On the link of the embrittlement mechanisms and microcrack nucleation and propagation properties for RPV steels. Part I. Materials, study strategy and deformation properties

Abstract

Further development of local approach models is considered from viewpoint of links of local brittle fracture properties with embrittlement mechanisms and fracture modes for RPV steels. Experimental and numerical investigations have been performed that allows one to find how various embrittlement mechanisms and fracture modes are connected with the conditions of nucleation and propagation of microcracks resulting in brittle fracture of RPV steels. The experimental and numerical investigations have been performed for 2Cr-Ni-Mo-V steel and A533 steel used for RPVs of WWER and PWR types. RPV steels have been studied in the following states: (1) the initial (as-produced) state; (2) the thermally-embrittled state modelling hardening mechanism of radiation embrittlement; (3) the thermally-embrittled state modelling non-hardening mechanism of radiation embrittlement; (4) the irradiated state. Experimental studies include testing smooth and notched round bars and cracked compact tension specimens. Numerical studies aim to obtain microcrack nucleation and propagation properties for all the investigated states of the materials. Part I of the paper represents the test results of smooth round bars from the investigated materials in various states and the stress–strain curves determined over wide temperature range. The numerical and experimental results for various specimens are represented and compared in Part II.