precipitated in the carburized layer and intergranular corrosion occurred under anodic polarization in 0.1 M NaCl. The precipitation behavior of Cr23C6 differed according to the plasma gas composition: H2 gas was found to suppress the size of Cr23C6. No Cr23C6 was precipitated in the inner part of the carburized layer formed in the H2-CH4 plasma, and no stable pit was initiated on the inner parts of the carburized layer under anodic polarization in 0.1 M NaCl. Pickling treatment using HF-HNO3 was applied to remove the Cr-depleted zones in the outer part of the plasma carburized layer. The Type 304 stainless steel after the plasma carburizing in the H2-CH4 atmosphere and subsequent the HF-HNO3 pickling exhibited no pitting corrosion under anodic polarization even in 3 M NaCl at 25C.

Original languageEnglish
Pages (from-to)C411-C449
JournalJournal of the Electrochemical Society
Volume165
Issue number9
DOIs
Publication statusPublished - 2018

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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