Effect of the bainitic and martensitic microstructures on the hardening and embrittlement under neutron irradiation of a reactor pressure vessel steel

Bernard Marini (1) , X. Averty (2) , P. Wident (1) , P Forget (1) , F. Barcelo (1)

1 SRMA - Service des Recherches Métallurgiques Appliquées
2 SEMI - Service d'Etudes des Matériaux Irradiés

The hardening and the embrittlement under neutron irradiation of a RPV steel considering three different coarse grained microstructures (bainite, bainite-martensite and martensite) have been investigated. Bainite and martensite have a comparable irradiation induced temperature transition shifts but hardening is smaller for martensite than for bainite. Bainite appears to be less sensitive to non-hardening embrittlement (NHE) than martensite. The onset of brittle intergranular fracture after irradiation for the martensitic microstructure is likely the origin of this difference of sensitivity to NHE. However, the bainitic-martensitic microstructure has the largest irradiation induced shift and is the most sensitive to NHE amongst all the tested microstructures. These results show that the microstructure is an important parameter to control the irradiation induced non hardening embrittlement and the enhancement of the brittle intergranular fracture in reactor pressure vessel steels.

Keywords: RPV steel; Irradiation induced embrittlement; microstructure; bainite; martensite

Domains: Physics [physics]; Nuclear Theory [nucl-th]; Physics [physics]; Nuclear Experiment [nucl-ex]

Bernard Marini, X. Averty, P. Wident, P Forget, F. Barcelo. Effect of the bainitic and martensitic microstructures on the hardening and embrittlement under neutron irradiation of a reactor pressure vessel steel. Journal of Nuclear Materials, 2015, 465, pp.20-27. ⟨10.1016/j.jnucmat.2015.05.023⟩. ⟨cea-02385950⟩