On the interstitial induced lattice inhomogeneities in nitrogen-expanded austenite

Research output: Contribution to journalArticlepeer-review

Authors

  • Xiao Tao
  • Jiahui Qi
  • Mark Rainforth
  • Allan Matthews
  • Adrian Leyland

Colleges, School and Institutes

Abstract

Lattice inhomogeneities, i.e. nitrogen interstitial-induced hexagonal-close-packed martensite (HCP-εN) and shear bands, can form in face-centred cubic nitrogen-expanded austenite (FCC-γN) synthesised on Fe-Cr-Mn and Fe-Cr-Ni austenitic stainless steel (ASS) using triode-plasma nitriding (TPN). Homogenous elemental distribution between HCP-εN and FCC-γN supports the displacive shear transformation mechanism proposed for a high-Mn, low stacking fault energy ASS under nitrogen interstitial-induced deformation. While resulting from transformation-induced plasticity, HCP-εN exhibits similar lattice expansion behaviour to the parent FCC-γN. However, inhomogeneous elemental distributions in the shear bands formed in γN layers on a 400°C TPN-treated high-Ni ASS indicate local migration of substitutional elements.

Details

Original languageEnglish
Pages (from-to)146-151
JournalScripta Materialia
Volume185
Early online date3 May 2020
Publication statusPublished - Aug 2020

Keywords

  • Nitriding, Expanded austenite, Shear banding, Martensitic phase transformation, High-resolution electron microscopy (HREM)