Thermal ageing of ferrite in stainless steel

Pertti Nenonen

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

Abstract

The changes in the microstructure and composition of ferrite in two types of cast duplex stainless steels and in an austenitic-ferritic weld metal after long term thermal ageing has been studied using analytical transmission electron microscope (FEGTEM). A cast test steel containing Mo was investigated first as a reference material in three different conditions: as solution annealed, aged at 300oC and aged at 400oC. This investigation was carried out to gain experience of how EDS analyser and TEM can bee used to study elemental unhomogeneity, which is usually investigated with an atom probe (APFIM). The two other materials, an austenitic-ferritic weld metal and a cast duplex Ti-stabilised stainless steel used for long time at NPP operation temperature were investigated using the experience obtained with the test steel. The results showed that analytical TEM can be used to investigate elemental unhomogeneity of ferrite, but there are several important things to be taken into account when the spectra for this purpose are collected. These kind of things are, such as the thickness of the specimen, probe size, contamination rate, "elemental background" of the spectrum and possible enrichment of certain alloying elements in the surface oxide layer of the TEM-specimens. If minor elements are also analysed, it may increase the scattering of the results.
Original languageEnglish
Title of host publicationPlant Life Management
Subtitle of host publicationProgress for structural integrity
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages253-275
ISBN (Electronic)951-38-6281-X
ISBN (Print)951-38-6280-1
Publication statusPublished - 2003
MoE publication typeB3 Non-refereed article in conference proceedings
EventPlant Life Management: Progress for structural integrity - Espoo, Finland
Duration: 1 Jan 20021 Jan 2002

Publication series

SeriesVTT Symposium
Number227
ISSN0357-9387

Seminar

SeminarPlant Life Management
CountryFinland
CityEspoo
Period1/01/021/01/02

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    Nenonen, P. (2003). Thermal ageing of ferrite in stainless steel. In Plant Life Management: Progress for structural integrity (pp. 253-275). VTT Technical Research Centre of Finland. VTT Symposium, No. 227 http://www.vtt.fi/inf/pdf/symposiums/2003/S227.pdf