Effects of aging temperature on G-phase precipitation and ferrite-phase decomposition in duplex stainless steel

T. Hamaoka, A. Nomoto, K. Nishida, K. Dohi, N. Soneda

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

G-phase precipitation and ferrite-phase decomposition in a cast duplex stainless steel (DSS) aged at 623-723K for up to 8000h were investigated using atom probe tomography (APT). Large sample volume was observed in every APT experiment, which yielded significantly statistical results. The number density of G-phase precipitates tended to be high and their sizes were small at lower aging temperatures. G-phase precipitates grew during prolonged isothermal aging. The concentrations of nickel, silicon, manganese and molybdenum in G-phase precipitates tended to increase as the precipitates grew. Heterogeneous distributions of alloying elements within G-phase precipitates were observed. An interesting positional relationship of G-phase precipitates with dislocations was revealed. Regarding the ferrite-phase decomposition, local chromium concentrations in the ferrite phase varied fast at higher aging temperatures. Good correlation between the variation of local chromium concentrations and aging conditions was revealed, which indicates that the variation can be estimated for arbitrary aging conditions. Representative distances between chromium-enriched and chromium-diluted regions were long at higher aging temperatures. Time exponent of the representative distances of ferrite-phase decomposition as well as the size of G-phase precipitates increased with aging temperatures.

Original languageEnglish
Pages (from-to)4354-4375
Number of pages22
JournalPhilosophical Magazine
Volume92
Issue number34
DOIs
Publication statusPublished - 2012 Nov 27

Keywords

  • 3DAP
  • G-phase
  • aging
  • duplex stainless steel
  • microstructural characterization
  • phase decomposition

ASJC Scopus subject areas

  • Condensed Matter Physics

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