Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
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Effect of R Phase Formation on the Mechanical Properties of 25Cr-7Ni-2Mo-4W Super Duplex Stainless Steel

25Cr-7Ni-2Mo-4W 슈퍼 2상 스테인리스강의 기계적 성질에 미치는 R상의 영향

  • 이병찬 (한국 폴리텍 VII 대학 울산캠퍼스 신소재응용과) ;
  • 강창룡 (부경대학교 금속공학과)
  • Received : 2014.05.02
  • Accepted : 2014.07.16
  • Published : 2014.08.27
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Abstract

In this study, we investigated the precipitation behavior of the R-phase precipitated at the initial stage of aging and its effects on the mechanical properties of 25%Cr-7%Ni-2%Mo-4%W super duplex stainless steel. The R-phase was mainly precipitated at the interface of ferrite/austenite phases and inside of the ferrite phase during the initial stage of aging. It was transformed into the ${\sigma}$-phase with an increase of the aging time. The ferrite phase was decomposed into a new austenite(${\gamma}_2$)phase and the ${\sigma}$-phase by an aging treatment. The R phase was an intermetallic compound showing higher molybdenum and tungsten concentrations than the matrix and also showed higher molybdenum and tungsten concentrations than the ${\sigma}$ phase. In the initial stage of aging, precipitation of the R-phase did not change the hardness, the strength and the elongation. The hardness and the strength increased upon a longer aging time, but the elongation rapidly decreased. These results show that the R-phase did not significantly affect the hardness and the strength, though it did influence the elongation.

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  1. Effect of Aging Treatment on Impact Toughness and Corrosion Resistance of Super Duplex Stainless Steel vol.25, pp.1, 2016, https://doi.org/10.1007/s11665-015-1816-3