Recrystallisation behaviour of a fully austenitic Nb-stabilised stainless steelCitation formats
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Recrystallisation behaviour of a fully austenitic Nb-stabilised stainless steel. / Barcellini, Chiara; Dumbill, Simon; Jimenez-Melero, Enrique.
In: Journal of Microscopy, Vol. 274, No. 1, 04.2019, p. 3-12.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Recrystallisation behaviour of a fully austenitic Nb-stabilised stainless steel
AU - Barcellini, Chiara
AU - Dumbill, Simon
AU - Jimenez-Melero, Enrique
PY - 2019/4
Y1 - 2019/4
N2 - We have performed an in-depth characterisation of the microstructure evolution of 20Cr-25Ni Nb-stabilised austenitic stainless steel during 1h isochronal annealing up to 1100°C using scanning electron microscopy. This steel grade is used as cladding material in advanced gas-cooled fission reactors, due to its resistance to thermal creep and oxidation. The initial deformed microstructure undergoes recrystallisation via a strain-induced boundary migration mechanism, attaining a fully recrystallised microstructure at 850C. A number of twins are observed in the vicinity of deformation bands prior to the start of recrystallisation. New Nb(C,N) particles form gradually in the microstructure, and the particle dispersion presents a maximum volume fraction of 2.7% at 930°C. At higher temperatures, the smaller particles become unstable and gradually dissolve in the matrix. Consequently, the Zener pinning pressure exerted on the grain boundaries is progressively released, triggering the growth of the austenite grains up to an average size of 47m at 1100°C. The observed temperature window for recrystallisation and grain growth can be predicted by a unified model based primarily on the migration of high and low angle grain boundaries.
AB - We have performed an in-depth characterisation of the microstructure evolution of 20Cr-25Ni Nb-stabilised austenitic stainless steel during 1h isochronal annealing up to 1100°C using scanning electron microscopy. This steel grade is used as cladding material in advanced gas-cooled fission reactors, due to its resistance to thermal creep and oxidation. The initial deformed microstructure undergoes recrystallisation via a strain-induced boundary migration mechanism, attaining a fully recrystallised microstructure at 850C. A number of twins are observed in the vicinity of deformation bands prior to the start of recrystallisation. New Nb(C,N) particles form gradually in the microstructure, and the particle dispersion presents a maximum volume fraction of 2.7% at 930°C. At higher temperatures, the smaller particles become unstable and gradually dissolve in the matrix. Consequently, the Zener pinning pressure exerted on the grain boundaries is progressively released, triggering the growth of the austenite grains up to an average size of 47m at 1100°C. The observed temperature window for recrystallisation and grain growth can be predicted by a unified model based primarily on the migration of high and low angle grain boundaries.
U2 - 10.1111/jmi.12776
DO - 10.1111/jmi.12776
M3 - Article
VL - 274
SP - 3
EP - 12
JO - Journal of Microscopy
JF - Journal of Microscopy
SN - 0022-2720
IS - 1
ER -