Effects of the α/γ-Phase Ratio on the Corrosion Behavior of Cast Duplex Stainless Steel

Ryotaro Yamamoto, Hiroshi Yakuwa, Matsuho Miyasaka, Nobuyoshi Hara

Research output: Contribution to journalArticlepeer-review

Abstract

The effects of the α/γ-phase ratio on pitting corrosion initiation and growth in cast duplex stainless steel were studied, including the preferential dissolution of the two phases inside the pits, using pitting potential measurement and potentiostatic polarization measurement with a high concentration of chloride ions and a low pH. The initiation of pitting was not dependent on the α-phase ratio. The γ phase preferentially dissolves when a high potential in the active dissolution region is applied, and the α phase preferentially dissolves when a low potential is applied. In addition, with an increase in α-phase ratio, the potential range where the α phase preferentially dissolves enlarged toward the higher potential side. The growth rate of stable pitting increased with the α-phase ratio. Dissolution of the α phase increased with an increase in the α-phase ratio. This phenomenon is presumably caused by the decreased amount of Cr in the α phase, resulting from the increased α-phase ratio, as well as by Cr depletion around Cr nitrides.

Original languageEnglish
Pages (from-to)815-825
Number of pages11
JournalCorrosion
Volume76
Issue number9
DOIs
Publication statusPublished - 2020 Sep

Keywords

  • Corrosion rate
  • Duplex stainless steels
  • Heat treatment
  • Nitrides
  • Phase effects
  • Pitting potential

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Science(all)

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