Specimen reconstitution method for the assessment of fracture properties of reactor pressure vessel steels

Routine testing of the fracture properties of irradiated surveillance specimens is a critical method for evaluating irradiation embrittlement in reactor pressure vessel (RPV) steels. Given the limited space in irradiation surveillance tubes, specimen reconstitution technology is expected to provide a viable solution to the shortage of irradiated specimens. This study investigates the specimen reconstitution method for 16MND5 steel 0.5 T CT specimens used in the RPV. By studying the local mechanical properties of the residual specimen and performing finite element analysis of the crack tip plastic zone, the appropriate size for specimen reconstitution is determined. The electron beam welding method is used to join the residual specimen and the base material, and the J-integral formula for the reconstituted specimen is determined based on the finite element analysis, taking into account the influence of the weld seam and the degradation of the mechanical properties of the residual specimen. The feasibility of the specimen reconstitution method is validated through fracture tests on base material specimens and reconstituted specimens at different temperature.