Effect of aging temperature on phase decomposition and mechanical properties in cast duplex stainless steels

The microstructure and mechanical properties in unaged and thermally aged (at 280 oC, 320 oC, 360 oC, and 400 oC to 4300 h) CF–3 and CF–8 cast duplex stainless steels (CDSS) are investigated. The unaged CF–8 steel has Cr-rich M23C6 carbides located at the δ–ferrite/γ– austenite heterophase interface...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2017-04, Vol.690
Main Authors: Mburu, Sarah, Kolli, R. Prakash, Perea, Daniel E., Schwarm, Samuel C., Eaton, Arielle, Liu, Jia, Patel, Shiv, Bartrand, Jonah, Ankem, Sreeramamurthy
Format: Article
Language:English
Subjects:
atom probe tomography
duplex stainless steel
Environmental Molecular Sciences Laboratory
G–phase
M23C6 carbide
spinodal decomposition
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Summary:The microstructure and mechanical properties in unaged and thermally aged (at 280 oC, 320 oC, 360 oC, and 400 oC to 4300 h) CF–3 and CF–8 cast duplex stainless steels (CDSS) are investigated. The unaged CF–8 steel has Cr-rich M23C6 carbides located at the δ–ferrite/γ– austenite heterophase interfaces that were not observed in the CF–3 steel and this corresponds to a difference in mechanical properties. Both unaged steels exhibit incipient spinodal decomposition into Fe-rich α–domains and Cr-rich α’–domains. During aging, spinodal decomposition progresses and the mean wavelength (MW) and mean amplitude (MA) of the compositional fluctuations increase as a function of aging temperature. Additionally, G–phase precipitates form between the spinodal decomposition domains in CF–3 at 360 oC and 400 oC and in CF–8 at 400 oC. The microstructural evolution is correlated to changes in mechanical properties.
ISSN:0921-5093
1873-4936