Radiation and thermal embrittlement of RPV steels: the links of embrittlement mechanisms, fracture modes and microcrack nucleation and propagation properties. Part 3: Brittle fracture modelling and analysis of the link of microcrack nucleation and propagation properties and embrittlement mechanisms

Abstract

Radiation and thermal embrittlement of RPV steels are studied from viewpoint of links of brittle fracture properties on micro- and macroscales. Brittle fracture properties on macroscale (such as fracture toughness and fracture stress) and the critical parameters controlling nucleation and propagation of microcracks are determined on the basis of the probabilistic brittle fracture model Prometey. The experimental and numerical investigations are performed for 2Cr–Ni–Mo-V steel and A533 steel used for RPVs of WWER and PWR types. RPV steels are studied in the following states: (1) the initial (as-produced) state; (2) the thermally-embrittled state modelling hardening mechanism of embrittlement; (3) the thermally-embrittled state modelling non-hardening mechanism of embrittlement; (4) the irradiated state. The test results of various specimens (smooth and notched round bars and cracked compact tension specimens) from the investigated steels in various states are represented over brittle fracture temperature range. Brittle fracture modelling is performed with the Prometey model for all the above specimens, and the experimental and numerical results are compared. On the basis of the obtained results the links between embrittlement mechanisms, fracture modes and microcrack nucleation and propagation properties are found.