Complex heterogeneous precipitation in titanium-niobium microalloyed Al-killed HSLA steels-I. (Ti,Nb)(C,N) particles

A.J. Craven, K. He, L.A.J. Garvie, T.N. Baker

Research output: Contribution to journalArticle

171 Citations (Scopus)

Abstract

Precipitation in Ti-Nb Al-killed microalloyed HSLA steels (Ti/N weight ratio from 4.4 to 1) was investigated in both the as-rolled and the normalised conditions using analytical electron microscopy including parallel electron energy loss spectroscopy (PEELS). An extensive formation of heterogeneously nucleated complex (Ti,Nb)(C,N) particles down to 10 nm in size was observed. The core of such a complex particle is based on TiN and has a spherical, cubic or cruciform shape. The N/(Ti+Nb) atomic ratio in the core is similar to the average value in the steel whereas the Nb/Ti ratio is much smaller than the average value and not proportional to it. Many of the cores have caps in the form of epitaxial overgrowths based on NbC. Their composition changes from Nb(C,N) to (Nb,Ti)C as the N/Ti ratio decreases. The formation of these complex particles and their detailed morphology are controlled by the processing conditions as well as the overall composition.
Original languageEnglish
Pages (from-to)3857-3868
Number of pages11
JournalActa Materialia
Volume48
Issue number15
DOIs
Publication statusPublished - 25 Sep 2000

Keywords

  • microstructure
  • electron energy loss spectroscopy
  • EELS
  • energy dispersive X-ray analysis
  • EDX
  • microalloyed steels
  • carbides/nitrides

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