A TEM study of the crystallography of lath-shaped austenite precipitates in a duplex stainless steel

Juan Du (1) , Frédéric Mompiou (2) , Wen-Zheng Zhang (1)

1 THU - Tsinghua University [Beijing]
2 CEMES-PPM - Physique de la Plasticité et Métallurgie

The morphology of austenite (fcc) precipitates in a duplex stainless steel (DSS) is dominated by rods distributed in a ferrite (bcc) matrix. Minority of austenite precipitates also exhibits a lath shape, a common morphology in fcc to bcc transformations rather than a bcc to fcc transformation in a DSS. While the rod-shaped austenite precipitates in a DSS have been interpreted in previous investigations, precipitates with a lath shape were not well understood. This study focused on the lath-shaped austenite by using transmission electron microscopy. The habit plane of lath-shaped austenite was observed to be free of dislocations, but one array of dislocations was observed in the major side facet with a spacing of 9.6 nm and Burgers vector of [110]f/2|[010]b. These observations of crystallographic features were interpreted consistently by an O-line and good matching site analysis. Different morphologies in a DSS and similar morphologies in fcc to bcc and bcc to fcc transformations are compared and discussed.

Mots clés: Interfacial dislocation; Habit plane; Orientation relationship; Phase transformation crystallography; Precipitate morphology

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Cristallographie

Juan Du, Frédéric Mompiou, Wen-Zheng Zhang. A TEM study of the crystallography of lath-shaped austenite precipitates in a duplex stainless steel. Journal of Materials Science, 2017, 52 (19), pp.11688-11700. ⟨10.1007/s10853-017-1324-y⟩. ⟨hal-01728420⟩