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Effect of and R Phase on the Pitting Corrosion in Super Duplex Stainless Steel

슈퍼 2상 스테인리스강의 공식에 미치는 R상의 영향

  • Lee, Byung-Chan (Dep. of Advanced Material Application, Ulsan Campus of KOREA POLYTECHNIC) ;
  • Oh, Eun-Ji (Dept. of Metallurgical Engineering, Pukyong National University) ;
  • Kang, Chang-Yong (Dept. of Metallurgical Engineering, Pukyong National University)
  • 이병찬 (한국폴리텍 VII 대학 울산캠퍼스 신소재응용과) ;
  • 오은지 (부경대학교 금속공학과) ;
  • 강창룡 (부경대학교 금속공학과)
  • Received : 2014.09.29
  • Accepted : 2014.10.13
  • Published : 2014.11.27

Abstract

In this study, we investigated the precipitation behavior of the R-phase precipitated at the initial stage of aging and its effect on the pitting corrosion of 25%Cr-7%Ni-4%Mo super duplex stainless steel. The R-phase in super duplex stainless steel was mainly precipitated at the interface of ferrite/austenite phases and inside of the ferrite phase during the initial stage of aging, and it was transformed into the ${\sigma}$-phase with an increase in aging time. The ferrite phase was decomposed into a new austenite phase and ${\sigma}$-phase. The R phase was an intermetallic compound, which represented a lower Ni and higher Mo than the matrix, and also had a higher Mo and Cr concentration than the ${\sigma}$ phase. With an increasing aging time, the pitting potential $E_p$ was increased slowly by the precipitation of the R-phase, and it was then steeply decreased by the precipitation of the ${\sigma}$-phase. The R-phase was decreased the pitting potential, but its effect was smaller than effect of ${\sigma}$-phase.

Keywords

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Cited by

  1. Effect of W Substitution on the Precipitation Behavior of χ and σ Phase in Super Duplex Stainless Steels vol.26, pp.4, 2016, https://doi.org/10.3740/MRSK.2016.26.4.200