Dislocation density evaluation of three commercial SA508Gr.3 steels for reactor pressure vessel

Abstract

Reactor pressure vessel (RPV) plays a crucial role in the safe operation of nuclear power plants (NPPs). However, RPV steels are generally subjected to high-energy neutron irradiation during the entire in-service lifetime, which causes the hardening and embrittlement of RPV steels. The dislocation density (ρ) is known to affect strongly the mechanical properties of RPV steels. The dislocation density of three commercial SA508 Gr.3 steels manufactured by different countries was thoroughly investigated by X-ray diffraction (XRD), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The dislocation densities of three SA508 Gr.3 steels calculated by XRD are as high as 1013 m−2 and consistent with results of tempered steels reported in prior studies. The results calculated by XRD match qualitatively with those obtained from TEM and kernel average misorientation (KAM) analysis of EBSD (EBSD-KAM).