M23C6 carbides and Cr2N nitrides in aged duplex stainless steel: A SEM, TEM and FIB tomography investigation

J-Y Maetz; T Douillard; S Cazottes; C Verdu; X Kléber

doi:10.1016/j.micron.2016.01.007

M23C6 carbides and Cr2N nitrides in aged duplex stainless steel: A SEM, TEM and FIB tomography investigation

Micron. 2016 May:84:43-53. doi: 10.1016/j.micron.2016.01.007. Epub 2016 Feb 6.

Authors

J-Y Maetz¹, T Douillard², S Cazottes², C Verdu², X Kléber²

Affiliations

¹ Université de Lyon, INSA de Lyon, MATEIS, UMR CNRS 5510, 69621 Villeurbanne Cedex, France. Electronic address: jean-yves.maetz@ubc.ca.
² Université de Lyon, INSA de Lyon, MATEIS, UMR CNRS 5510, 69621 Villeurbanne Cedex, France.

PMID: 26925831
DOI: 10.1016/j.micron.2016.01.007

Abstract

The precipitation evolution during ageing of a 2101 lean duplex stainless steel was investigated, revealing that the precipitate type and morphology depends on the nature of the grain boundary. Triangular M23C6 carbides precipitate only at γ/δ interfaces and rod-like Cr2N nitrides precipitate at both γ/δ and δ/δ interfaces. After 15min of ageing, the M23C6 size no longer evolves, whereas that of the Cr2N continues to evolve. For Cr2N, the morphology is maintained at γ/δ interfaces, whereas percolation occurs to form a continuous layer at δ/δ interfaces. By combining 2D and 3D characterisation at the nanoscale using transmission electron microscopy (TEM) and focused ion beam (FIB) tomography, a complete description of the precipitation evolution was obtained, including the composition, crystallographic structure, orientation relationship with the matrix phases, location, morphology, size and volume fraction.

Keywords: 2101 lean duplex stainless steel; Cr(2)N nitrides; FIB nanotomography; M(23)C(6) carbides; Precipitation; TEM.