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Atomic scale identification of nano-sized precipitates of Ta/Ti-added RAFM steel and its superior creep strength

Title
Atomic scale identification of nano-sized precipitates of Ta/Ti-added RAFM steel and its superior creep strength
Authors
Jun, Sun-YoungKim, Tae-YeongIm, So-YoungKim, Chi-WonLee, Bong HoMoon, JoonohLee, Chang-HoonHong, Hyun-Uk
Issue Date
2020-11
Citation
Materials Characterization, 169, 110596
Type
Article
Article Type
Article
Author Keywords
Atom probe tomographyCreepMicrostructureReduced activation ferritic/martensitic steelsTi
Keywords
CreepSteel metallographyAtom probe tomographyCreep rupture lifeDensity of dislocationElemental concentrationsNano-sized precipitatesReduced-activation ferritic/martensitic steelsStrong interactionTransmission electron micrographCreep resistance
ISSN
1044-5803
Abstract
The influence of 0.015 wt% Ti addition on the formation of MX precipitates and the creep resistances of a reduced activation ferritic/martensitic (RAFM) steel has been studied. 0.1 wt% Ta was also added as same as conventional RAFM steels. Transmission electron micrographs taken from extraction replicas indicated that the area fraction of MX particles in Ta/Ti-added RAFM steel was 2.3 times higher than that in the reference steel. Atom probe tomography was employed to identify the types of MX precipitates and their interactive distribution. By using isoconcentration surfaces with different elemental concentration values, it was newly found that there are three types of MX precipitates, i.e. (Ta,V)-rich MX, Ti-rich MX and W-rich MX in the Ta/Ti-added RAFM steel. They appeared to be distributed independently in the matrix. However, in some cases, smaller sized (Ti or W)-rich MX particles were in contact with large (Ta,V)-rich MX particle. The creep rupture life of the Ta/Ti-added RAFM steel was significantly improved, as compared with the reference steel. The enhanced creep resistance can be rationalized in terms of a high density of dislocations, which were produced by a strong interaction with a higher fraction of the nano-sized MX particles within laths. © 2020 Elsevier Inc.
URI
http://hdl.handle.net/20.500.11750/12840
DOI
10.1016/j.matchar.2020.110596
Publisher
Elsevier BV
Files:
There are no files associated with this item.
Collection:
ETC1. Journal Articles


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