Microstructure evolution and dislocation behaviour in high chromium, fully ferritic steels strengthened by intermetallic Laves phases

Jennifer Lopez Barrilao; Bernd Kuhn; Egbert Wessel

doi:10.1016/j.micron.2018.02.008

Microstructure evolution and dislocation behaviour in high chromium, fully ferritic steels strengthened by intermetallic Laves phases

Micron. 2018 May:108:11-18. doi: 10.1016/j.micron.2018.02.008. Epub 2018 Feb 23.

Authors

Jennifer Lopez Barrilao¹, Bernd Kuhn², Egbert Wessel²

Affiliations

¹ Forschungszentrum Jülich GmbH, Institute for Energy and Climate Research, Microstructure and Properties of Materials (IEK-2), 52428 Jülich, Germany. Electronic address: je.lopez@fz-juelich.de.
² Forschungszentrum Jülich GmbH, Institute for Energy and Climate Research, Microstructure and Properties of Materials (IEK-2), 52428 Jülich, Germany.

PMID: 29544163
DOI: 10.1016/j.micron.2018.02.008

Abstract

In the present study a stainless, high strength, ferritic (non-martensitic) steel was analysed regarding microstructure and particle evolution. The preceding hot-rolling process of the steel results in the formation of sub-grain structures, which disappear over time at high temperature. Besides that the formation of particle-free zones was observed. The pronounced formation of these zones preferentially appears close to high angle grain boundaries and is considered to be responsible for long-term material failure under creep conditions. The reasons for this are lacking particle hardening and thus a concentration and accumulation of deformation in the particle free areas close to the grain boundaries. Accordingly in-depth investigations were performed by electron microscopy to analyse dislocation behaviour and its possible effect on the mechanical response of these weak areas.

Keywords: Advanced Ultra Supercritical (AUSC) power plants; Dislocations; Ferritic steel; Intermetallic particles; Laves phase; Microstructure; Particle-free zones.